Thank you for the video. I have a very stupid question. What happen if the mechanic install younone of the bumber upside down? Is there any major problem?
This is the best video about bumper stop. I just change my status and Everytime I go over a noise coming from struts and I couldn't figure out what it was . I will check where bumper stop is located tomorrow
If there's no bump stop that could certainly cause noise - or worse. Make sure you have a factory service manual if you're working on your suspension. Good luck.
It's a likely cause - bump stops will wear out or crack. I'd check them every 20-30k miles or when you start noticing harder impacts. Blown dampers could contribute as well. Good luck!
@@SuspensionTruth I have brand new Bilstein B4 shocks, new outer tie rods, new control arm, sway bar endinks and sway bar bushings and I still keep feeling the bang only to discover just yesterday that bump stops are blown. Thanks for this information.
@@SuspensionTruth Facts. And every mechanic I took my car to said everything was ok under inspection but no one checked the bump stop even when they all thought it was the strut mounts. Mounts were in great condition but I am still replacing them as they've never been replaced before.
Your video is very informative! I have a couple vehicles as I am a car collector and 2 vehicles I had to replace all shocks. Both dont have a bump stop on any of the shocks and they are both lowered with Tein springs and koni orange struts. The honda bottoms out a little and the impact is harsh. Now that I know the bump stop protects the metal to metal impact to a certain point. I will have to look into buying some.
Excellent! If you're looking for specific recommendations from me, you can send in a consultation form. Or keep searching and then experiment. The Speedthane line of bump stops we sell through 5Xracing.com and available through others sources is very high-Quality. Good luck!
Damn the guy that install my new assembled struts on my 2010 Camry didn’t swap over the old bump stops. I even asked him to. Now the car is so harsh over bumps. So annoyed
Shaikh, Thanks for the content. It's your videos and postings on the internet combined with Carroll Smith's thoughts on the subject in 'Tune to Win' that have pushed me to better understand the use of these devices. The problem is that in general, outside of their basic use as suspension limiters and use as secondary springs as measured in weight required to compress a specified amount, the effect these are having is poorly understood. Seeing how effective these can be in my own vehicle, which actually came configured from the factory to encourage mid-corner rotation, I'm a believer. I have a question in regards to bumpstop selection as it relates to spring frequency tuning to achieve the classic "flat ride" balance. After you've calculated your target linear spring rates according to your corner weights, motion ratios, etc: if you are depending on a long(ish), progressive rate bumpstop to provide a significant contribution to your rear spring rate how do you determine the stiffness (measured in lbs/in of compression) of the bumpstop and exactly how much bump travel you want before the bumpstop is engaged? Is it simply a matter of trial and error after you do the calculations and get it close? If you're running purely linear spring rates without using bumpstops as supplementary springs it seems like getting it right is fairly straight-forward. But when your wheel rate is effectively progressive rate due to the addition of bumpstops, how do you get it right?
Thanks for your comment and questions, Michael. What vehicle are you working with? I have seen a few German sedans that have a rear bump stop that creates a ramp in spring rate as the load increases (though the front also tends to increase somewhat proportionally). For bump stop lengths, I find there is always some trial and error involved. Spreadsheet calculations get me close but I always reserve the right to trim bump stops as a final step (and it's often what we do on a new application). That's also where I find it important to have photos of the car (front and side) in cornering to see how much travel you're using. To get reference points in the shop/garage, you install the damper assembly minus the spring and jack under the lower control arm (or hub) to static height. Note the bump stop clearance and the fender-to-hub-center gap (wheel is off right now). Then move to bump stop contact and repeat those measurements. Finally, go to full bump where the corner wants to lift off the jack stand or jack pad. That should be close (not exactly) to your full compression position but the loads will not be the same. You'll have a more direct measurement of how much 'free' bump travel you have, when the bump stop contact, and how far it compresses. A compact gopro style camera placed in the wheel well is also very useful for this kind of visualization. Zip ties won't work very well when you're using a longer / softer stop and lower spring rate. Mind you, the amount of Real World bump stop usage depends rather heavily on the overall ratio of rebound-to-bump damping (including the vertical 'lift' provided by the internal nitrogen pressure). I design the front suspension to almost never jack down and to have minimal rear jacking down to encourage rotation (use of the bump stop during cornering). If you don't know the damper curves and the gas pressure then you're really flying by the seat of your pants and more trial and error will be needed to get the right balance of bump stop length / density and spring rates / sway bars. More broadly, when I design a setup (such as Street class autocross, where you keep the stock springs but can change bump stops and either front or rear sway bar but not both), I am aiming for a little jacking down on the rear end of the car and no jacking down on the front end. I include the bump stop in the overall critical damping calculation by taking the approximate bump stop rate for about 1 inch of compression travel. With our 'red' stops, that's 100 lb/in, white stops is 200 lb/in, blue stops is 330 lb/in. That seems to work quite well. I do this front and rear when tuning with stock / soft springs. I hope that helps! For more info and specifics to your vehicle, you know what to do ;)
Thanks a lot for the thoughtful reply, I really appreciate it. So up front, at some point I do intend to seek a revalved set of Bilsteins to pair with Ground Control sleeves. But I have some big life changes ahead in the short term and need to be settled before I spend more money on my car. The original question comes from a place of being someone who spends entirely too much of his free time learning about how to properly set up a suspension. You very thoroughly answered my question, thank you for that. I'm not looking for any specific setup advice (I'll seek that later via your website), but I'll share what I know about my specific car. If anything, for your information. The car is a 2010 Volkswagen GTI. I haven't measured it myself (I intend to at some point in the future), but the forums tell me that the motion ratios are .98 front and .65 rear; the front is coil over strut and the rear is not, although the bumpstops are mounted on the strut. OEM anti-roll bars are 23 mm diameter tubular type with 3 mm wall front, and 21.7 mm diameter with 3 mm wall at the rear rear (overall length and length of arms between front and rear are almost the same, very close). Springs are believed to be in the 200 lb/in range; with the motion ratios being what they are, the rear springs are certainly stiffer, but I could not tell you by how much. The front bumpstops are 70 mm in length, and the rears are 133 mm in length; all are microcellular urethane with a shape that suggests a highly progressive curve (they are shaped much like similar length Eibach ERS bumpstops). I've measured distance from static ride height to bumpstop engagement, but recognize that the method I used was less precise as I was just trying to get a rough idea as I was learning about bumpstop tuning and trying to understand why my car handles the way it does. Distance from static to bumpstop, front, was about 1.5 inches, and the rear was about .25 inches; the rear measurement not being a huge surprise because of the 133 mm length stops. I did some budget maintenance in the last year to keep the car feeling fresh; I couldn't responsibly buy what I wanted, but something needed to be done. Koni Sports with new, stiffer rubber top mounts up front, and solid rubber Audi TT rear position control arm bushings with OEM length bumpstops. The Konis were set by the seat of my pants at 1 full turn from soft. Handling characteristics.... at low vehicle speeds the front tires bite better and change direction with a bit of trail braking; it'll never be a CRX but it carries the weight well with a smooth hand. In quick slalom-like transitions modulating the throttle to move load forward as you turn the steering wheel works great. Essentially understeer at turn in only happens if you turn the wheel too fast without adding the appropriate amount of load to the front tires (via throttle or brakes, depending). Understeer will also happen if your brake to steering angle inputs are too aggressive, but it's very smooth, easy to modulate, and doesn't feel like front end grip is being negatively impacted by the bumpstops (setup well for a street car); I have never felt the rear end want to come around while braking and entering. Mid corner behavior leans slightly towards oversteer. If I were to take my car to a skidpad and simulated a decreasing radius turn, but instead of allowing my vehicle's speed to decrease as the radius became tighter (adding throttle to maintain momentum as I turned the steering wheel), the rear end would come around before the front tires washed out. The car is very responsive to mid corner trailing throttle adjustments to the point that cambered, decreasing radius clover-leaf like freeway on-ramps are super fun. Unfortunately the stability control can't be turned off, but with proper throttle control it doesn't interfere. On track out with traction control turned off, XDS does a great job of getting power down. For a FWD car with an open differential and the electronic brake trickery, it's surprisingly good so long as you develop a sensitivity to that inside front wheel. The car doesn't offer a lot of feedback when you've pushed it slightly too far, but once you learn it the car. Anyway, thanks again!
It sounds like a fun package all-around. VW definitely knows how to tune a good suspension and I have a lot of respect for the level of engineering that goes into their suspension design. If you wanted to make the car more neutral in high-g mid-corner turns, you could trim the rear bump stop slightly. I'd trim from the top, keeping the progressive 'nose' of narrower end of the bump stop facing the shock body. Perhaps remove 10mm and have some 3mm packers handy. But having the rear end come around before the front is usually what an aggressive driver aims for so sounds like you've right in neutral-handling range. Enjoy!
Question... A front heavy volvo S60r, lowered 2" and took the rake out. The Springs are known to have a low spring rate for comfort. It has electronic 4c continuously variable suspension, with 14%, 20% or 40% dampening baselines. Car seems to take a 90° corner @ 50mph better with 14% dampening, loose...seems odd. It puts a good feeling of articulation to the rear and lots of body movement; which turns in much better.. An autocross would be better like this. Higher speed 100mph sweepers, 40% stiff, is more confident. But seems to push the front end a lot more with more abrupt maneuvers at lower speeds. More stable at high speeds I guess. the car feels more like it doesnt want to turn the body as quick. Bumps in the road at 40% jolt through the cars front end with obvious loss in grip. Like no spring help.. overdampened, which I guess is expected it's for track use. It also tends to crash over large road seam heaves. ---^---. Increasingly harsh with dampening. At 14% it can still then bottom out hard with a similar crash if the road surface changes too much. I just can't figure out why. I still cant completely tell if its crashing on impact or falling down and crashing on the other side due to jack down. Seems like the initial hit, but the shocks are only 14%. Also feels like the corner weight is being transferred more through the strut rod into the chassis than the springs. At these points the strut rate is higher than the spring rate! Hitting a bump with higher shock dampening than the spring rate it not going to feel nice. So when cornering hard it may jack up the shock to 80% to reduce body roll, but hitting a bump becomes an issue. Lol. I'm trying to balance it so it works well at all three settings with better range of road surfaces. It seems to me the front spring rate is too low, I'm thinking with help from a much longer progressive bump. Sitting on the bump stop, or near it at all times. I have ~ 36mm right now and looking going to a 76mm and then trimming if needed to get near full static length... will there be and ride benifit to leaving a small gap or should I go full helper spring and use it the whole way I wonder. I know its vehicle specific. I'm thinking I can reduce the front end jack down with longer bump stops. While also softening the bottoming out from jolting through the chassis when the shock is variably stiffer. I was working on a Lexus is330 that had huge full length progressive bump stops; obvious helper springs at this point. Lexus's obviously ride very soft and supple... so I'm actually looking at buying those and trimming the length to fit my struts, and Riding on them at all times to act as a helper spring. I'm interested to try it as it would make a huge change in the car, could be really good or bad. We haven't even got into the back yet, it seems to bounce the rear on certain deep car length dips like a small creek bridge. . ------\_____/------ Its hitting the bump stops and then out the other side it launches up.. lol I have a pretty long bump stop on the rear, same as stock set up for 3" higher car.. Doesn't seem to contact much and was thinking keep it longer to tighten on turn in. Keep in mind, the car is only about 3-4" off the ground under the center at the exhaust. Right now I have never bottomed out or scraped bumpers or tail pipes. I think partially because the taller bump stops on the rear are limiting dip travel. ? Any of this 12 paragraphs make sense, approve or dismiss any theory or understanding? Backwards anywhere? Lol Well it started simple, but soon realized it was complex. Lol
Recently had my suspension done on the right front wheel & new shock absorber was fitted. My car has Eibach lowering springs then immediately started hearing a hard knock sound on every speed bump & informed the repairer. They advised they'll fit a bump stop now have another issue, car is stiff no up/down movement when checking shock compression and ride height has also now increased. Can you please advise how to address my issue
Another reason to dislike / distrust lowering springs. If there was no bump stop then the damper likely was damaged. Find a more competent shop. I personally would stick with stock suspension unless you make a complete, effective change to springs / damper/ bump stops. Lowering springs are almost universally a bad idea. They sound good and easy, but can often cause problems. The lack of a bump stop is definitely going to cause damage on a stock type suspension. Good luck.
Thanks for the video! My 2007 Civic has just done 42,000 Kilometers till date and went for the annual service last month. After the service was over and when I drove the vehicle, I was subjected to an awfully bumpy ride which was never there earlier. The portion of the car behind the front wheels just bottoms out when traversing speed bumps. The mechanic just said the shocks have failed and they need to replace the strut assembly as a whole! Is there any foul play behind this? Is there a possibility that they have removed the bump stops in the suspension?
The timing is strange, indeed. However you have 15 year old dampers (if original). Canadian car? Very cold Temperatures can affect seal integrity. I suggest you have another, better-reviewed shop examine the suspension and the work performed. Factory shocks / struts can last a surprisingly long time as long as there is a bump stock present and the damper is of good quality.
Do you sell replacement bump stops for KW V3? Wanted to replace the foam like material that KW uses in their suspension. Let me know if you need the KW part number. Thanks!
If you're willing to pay a consult fee, I can advise you on alternative bump stops. Otherwise I suggest you look on Summit Racing or 5X Racing for something that looks similar. The KW part number doesn't help me because I don't use those parts. For any further questions send an inquiry through the fatcatmotorsports.com Contact page.
Thank you for imparting this bump stop knowledge. A question on your stops. A Koni Yellow suspension kit includes 54mm stops where your advice for the car recommends 36F/46R. Can the stops be cut shorter? If so, what end to cut?
54mm is a softer 'Comfort' bump stop generally intended for stock height. 36/46 is more for lowered / 'Sporty' applications. The 36mm is shorter but firmer than a 54mm. IMO, leave them alone as either will work better than factory Mazda stops.
I appreciate your input and will run with it. We are in the initial phase of upgrading this 30 year old and about to install the shock/spring kit. I didn't mention the goal is street use with autocross fun days and a rare track day thrown in. Thanks.
Most aftermarket bump stops will float over the shock shaft. I haven't found this to be a problem. Depending on the damper, dust boots / gaiters may be recommended or required. You need to check with the damper manufacturer to find out. Some Bilstein models have a 'wiper seal' that keeps dirt from going into the shock body and boots aren't required. Depending on where you drive and road conditions a boot may be a good idea.
Thank you very much Mr. Shaikh So I have lexuz GX460 2022 and the car has some sort of unpleasent ride on the bumby roads, friend of mine decided to cut/shorten the rear bumb stop and major imporvement was noticed for the ride and car whole body stability on the bumbs, so my question is it ok to shorten the factory bumbs stop (assuming it is too long, will it cause uncomfortable ride?), what about getting the dobninsons hydrolic bumb stop as a replacement will it improve the ride? I really need tour advise, apprciated
Thanks for the video! You said you don't want to have the car riding on the bump stop! Why not? I recently replaced my ford transit bump stop with a pair of Sumo springs, which is now riding on the bump stop. No clearance as with the factory bump stop! was that a good idea, or bad? Thanks!
You're welcome, John. Your vehicle is a cargo van, designed to take very high loads, right (you might use it different)? I've worked on Daimler Sprinter Vans so I have some familiarity with those platforms in general. An advantage of having a bump stop is you get more support when loading up that corner (usually in a cornering situation). For a heavier vehicle sometimes you need more load carrying capacity and if the standard bump stop was a harder material, or softer, then you are making the load come in more gradually. However, a disadvantage is you reduce the ability to absorb larger bumps. There's always a trade-off, so it isn't universally good or bad, but depends on your goals. fatcatmotorsports.com/igallery/graphics/CHART_FCM_vs_ES_2.jpg Look for graphs of 'bump stop load vs. displacement', or force vs. distance. Modern bump stops (if the Sumo springs are micro-cellular polyurethane {MCU} ) have a region that gives a softer force increase and then the force builds faster (progressive / exponential). You can make a vehicle ride decently-well when using bump stops (again, larger bumps may be harsher) so it's better if they're longer and softer density vs. shorter and higher density. The former provides a wider region of that softer force build up.
I don't know anything about that setup to give you a specific answer. If the Belltech are tuned like most aftermarket dampers they will always want to bottom out (more rebound than compression) so it won't matter how many bump stops you have but too little bump stop protection could cause damage to the suspension. I would ask the vendor for their recommendation. Good luck.
I have a 96 chevy Silverado c1500 and was wonder why when I hit a hard bump or dip in the road I hear a thud like it's bottoming out. Brand new shocks summit racing 2 inch lowering so the truck sits level in the rear to match the front which looks amazing. I have been wondering if changing the bump stops would prevent the thud that I hear when going over big bumps or dips in the road?? Any help would be greatly appreciated. Thanks in advance. Joe
It sounds like you know what's going on intuitively - you're likely bottoming out. Lowering without sufficiently increasing spring rate, and considering Flat Ride, and properly addressing HOW the SHOCKS behave will almost always lead to problems. As I just replied to someone on the E90 Bilstein video where I showed how to access the internal bump stop, bump stops matter but the dampers also matter and total suspension travel really matters. I helped a customer who had a Miata for fun which we upgraded then later work on his Ford SuperCrew for work duty and family trips. He wanted it lowered and able to handle sufficient load but also have a decent ride for long trips. It took a while to get things dialed on springs, how many leafs, heights, etc. but in the end he's happy. A key ingredient was making the dampers work right as he tried off-the-shelf Bilsteins and they just weren't very smooth. I don't know what 'brand new shocks' means or how what you have works. Unless you ask the right questions from the shock vendor you won't get getting a trophy truck / baja-style upgrade. What I mean is, you'll have looks but not a better ride or help avoiding bottoming. The best help I can offer is to find out on forums if someone has gone your direction and had success. My services are high-end so this is the only free advice I can give you. If you want to engage more you can send in a consultation form and make a 30 min payment here: www.fatcatmotorsports.com/fcm_elite_consult_form.htm
A high quality MCU bump stop would reduce the severity of bottoming out. You'd also want to make sure your damper (if adjustable) isn't biased too much on rebound (which causes even MORE bump stop contact and increases the frequency of bottoming out). The damper is really a crucial factor in how often and how severely you run out of suspension travel, although you need to not be running too low a height for what the springs can support. The bump stop can help, but I wouldn't overly rely on it if the damper is strongly rebound-biased or the springs aren't stiff enough to reduce suspension deflection.
I had my bump stops cut 25mm from the bottom and reused the upper portion after installing tein lowering springs. I didn't like the ride quality and returned back to stock, is it ok that my bump stops were not replaced back to original and currently using shorter length than before? Thank you.
In terms of function, cutting from the bottom is usually the wrong place to trim since the 'progressive nose' is removed and you get more of an 'on/off switch' behavior from the bump stop. I generally hate lowering springs as well, since they are invariably too soft for the amount of lowering (too much). Being at a higher ride height makes a lot of difference, eh? If you are okay with the way the car rides with the cut bump stops, then I'd say you're fine. My own thought is making sure you have enough protection with the cut bump stop but if they were stock bump stops originally then I imagine you still have 30-40 mm of bump stop remaining.
Exactly feels too soft especially at high speeds and bumps, I end up bottoming out compared to when i was riding stock. Are lowering springs softer than stock springs? Does it mean that lowering springs are just comfortable at low speeds and less bumpy roads? Will coilovers solve the problem of bottoming out since its spring rates are stiffer and i will end up bouncing instead on such bumps instead of bottoming out?
Lowering springs emphasize looks over function. They are typically 20 to 30% stiffer than stock springs but the amount of lowering they give (usually over an inch) is too much for that small a spring rate change. So you are into the bump stops more often than with factory springs, if not already riding on them at static ride height. In my experience and understanding, having an appropriate spring rate (often double the stock rate or more) and height adjustability via a coilover will give you sufficient spring rate to avoid constant bottoming out. However, if the coilover setup doesn't have Flat Ride or if the damping isn't tunes correctly then the coil overs are not going to work and the ride will be more uncomfortable than before. It's all about having the elements work together which is why I talk about Ride Harmony and Race Synergy. If you wanted further assistance you can contact us through the website and schedule a consultation to discuss options.
I have a question should you bump stop be remain firmly at the top?. My bump.stops slide up and down my strut freely but not sure if it is correct or not?
I haven't found a floating bump stop to be an issue, however it's a good idea to use a dust cover / dust boot /gaiter so you aren't introducing more dirt and debris between the bump stop and the shaft or seals that could cause wear.
Do i need to slice the bump stop thinner after installing coilover? Because i feel like the rear is quite bumpy, despite adjusting the dampening and also using a 5k spring at the back
I'd ask the people who made your setup why it's so bumpy... If the damping isn't right then cutting the bump stop may only reduce some of the bumpiness. It could also damage your dampers. Impossible to say without knowing a lot more about the setup (consult form) and having a consult payment. Without a damping change, any setup I've seen will either jack down (too much rebound) or launch (too much compression) with the former more likely. The bump stops are part of the situation, but not a 'cure-all.'
There is this simulator called assetto corsa competizione. Official Blancpain GT3 sim , and actual GT3 drivers say its pretty realistic as well like David Perel. In the sim in the aggressive setup preset almost every car has very little bumpstop height on front but like 20-30 times bumpstop height at the rear. Why are they running it too little on front and too much on the rear
Interesting. I can think of a few reasons. How about you watch the "Tuning with Packers" video and then reply back with your own ideas as to why the GT3 may work that way? th-cam.com/video/HV6fgwCjZ2E/w-d-xo.html And part 2 th-cam.com/video/uikpAQB6IYA/w-d-xo.html
Suspension Truth by Fat Cat Motorsports, Inc. Thanks a lot for replying. I watched your videos and im amazed by your knowledge , your channel deserves way more subs. I also scrolled throught ACC forums to see if they had any discussions about this same thing and found out that somebody already asked it and one of the devs replied to him and linked a video he made about this. th-cam.com/video/iQ1guCnrv5Y/w-d-xo.html So basically reason why they run so little bumpstop range in irl gt3 cars is because of their aero pitch sensitivity. When braking center of pressure moves heavily to the front and can throw the car off if you are not really careful while trailbraking. And reason why they run so high bumpstop range at the rear is because of they want traction over kerbs and bumps on the corner exit. Lot of the tracks in blancpain gt3 calendar have lot of bumps and kerbs especially zolder. And i want to thank you again for making those videos , i learned lot of stuff just by watching those 2 videos that you have made.
You answered your own question, kudos! Bump stops are a very important part of tuning on many cars; they can be used very intelligently, while some vendors choose to ignore (or omit) them. The flexibility of the setup suffers when all the available tools aren't utilized. I also know that some vehicles (including some Porsches) have used internal 'rebound stops' - that's another interesting feature which I'd be curious of the ACC software allows for! Things get trickier with setup then... VERY ride height dependent and harder to tune vs. bump stop length (or range as you say).
Suspension Truth by Fat Cat Motorsports, Inc. internal rebound stops on the porsche are on their road cars right? Im not sure but maybe gt3 regulations dont allow them. But i ll ask the devs if the porsche 911 gt3r has them too and whether or not that exact thing is implemented in the sim
I'd be surprised if regs would restrict internals beyond preventing active suspension (which I presume aren't allowed, like F1). But, tuning is tricky as I said. A late 2000's Cayman S I improved had internal rebound / droop springs on the OE struts.
Do you have a Bilstein part number for front strut bumpstops? Or a source? All bump stops I can find are too large a diameter to fit within the bilstein strut.
You will need to call them to clarify p/n and order. From my part notes I see a 'soft'-density bumpstop as E4-AP2-Z045A09 and a 'medium'-density as E4-AP2-Z050A00. I've used both inside strut housings. Good luck.
hello can I ask? can a worn bump stop cause tire rubbing? hope u can answer my question because my tire is rubbing when it hits a bump or an uneven road with or without a passenger🙏
I have eibach coils so it raises my vehicle like an inch and now my front struts bottom out on speed bumps. Would those packers help out and if so how thick would they have to be?I have one inch ones but havnt put them on yet.Would this solve my issue?
I've never heard of eibach springs 'raising' a car - sounds more like it lowered it, and you're bottoming now. I'd contact a professional mechanic in your area and get their advice. If you don't use a proper coil-over system, you're going to run into problems like this. 'What lowering springs should I get' is a video I made - watch it.
Good on bigger and hard on smaller sounds like too much gas pressure in the damper. New dampers often need some time to break in, especially if they are monotubes. But if you're concerned have a qualified mechanic check things out.
@@SuspensionTruth ok thanks for big help.no im not a mechanic but im trying to understand things by your videos maybe one day ill be able to fix my car by myself.thanks a lot
Foam and rubber are different things. BOTH rubber and micro-cellular ("foam") MCU bump stops will degrade with dirt and abrasion. The higher quality MCU lasts longer. Rubber lasts longer still but is very hard and is a poor bump stop material, hence why rarely used now.
So most cars should have bump stops on all struts and shock if you’re able to put them on? (Lots of shocks have the eyelet on top and bottom I guess like a sealed unit - sorry I’m a newbie-intermediate)
Yes, some kind of bump stops adds protection as well as tunabilty to the suspension. For an eyelet damper you'd need to carefully heat the bushing housing near the shock shaft to warm up and loosen threadlocker. Then clamp the shaft with soft jaws (ideally in a shop press) and use a long 3/8" or similar extension through the eyelet center to rotate the eyelet housIng free. From there you can service the damper and also change / replace a bump stop. I'm not sure I've done a video on this...
Hello. I planing install a sport suspension(lowering shocks and lowering springs). And thinking what to do with bump stops..🙄 need a cut or not ?? They are standart.
2 year old video. But It was cycled..... The bump stop helps to not blow the shocks .limiting the mechanical failure. Nothing to do with passenger ride really at all. It's about helping the shock survive the forces ,exceeding is intended design. Good video...."butt!"
Close but not completly. If the bump was about not bottoming out then they would just put a stiffer spring on the car. Bump has a lot more to do with the caster camber gain and the maximum grip curve. Not destroying the suspension is a byproduct of that.
Both comments have elements of truth. Bump stops are used to protect the suspension components at full compression, also keep the chassis from bottoming on the ground (also chassis bump stops come into play here for some cars), also to modify the handling behavior (usually toward more front roll stiffness = more understeer), and also to manage having more passengers or more cargo.
Never seen it be a problem to be loose in terms of function. However, some OE bump stop are designed to have a dust boot attached bump stop ID is sized to stay on the shaft near the top of the travel so the dust boot covers the shaft.
I have CRV 2002, and when it is on bump r dump feel like a trailer which have no shock absorber r Sturt. Even a smal stone under the tyre shake my car. So what is the reason? Sorry for language
I really can't say without more information. It's 18 years old, so the struts / shocks could be worn, the bump stops could be worn / degraded, suspension bushings worn / degraded. Many possibilities. I suggest you take your CRV to a local mechanic and have them inspect it. Good luck.
@@SuspensionTruth Thanks for giving me your time, I did that and the Sturt and dump stopper was bad, so I changed the Sturt. Now I feel good. The car is also smooth now.
It could. More likely you'll hear banging sounds if the suspension bottoms out. Squeaking could be from bushings that are worn out or not lubricated. Get help from a mechanic if you're unsure how to diagnose.
The suspension needs room to work properly, to give good comfort AND to give predictable handling. Lowering any vehicle without careful choice of spring rate, damping, bump stops and other variables will make the car LESS COMFORTABLE. Changing out bump stops MIGHT help but will not fix other problems caused by lowering.
Assuming you have a strut up front (~19-22mm OD shaft) and shock rear (12-14mm OD shaft), you can get a pair of 47mm Speedthane strut-style bump stops FOR THE FRONT and 58mm 'red' shock bump stop FOR THE REAR from a variety of places, including 5Xracing.com (my distributor for FCM bump stop kits). The Mini Cooper R56 kit would likely work for your '04 RSX but measure/check the the dampers you have to be sure.
@Satya Chandu, if the bump stop is ENGAGED at static ride height, then it WILL increase the ride height. Otherwise, if there's no bump stop contact at static height then there's no height change.
Someone just replied to this comment but I accidentally removed instead of approved it (YT holds certains comments and I don't dont have manually set to approve). Please repost if you see this.
Thank you for the video.
I have a very stupid question.
What happen if the mechanic install younone of the bumber upside down?
Is there any major problem?
There should be no problem, as long as the surface above and below the bump stop is wide enough to support the load.
@@SuspensionTruth Mine left the bump stock out entirely. Nearly damaged my brand new shock. I never found out until almost 6 months!!
That's pretty disappointing... hope you got at least a sincere apology.
This is the best video about bumper stop. I just change my status and Everytime I go over a noise coming from struts and I couldn't figure out what it was . I will check where bumper stop is located tomorrow
If there's no bump stop that could certainly cause noise - or worse. Make sure you have a factory service manual if you're working on your suspension. Good luck.
Thank you so much for this information. This is the reason I am getting mad impact and noise over bumps. Gonna replace mine.
It's a likely cause - bump stops will wear out or crack. I'd check them every 20-30k miles or when you start noticing harder impacts. Blown dampers could contribute as well. Good luck!
@@SuspensionTruth I have brand new Bilstein B4 shocks, new outer tie rods, new control arm, sway bar endinks and sway bar bushings and I still keep feeling the bang only to discover just yesterday that bump stops are blown. Thanks for this information.
Glad to help. I heard long ago that what we don't know we don't know is likely to catch us off guard.
@@SuspensionTruth Facts. And every mechanic I took my car to said everything was ok under inspection but no one checked the bump stop even when they all thought it was the strut mounts. Mounts were in great condition but I am still replacing them as they've never been replaced before.
Your video is very informative! I have a couple vehicles as I am a car collector and 2 vehicles I had to replace all shocks. Both dont have a bump stop on any of the shocks and they are both lowered with Tein springs and koni orange struts. The honda bottoms out a little and the impact is harsh. Now that I know the bump stop protects the metal to metal impact to a certain point. I will have to look into buying some.
Excellent! If you're looking for specific recommendations from me, you can send in a consultation form. Or keep searching and then experiment. The Speedthane line of bump stops we sell through 5Xracing.com and available through others sources is very high-Quality. Good luck!
Thanks dude that clunking noise was driving me crazy..it took me 2 weeks to find that noise..
Good thing you found it! If the dampers are still okay and all you needed were bump stops then consider yourself lucky.
Thank you friend.
Very unusual scenario 😂 but also clear. Good job man!
Hahah yeah I tend to get extreme but it gets a few ideas across!
Damn the guy that install my new assembled struts on my 2010 Camry didn’t swap over the old bump stops. I even asked him to. Now the car is so harsh over bumps. So annoyed
Sounds like he needs to fix that situation.
Shaikh,
Thanks for the content. It's your videos and postings on the internet combined with Carroll Smith's thoughts on the subject in 'Tune to Win' that have pushed me to better understand the use of these devices. The problem is that in general, outside of their basic use as suspension limiters and use as secondary springs as measured in weight required to compress a specified amount, the effect these are having is poorly understood. Seeing how effective these can be in my own vehicle, which actually came configured from the factory to encourage mid-corner rotation, I'm a believer.
I have a question in regards to bumpstop selection as it relates to spring frequency tuning to achieve the classic "flat ride" balance. After you've calculated your target linear spring rates according to your corner weights, motion ratios, etc: if you are depending on a long(ish), progressive rate bumpstop to provide a significant contribution to your rear spring rate how do you determine the stiffness (measured in lbs/in of compression) of the bumpstop and exactly how much bump travel you want before the bumpstop is engaged?
Is it simply a matter of trial and error after you do the calculations and get it close? If you're running purely linear spring rates without using bumpstops as supplementary springs it seems like getting it right is fairly straight-forward. But when your wheel rate is effectively progressive rate due to the addition of bumpstops, how do you get it right?
Thanks for your comment and questions, Michael. What vehicle are you working with? I have seen a few German sedans that have a rear bump stop that creates a ramp in spring rate as the load increases (though the front also tends to increase somewhat proportionally).
For bump stop lengths, I find there is always some trial and error involved. Spreadsheet calculations get me close but I always reserve the right to trim bump stops as a final step (and it's often what we do on a new application). That's also where I find it important to have photos of the car (front and side) in cornering to see how much travel you're using. To get reference points in the shop/garage, you install the damper assembly minus the spring and jack under the lower control arm (or hub) to static height. Note the bump stop clearance and the fender-to-hub-center gap (wheel is off right now). Then move to bump stop contact and repeat those measurements. Finally, go to full bump where the corner wants to lift off the jack stand or jack pad. That should be close (not exactly) to your full compression position but the loads will not be the same. You'll have a more direct measurement of how much 'free' bump travel you have, when the bump stop contact, and how far it compresses. A compact gopro style camera placed in the wheel well is also very useful for this kind of visualization. Zip ties won't work very well when you're using a longer / softer stop and lower spring rate.
Mind you, the amount of Real World bump stop usage depends rather heavily on the overall ratio of rebound-to-bump damping (including the vertical 'lift' provided by the internal nitrogen pressure). I design the front suspension to almost never jack down and to have minimal rear jacking down to encourage rotation (use of the bump stop during cornering). If you don't know the damper curves and the gas pressure then you're really flying by the seat of your pants and more trial and error will be needed to get the right balance of bump stop length / density and spring rates / sway bars.
More broadly, when I design a setup (such as Street class autocross, where you keep the stock springs but can change bump stops and either front or rear sway bar but not both), I am aiming for a little jacking down on the rear end of the car and no jacking down on the front end. I include the bump stop in the overall critical damping calculation by taking the approximate bump stop rate for about 1 inch of compression travel. With our 'red' stops, that's 100 lb/in, white stops is 200 lb/in, blue stops is 330 lb/in. That seems to work quite well. I do this front and rear when tuning with stock / soft springs.
I hope that helps! For more info and specifics to your vehicle, you know what to do ;)
Thanks a lot for the thoughtful reply, I really appreciate it. So up front, at some point I do intend to seek a revalved set of Bilsteins to pair with Ground Control sleeves. But I have some big life changes ahead in the short term and need to be settled before I spend more money on my car. The original question comes from a place of being someone who spends entirely too much of his free time learning about how to properly set up a suspension.
You very thoroughly answered my question, thank you for that. I'm not looking for any specific setup advice (I'll seek that later via your website), but I'll share what I know about my specific car. If anything, for your information.
The car is a 2010 Volkswagen GTI. I haven't measured it myself (I intend to at some point in the future), but the forums tell me that the motion ratios are .98 front and .65 rear; the front is coil over strut and the rear is not, although the bumpstops are mounted on the strut. OEM anti-roll bars are 23 mm diameter tubular type with 3 mm wall front, and 21.7 mm diameter with 3 mm wall at the rear rear (overall length and length of arms between front and rear are almost the same, very close). Springs are believed to be in the 200 lb/in range; with the motion ratios being what they are, the rear springs are certainly stiffer, but I could not tell you by how much. The front bumpstops are 70 mm in length, and the rears are 133 mm in length; all are microcellular urethane with a shape that suggests a highly progressive curve (they are shaped much like similar length Eibach ERS bumpstops).
I've measured distance from static ride height to bumpstop engagement, but recognize that the method I used was less precise as I was just trying to get a rough idea as I was learning about bumpstop tuning and trying to understand why my car handles the way it does. Distance from static to bumpstop, front, was about 1.5 inches, and the rear was about .25 inches; the rear measurement not being a huge surprise because of the 133 mm length stops.
I did some budget maintenance in the last year to keep the car feeling fresh; I couldn't responsibly buy what I wanted, but something needed to be done. Koni Sports with new, stiffer rubber top mounts up front, and solid rubber Audi TT rear position control arm bushings with OEM length bumpstops. The Konis were set by the seat of my pants at 1 full turn from soft.
Handling characteristics.... at low vehicle speeds the front tires bite better and change direction with a bit of trail braking; it'll never be a CRX but it carries the weight well with a smooth hand. In quick slalom-like transitions modulating the throttle to move load forward as you turn the steering wheel works great. Essentially understeer at turn in only happens if you turn the wheel too fast without adding the appropriate amount of load to the front tires (via throttle or brakes, depending). Understeer will also happen if your brake to steering angle inputs are too aggressive, but it's very smooth, easy to modulate, and doesn't feel like front end grip is being negatively impacted by the bumpstops (setup well for a street car); I have never felt the rear end want to come around while braking and entering.
Mid corner behavior leans slightly towards oversteer. If I were to take my car to a skidpad and simulated a decreasing radius turn, but instead of allowing my vehicle's speed to decrease as the radius became tighter (adding throttle to maintain momentum as I turned the steering wheel), the rear end would come around before the front tires washed out. The car is very responsive to mid corner trailing throttle adjustments to the point that cambered, decreasing radius clover-leaf like freeway on-ramps are super fun. Unfortunately the stability control can't be turned off, but with proper throttle control it doesn't interfere.
On track out with traction control turned off, XDS does a great job of getting power down. For a FWD car with an open differential and the electronic brake trickery, it's surprisingly good so long as you develop a sensitivity to that inside front wheel. The car doesn't offer a lot of feedback when you've pushed it slightly too far, but once you learn it the car.
Anyway, thanks again!
It sounds like a fun package all-around. VW definitely knows how to tune a good suspension and I have a lot of respect for the level of engineering that goes into their suspension design. If you wanted to make the car more neutral in high-g mid-corner turns, you could trim the rear bump stop slightly. I'd trim from the top, keeping the progressive 'nose' of narrower end of the bump stop facing the shock body. Perhaps remove 10mm and have some 3mm packers handy. But having the rear end come around before the front is usually what an aggressive driver aims for so sounds like you've right in neutral-handling range. Enjoy!
Interesting analogy, butt stop. Funny how we figure out how to explain things when we are doing something else
Very clear and concise!!
Thank you!
Very informative! Thank you!
Glad you found it helpful!
Good video. Easy to understand. Thnx 👍🏽
Thanks for the comment, glad it helped.
Question...
A front heavy volvo S60r, lowered 2" and took the rake out. The Springs are known to have a low spring rate for comfort. It has electronic 4c continuously variable suspension, with 14%, 20% or 40% dampening baselines. Car seems to take a 90° corner @ 50mph better with 14% dampening, loose...seems odd. It puts a good feeling of articulation to the rear and lots of body movement; which turns in much better.. An autocross would be better like this.
Higher speed 100mph sweepers, 40% stiff, is more confident. But seems to push the front end a lot more with more abrupt maneuvers at lower speeds. More stable at high speeds I guess. the car feels more like it doesnt want to turn the body as quick. Bumps in the road at 40% jolt through the cars front end with obvious loss in grip. Like no spring help.. overdampened, which I guess is expected it's for track use.
It also tends to crash over large road seam heaves. ---^---. Increasingly harsh with dampening. At 14% it can still then bottom out hard with a similar crash if the road surface changes too much. I just can't figure out why.
I still cant completely tell if its crashing on impact or falling down and crashing on the other side due to jack down. Seems like the initial hit, but the shocks are only 14%.
Also feels like the corner weight is being transferred more through the strut rod into the chassis than the springs. At these points the strut rate is higher than the spring rate! Hitting a bump with higher shock dampening than the spring rate it not going to feel nice. So when cornering hard it may jack up the shock to 80% to reduce body roll, but hitting a bump becomes an issue. Lol. I'm trying to balance it so it works well at all three settings with better range of road surfaces.
It seems to me the front spring rate is too low, I'm thinking with help from a much longer progressive bump. Sitting on the bump stop, or near it at all times. I have ~ 36mm right now and looking going to a 76mm and then trimming if needed to get near full static length... will there be and ride benifit to leaving a small gap or should I go full helper spring and use it the whole way I wonder. I know its vehicle specific.
I'm thinking I can reduce the front end jack down with longer bump stops. While also softening the bottoming out from jolting through the chassis when the shock is variably stiffer.
I was working on a Lexus is330 that had huge full length progressive bump stops; obvious helper springs at this point. Lexus's obviously ride very soft and supple... so I'm actually looking at buying those and trimming the length to fit my struts, and Riding on them at all times to act as a helper spring.
I'm interested to try it as it would make a huge change in the car, could be really good or bad.
We haven't even got into the back yet, it seems to bounce the rear on certain deep car length dips like a small creek bridge. . ------\_____/------ Its hitting the bump stops and then out the other side it launches up.. lol I have a pretty long bump stop on the rear, same as stock set up for 3" higher car.. Doesn't seem to contact much and was thinking keep it longer to tighten on turn in.
Keep in mind, the car is only about 3-4" off the ground under the center at the exhaust. Right now I have never bottomed out or scraped bumpers or tail pipes. I think partially because the taller bump stops on the rear are limiting dip travel. ?
Any of this 12 paragraphs make sense, approve or dismiss any theory or understanding? Backwards anywhere? Lol
Well it started simple, but soon realized it was complex. Lol
Recently had my suspension done on the right front wheel & new shock absorber was fitted. My car has Eibach lowering springs then immediately started hearing a hard knock sound on every speed bump & informed the repairer. They advised they'll fit a bump stop now have another issue, car is stiff no up/down movement when checking shock compression and ride height has also now increased.
Can you please advise how to address my issue
Another reason to dislike / distrust lowering springs. If there was no bump stop then the damper likely was damaged. Find a more competent shop. I personally would stick with stock suspension unless you make a complete, effective change to springs / damper/ bump stops. Lowering springs are almost universally a bad idea. They sound good and easy, but can often cause problems. The lack of a bump stop is definitely going to cause damage on a stock type suspension. Good luck.
Thanks for the video! My 2007 Civic has just done 42,000 Kilometers till date and went for the annual service last month. After the service was over and when I drove the vehicle, I was subjected to an awfully bumpy ride which was never there earlier. The portion of the car behind the front wheels just bottoms out when traversing speed bumps. The mechanic just said the shocks have failed and they need to replace the strut assembly as a whole! Is there any foul play behind this? Is there a possibility that they have removed the bump stops in the suspension?
The timing is strange, indeed. However you have 15 year old dampers (if original). Canadian car? Very cold Temperatures can affect seal integrity. I suggest you have another, better-reviewed shop examine the suspension and the work performed. Factory shocks / struts can last a surprisingly long time as long as there is a bump stock present and the damper is of good quality.
@@SuspensionTruth Thanks! It's an Indian car (Honda Civic FD1) driven/parked at ambient temperatures ranging from 30°C to 38°C.
Learned a lot, thanks.
Awesome video thank you for the explination.
Do you sell replacement bump stops for KW V3? Wanted to replace the foam like material that KW uses in their suspension. Let me know if you need the KW part number. Thanks!
If you're willing to pay a consult fee, I can advise you on alternative bump stops. Otherwise I suggest you look on Summit Racing or 5X Racing for something that looks similar. The KW part number doesn't help me because I don't use those parts. For any further questions send an inquiry through the fatcatmotorsports.com Contact page.
Good to know Thanks
Thank you for imparting this bump stop knowledge. A question on your stops. A Koni Yellow suspension kit includes 54mm stops where your advice for the car recommends 36F/46R. Can the stops be cut shorter? If so, what end to cut?
54mm is a softer 'Comfort' bump stop generally intended for stock height. 36/46 is more for lowered / 'Sporty' applications. The 36mm is shorter but firmer than a 54mm. IMO, leave them alone as either will work better than factory Mazda stops.
I appreciate your input and will run with it. We are in the initial phase of upgrading this 30 year old and about to install the shock/spring kit. I didn't mention the goal is street use with autocross fun days and a rare track day thrown in. Thanks.
Is the bump stop supposed to be stable or it could be moving up and down.
And also can you fix bump stop without rubber boots?
Most aftermarket bump stops will float over the shock shaft. I haven't found this to be a problem.
Depending on the damper, dust boots / gaiters may be recommended or required. You need to check with the damper manufacturer to find out. Some Bilstein models have a 'wiper seal' that keeps dirt from going into the shock body and boots aren't required. Depending on where you drive and road conditions a boot may be a good idea.
Thank you very much Mr. Shaikh
So I have lexuz GX460 2022 and the car has some sort of unpleasent ride on the bumby roads, friend of mine decided to cut/shorten the rear bumb stop and major imporvement was noticed for the ride and car whole body stability on the bumbs, so my question is it ok to shorten the factory bumbs stop (assuming it is too long, will it cause uncomfortable ride?), what about getting the dobninsons hydrolic bumb stop as a replacement will it improve the ride?
I really need tour advise, apprciated
I can provide direct advice via paid consultation: fatcatmotorsports.com/fcm_elite_consult_form.htm
Thanks for the video! You said you don't want to have the car riding on the bump stop! Why not? I recently replaced my ford transit bump stop with a pair of Sumo springs, which is now riding on the bump stop. No clearance as with the factory bump stop! was that a good idea, or bad? Thanks!
You're welcome, John. Your vehicle is a cargo van, designed to take very high loads, right (you might use it different)? I've worked on Daimler Sprinter Vans so I have some familiarity with those platforms in general. An advantage of having a bump stop is you get more support when loading up that corner (usually in a cornering situation). For a heavier vehicle sometimes you need more load carrying capacity and if the standard bump stop was a harder material, or softer, then you are making the load come in more gradually. However, a disadvantage is you reduce the ability to absorb larger bumps. There's always a trade-off, so it isn't universally good or bad, but depends on your goals.
fatcatmotorsports.com/igallery/graphics/CHART_FCM_vs_ES_2.jpg
Look for graphs of 'bump stop load vs. displacement', or force vs. distance. Modern bump stops (if the Sumo springs are micro-cellular polyurethane {MCU} ) have a region that gives a softer force increase and then the force builds faster (progressive / exponential). You can make a vehicle ride decently-well when using bump stops (again, larger bumps may be harsher) so it's better if they're longer and softer density vs. shorter and higher density. The former provides a wider region of that softer force build up.
how are yall @FCM?
Life is always interesting, yes? I trust all is well for you.
@@SuspensionTruth all is well. and indeed
Hello I have my belltech front struts set at 0 with only 1 of 2 black bump stops on the shaft. They bottom out should I have put both of them on. Thnx
I don't know anything about that setup to give you a specific answer. If the Belltech are tuned like most aftermarket dampers they will always want to bottom out (more rebound than compression) so it won't matter how many bump stops you have but too little bump stop protection could cause damage to the suspension. I would ask the vendor for their recommendation. Good luck.
I like the name sounds very important 👍
I have a 96 chevy Silverado c1500 and was wonder why when I hit a hard bump or dip in the road I hear a thud like it's bottoming out. Brand new shocks summit racing 2 inch lowering so the truck sits level in the rear to match the front which looks amazing. I have been wondering if changing the bump stops would prevent the thud that I hear when going over big bumps or dips in the road?? Any help would be greatly appreciated. Thanks in advance. Joe
It sounds like you know what's going on intuitively - you're likely bottoming out. Lowering without sufficiently increasing spring rate, and considering Flat Ride, and properly addressing HOW the SHOCKS behave will almost always lead to problems.
As I just replied to someone on the E90 Bilstein video where I showed how to access the internal bump stop, bump stops matter but the dampers also matter and total suspension travel really matters.
I helped a customer who had a Miata for fun which we upgraded then later work on his Ford SuperCrew for work duty and family trips. He wanted it lowered and able to handle sufficient load but also have a decent ride for long trips. It took a while to get things dialed on springs, how many leafs, heights, etc. but in the end he's happy. A key ingredient was making the dampers work right as he tried off-the-shelf Bilsteins and they just weren't very smooth.
I don't know what 'brand new shocks' means or how what you have works. Unless you ask the right questions from the shock vendor you won't get getting a trophy truck / baja-style upgrade. What I mean is, you'll have looks but not a better ride or help avoiding bottoming.
The best help I can offer is to find out on forums if someone has gone your direction and had success. My services are high-end so this is the only free advice I can give you. If you want to engage more you can send in a consultation form and make a 30 min payment here: www.fatcatmotorsports.com/fcm_elite_consult_form.htm
If I use lowering springs would a high quality bump stop reduce or stop me from bottom out on dips or bumps?
A high quality MCU bump stop would reduce the severity of bottoming out. You'd also want to make sure your damper (if adjustable) isn't biased too much on rebound (which causes even MORE bump stop contact and increases the frequency of bottoming out). The damper is really a crucial factor in how often and how severely you run out of suspension travel, although you need to not be running too low a height for what the springs can support. The bump stop can help, but I wouldn't overly rely on it if the damper is strongly rebound-biased or the springs aren't stiff enough to reduce suspension deflection.
I had my bump stops cut 25mm from the bottom and reused the upper portion after installing tein lowering springs. I didn't like the ride quality and returned back to stock, is it ok that my bump stops were not replaced back to original and currently using shorter length than before? Thank you.
In terms of function, cutting from the bottom is usually the wrong place to trim since the 'progressive nose' is removed and you get more of an 'on/off switch' behavior from the bump stop. I generally hate lowering springs as well, since they are invariably too soft for the amount of lowering (too much).
Being at a higher ride height makes a lot of difference, eh? If you are okay with the way the car rides with the cut bump stops, then I'd say you're fine. My own thought is making sure you have enough protection with the cut bump stop but if they were stock bump stops originally then I imagine you still have 30-40 mm of bump stop remaining.
Exactly feels too soft especially at high speeds and bumps, I end up bottoming out compared to when i was riding stock. Are lowering springs softer than stock springs? Does it mean that lowering springs are just comfortable at low speeds and less bumpy roads? Will coilovers solve the problem of bottoming out since its spring rates are stiffer and i will end up bouncing instead on such bumps instead of bottoming out?
Lowering springs emphasize looks over function. They are typically 20 to 30% stiffer than stock springs but the amount of lowering they give (usually over an inch) is too much for that small a spring rate change. So you are into the bump stops more often than with factory springs, if not already riding on them at static ride height.
In my experience and understanding, having an appropriate spring rate (often double the stock rate or more) and height adjustability via a coilover will give you sufficient spring rate to avoid constant bottoming out. However, if the coilover setup doesn't have Flat Ride or if the damping isn't tunes correctly then the coil overs are not going to work and the ride will be more uncomfortable than before.
It's all about having the elements work together which is why I talk about Ride Harmony and Race Synergy. If you wanted further assistance you can contact us through the website and schedule a consultation to discuss options.
I have a question should you bump stop be remain firmly at the top?. My bump.stops slide up and down my strut freely but not sure if it is correct or not?
I haven't found a floating bump stop to be an issue, however it's a good idea to use a dust cover / dust boot /gaiter so you aren't introducing more dirt and debris between the bump stop and the shaft or seals that could cause wear.
Do i need to slice the bump stop thinner after installing coilover? Because i feel like the rear is quite bumpy, despite adjusting the dampening and also using a 5k spring at the back
I'd ask the people who made your setup why it's so bumpy...
If the damping isn't right then cutting the bump stop may only reduce some of the bumpiness. It could also damage your dampers. Impossible to say without knowing a lot more about the setup (consult form) and having a consult payment. Without a damping change, any setup I've seen will either jack down (too much rebound) or launch (too much compression) with the former more likely. The bump stops are part of the situation, but not a 'cure-all.'
There is this simulator called assetto corsa competizione. Official Blancpain GT3 sim , and actual GT3 drivers say its pretty realistic as well like David Perel. In the sim in the aggressive setup preset almost every car has very little bumpstop height on front but like 20-30 times bumpstop height at the rear. Why are they running it too little on front and too much on the rear
Interesting. I can think of a few reasons. How about you watch the "Tuning with Packers" video and then reply back with your own ideas as to why the GT3 may work that way?
th-cam.com/video/HV6fgwCjZ2E/w-d-xo.html
And part 2
th-cam.com/video/uikpAQB6IYA/w-d-xo.html
Suspension Truth by Fat Cat Motorsports, Inc. Thanks a lot for replying. I watched your videos and im amazed by your knowledge , your channel deserves way more subs. I also scrolled throught ACC forums to see if they had any discussions about this same thing and found out that somebody already asked it and one of the devs replied to him and linked a video he made about this. th-cam.com/video/iQ1guCnrv5Y/w-d-xo.html So basically reason why they run so little bumpstop range in irl gt3 cars is because of their aero pitch sensitivity. When braking center of pressure moves heavily to the front and can throw the car off if you are not really careful while trailbraking. And reason why they run so high bumpstop range at the rear is because of they want traction over kerbs and bumps on the corner exit. Lot of the tracks in blancpain gt3 calendar have lot of bumps and kerbs especially zolder. And i want to thank you again for making those videos , i learned lot of stuff just by watching those 2 videos that you have made.
You answered your own question, kudos! Bump stops are a very important part of tuning on many cars; they can be used very intelligently, while some vendors choose to ignore (or omit) them. The flexibility of the setup suffers when all the available tools aren't utilized. I also know that some vehicles (including some Porsches) have used internal 'rebound stops' - that's another interesting feature which I'd be curious of the ACC software allows for! Things get trickier with setup then... VERY ride height dependent and harder to tune vs. bump stop length (or range as you say).
Suspension Truth by Fat Cat Motorsports, Inc. internal rebound stops on the porsche are on their road cars right? Im not sure but maybe gt3 regulations dont allow them. But i ll ask the devs if the porsche 911 gt3r has them too and whether or not that exact thing is implemented in the sim
I'd be surprised if regs would restrict internals beyond preventing active suspension (which I presume aren't allowed, like F1). But, tuning is tricky as I said. A late 2000's Cayman S I improved had internal rebound / droop springs on the OE struts.
Do you have a Bilstein part number for front strut bumpstops? Or a source? All bump stops I can find are too large a diameter to fit within the bilstein strut.
You will need to call them to clarify p/n and order. From my part notes I see a 'soft'-density bumpstop as E4-AP2-Z045A09 and a 'medium'-density as E4-AP2-Z050A00. I've used both inside strut housings. Good luck.
@@SuspensionTruth Thank you very much!
hello can I ask? can a worn bump stop cause tire rubbing? hope u can answer my question because my tire is rubbing when it hits a bump or an uneven road with or without a passenger🙏
Yes if there is insufficient bump stop material / degradation you could get rubbing.
I have eibach coils so it raises my vehicle like an inch and now my front struts bottom out on speed bumps. Would those packers help out and if so how thick would they have to be?I have one inch ones but havnt put them on yet.Would this solve my issue?
I've never heard of eibach springs 'raising' a car - sounds more like it lowered it, and you're bottoming now. I'd contact a professional mechanic in your area and get their advice. If you don't use a proper coil-over system, you're going to run into problems like this. 'What lowering springs should I get' is a video I made - watch it.
I think this the problem with my 8th gen civic after brand new shocks and car is so hard in tiny holse but very good on big speed breakers
Good on bigger and hard on smaller sounds like too much gas pressure in the damper. New dampers often need some time to break in, especially if they are monotubes. But if you're concerned have a qualified mechanic check things out.
@@SuspensionTruth ok thanks for big help.no im not a mechanic but im trying to understand things by your videos maybe one day ill be able to fix my car by myself.thanks a lot
Are bump stops supposed to be loose over the strat shaft or seated sold?
Some are loose, this is fine.
First video I've ever smelt 😬🤧😲
Does water and dirt damage foam rubber bump stops ?
Foam and rubber are different things. BOTH rubber and micro-cellular ("foam") MCU bump stops will degrade with dirt and abrasion. The higher quality MCU lasts longer. Rubber lasts longer still but is very hard and is a poor bump stop material, hence why rarely used now.
So most cars should have bump stops on all struts and shock if you’re able to put them on? (Lots of shocks have the eyelet on top and bottom I guess like a sealed unit - sorry I’m a newbie-intermediate)
Yes, some kind of bump stops adds protection as well as tunabilty to the suspension. For an eyelet damper you'd need to carefully heat the bushing housing near the shock shaft to warm up and loosen threadlocker.
Then clamp the shaft with soft jaws (ideally in a shop press) and use a long 3/8" or similar extension through the eyelet center to rotate the eyelet housIng free. From there you can service the damper and also change / replace a bump stop. I'm not sure I've done a video on this...
Very nice explanation/analogy.
Thank you.
Hello.
I planing install a sport suspension(lowering shocks and lowering springs). And thinking what to do with bump stops..🙄 need a cut or not ?? They are standart.
Ask the manufacturer of your lowering spring kit and watch more videos to continue educating yourself.
2 year old video. But It was cycled.....
The bump stop helps to not blow the shocks .limiting the mechanical failure. Nothing to do with passenger ride really at all. It's about helping the shock survive the forces ,exceeding is intended design.
Good video...."butt!"
Close but not completly. If the bump was about not bottoming out then they would just put a stiffer spring on the car. Bump has a lot more to do with the caster camber gain and the maximum grip curve. Not destroying the suspension is a byproduct of that.
Both comments have elements of truth. Bump stops are used to protect the suspension components at full compression, also keep the chassis from bottoming on the ground (also chassis bump stops come into play here for some cars), also to modify the handling behavior (usually toward more front roll stiffness = more understeer), and also to manage having more passengers or more cargo.
Is it a problem if the bump stop is loose? (I'm able to move it up & down with my hands
Never seen it be a problem to be loose in terms of function.
However, some OE bump stop are designed to have a dust boot attached bump stop ID is sized to stay on the shaft near the top of the travel so the dust boot covers the shaft.
@@SuspensionTruth Thank you
I have CRV 2002, and when it is on bump r dump feel like a trailer which have no shock absorber r Sturt. Even a smal stone under the tyre shake my car. So what is the reason?
Sorry for language
I really can't say without more information. It's 18 years old, so the struts / shocks could be worn, the bump stops could be worn / degraded, suspension bushings worn / degraded. Many possibilities. I suggest you take your CRV to a local mechanic and have them inspect it. Good luck.
@@SuspensionTruth
Thanks for giving me your time, I did that and the Sturt and dump stopper was bad, so I changed the Sturt. Now I feel good. The car is also smooth now.
Hi,if bump stop damage,will it cause squeaking noise?
It could. More likely you'll hear banging sounds if the suspension bottoms out. Squeaking could be from bushings that are worn out or not lubricated. Get help from a mechanic if you're unsure how to diagnose.
does it give more or less comfort on a lowerd sport suspension?
i want more comfort
The suspension needs room to work properly, to give good comfort AND to give predictable handling. Lowering any vehicle without careful choice of spring rate, damping, bump stops and other variables will make the car LESS COMFORTABLE. Changing out bump stops MIGHT help but will not fix other problems caused by lowering.
If you´re here for racing sim, give a thumbs up
Cool, realistic driving sims using bump stops now..?
@@SuspensionTruth they have been for a while, bro
Where can I find one for an rsx?
Assuming you have a strut up front (~19-22mm OD shaft) and shock rear (12-14mm OD shaft), you can get a pair of 47mm Speedthane strut-style bump stops FOR THE FRONT and 58mm 'red' shock bump stop FOR THE REAR from a variety of places, including 5Xracing.com (my distributor for FCM bump stop kits). The Mini Cooper R56 kit would likely work for your '04 RSX but measure/check the the dampers you have to be sure.
@@SuspensionTruth Which one to the front?
I edited my original comment - re-read that.
Ohhhh
Can the bump stop change ride height of a car??
It shouldn't, unless the bump stop is excessively long!
Nope....Spring Load decides Ride height
@Satya Chandu, if the bump stop is ENGAGED at static ride height, then it WILL increase the ride height. Otherwise, if there's no bump stop contact at static height then there's no height change.
Will no bump stop cause car to be bouncy?
It could be bouncy, crashy, bangy - it's not a good thing to run the majority of cars without bump stops.
Someone just replied to this comment but I accidentally removed instead of approved it (YT holds certains comments and I don't dont have manually set to approve). Please repost if you see this.
2004
So bump stops don't stop bumps. 😀
They are brakes, to keep your dampers from breaking.
Mashallah
Shukran, Habibi.