4 Link 101: Offroad Basics
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- เผยแพร่เมื่อ 24 ม.ค. 2022
- This video scales a rear 4 link set up for a 4x4 off road rock crawler or Jeep, down to 1/10 scale to help show the motions of the axle and pinion throughout the suspension travel. This video shows various changes to the 4 link design, and illustrates the outcome of these changes.
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Crazy as it sounds, This helped me with my RC Four-Link setup. I had way too much Anti-Squat.
I thought this was an RC video at first lol
And i am confused because many RC crawler informations suggest to mount the upper links higher.
Lol helped my with my custom high clearance links on my vanquish fordyce rc crawler
@@snorrevonflake I assume they're trying to maximize articulation in doing so, but I really don't know.
This is why I’m watching this.
Thanks, great simple explanation with an excellent visual aid. This is a big help on grasping the basics.
This is awesome information and will apply this on my rig 🤙🏾
Awesome everything thing I experienced in building offroad cars in one video. You figured it out and shared. Easier on paper and graphs. Than a ton of steel and hours of fab and then go back to the drawing board. After it wipes everything out due to driveline angle super important. Most critical part or it takes the fun away if it isn't right. Thanks for sharing.
I’ve always been told 4 link is good for off-roading, but I’ve never understood why or how they actually work. Thank you for this video. It’s very interesting! You did a great job putting the info together in a way that’s easier to understand. I appreciate it and well done!
The original CAD (Cardboard Aided Design) in action!. Great demonstration to help visualize the movements and angles that result from different configurations.
However, it would be kind to your viewers to remind them that if you design the links so that the diff pinion shaft is always pointing towards the transfer case, you need to use a double universal joint at the transfer case end of your driveshaft. If you have a simple single universal joint at each end, the transfer case end UJ will be swinging through a wide range of angles while the diff end UJ stays fairly straight: this will cause rotational speed oscillations in the driveshaft that will not be offset by the second UJ, leading to vibration and shortened service life of the diff components.
Nice information and explanation, thank you. Agree with you that the link calculator is to "technical" and hardly takes pinion angle into consideration. I have an ongoing SAS on a Nissan D21. I did a radius arm setup on the front which I would like to upgrade to a 4 link (3link + Panhard), and have attempted to match the arm length to the the same as the driveshaft. This eliminates big length changes on the slip joint through the arc of travel. I am now kinda setting up to upgrade the leafs on the rear to a 4 link coil suspension, and will be basing my arm lengths on the driveshaft length again. I also like the parallel same length upper and lower arm setup, as the vehicle is also my daily drive, but is a handful with the 6" lift and 2" bigger rubber. I am suffering driveline vibes already, and hoping that adjustable 4link will give me the ability to adjust things to dial out the vibrations. This video was inspirational for this noob... Thank you.
Thanks for all information. Learned a lot. Like the idea of you modeling
Great video !
Thanks
This was awesome
Thanks for the explanation, I’m going to build my 4 link now.. I have little experience in fab, but have some buddies.
Super helpful. Thanks man!
Thanks, that helped me more than the calculator ever could.
Its not about getting perfect numbers. Even if you use the calculator, its never accurate. Because every rigs center of gravity varies. And it all depends on how accurately you measure everything to plug in all that info. Totally unecessary. Just triangulate the uppers and lowers, and follow a few basic rules and itll work out fine (unless someone has no idea what they're doing).
Awesome diagram and very helpful!
Thanks man. I think im going to do more like this.
Designing an rc crawler and this helps me more than rcc tutorials
Thank you very much for this video, it is super explained and it is understood like no other, could you make one like it on the location of the cooilovers?
I sub'd so I can see more videos like this. I love how this can also apply to the 1:10 crawler world. Thanks for the informative video.
I intend to make more tech vids. I took 2022 off from wheeling and bought a house. Ill hopefully get to make more soon.
@@wheels.and.wrenches I cannot explain to you how helpful this was for my 1:10 crawlers. Your visual aid is BY FAR the best I’ve seen to help me understand 4 links. Thank you.
This was fun
I run my rear measured eye to eye square not diagonal 31" lowers and upper wishbone. Upper and lower are actually lot longer than 31" because triangulated. I have around 31" running length driveshaft on sye.
Good stuff right here!:👍
Im convinced uppers and lowers exact same length. Lowers 7 degrees. Uppers slightly higher at the axle with an adjustable chassis bracket is hands down the best option
@@wheels.and.wrenches I'm planning on building a triangulated for link for a mud truck in the near future. I'm looking for all the advice I can get.
great explanation.... I like it, but now i want to change my setup :)
Obviously double triangulation is important for a rear 4 link. It's much more stable than a single triangulated set up. But the angles of the links are the most important of all. Front 3 or 4 link its important that the pinion points at the case throughout travel, to keep caster in check. In the rear, its more to keep the rear driveshaft U joints from binding during droop. Regardless, if you keep your lower at 7-8 degrees, and build your upper parallel with the ground and slightly shorter than the lowers. And use a 4 hole chassis mount for the uppers, eveything will be within spec and adjustable. Cant go wrong following a few simple rules.
Heck ya.. awesome. Can you do the same on the back view or pinion view explaining with shocks and articulation?
Nothing related to shocks and articulation changes much. The shock angle changes slightly throughout travel. Thats about it
I have been wanting to do something like this for ever! Thank you for saving me a $#it ton of time! I want to go long arm on my TJ but not sure what to go with... 3 link, radius arm or try to stuff a 4 link in it. and how long can I/should I go. (builder kit kinda deal).
Step 1: Weld brackets on the frame where they need to go.
Step 2: Weld brackets on the axle.
Step 3: Measure for links and build links.
3 link is fine. Make sure your frame is plated before you weld your upper link bracket on. The upper link mount must be very strong and the welds need to be very strong. Because if that bracket breaks, ita gonna cost you thousands
@14:35
I believe that’s actually idea for the front axle. You want to keep your steering straight.
And what about 4 links setups used in off road racing (baja 1000, baja 500, vegas to reno, etc.) is the geometry any different? do they only use tougher components? do the mounitng points at the axle change? I'd appreciate any help, thanks.
great video BTW, super helpful
Totally different suspension set up all together. Rock crawlers are going less than 5mph. A million dollar trophy truck is going 120mph with 30" of travel. Two totally different sports
They usually have trailing arm setup in the rear and ifs front, if no ifs front it's a very sophisticated link setup because caster angle and steering performance is super important
@@mazevx2451 thanks
I want to make a tool like that for experimenting with setups.. 3D printed maybe... 🤔
Awesome video. Do you have recommendations on doing reverse triangulated 4 link? Upper arms going to rear bumper.
I would most definitely not do that lol.
The Pinion angle is not the only thing to consider.
For most the Pinion angle pretty irrelevant because a not rockcrawler vehicle will be 98% on ride high, probably more.
The interesting part is, how smooth one goes over obstacles! And also dive when braking.
This is a rock crawler channel 👍🏻
On a RC crawler that is trying to do max steeps and sidehills in a more controlled lighter setting than 1:1 where speed and weight cause a lot of stress.
Rear links a lower link parallel to the ground is ok right…with upper parallel and higher with max diff in heights. When lengths were and same and if mounted to similar location will maximize the pinion being lined up?
Pinion angle means nothing in suspension performance. All it prevents in the rear is U joint bind.
In the front, the pinion angle is WAY more critical because pinion angle and steering castor are directly related. But none of this relates to RC cars
With rock crawlers do you have to use a double U-joint on the transfer case? On street cars the idea behind parallel links is to keep the transfer case and pinion parallel, even if the pinion isn’t pointing at the transfer case because the second u-joint removes the vibration of the first.
So it seems like the idea is to keep that u-joint angle from happening in the first place. But it would only work for the differential’s pinion and the u-joint at the transfer case is still working hard and the u joint at the pinion wouldn’t be able to cancel out the vibrations unless there’s like another u-joint somewhere😂
The parallel links have nothing to do with pinion angle. Thats all for anti squat numbers in the rear on street vehicles. Pinion angle change only applies to long travel off road applications. Any 4x4 with a double cardan rear driveshaft, the pinion should be pointed at the case at ride height. Any 4x4 with a normal single U joint rear driveshaft, the pinion angle should match the rear transfer case output angle at ride height.
@@wheels.and.wrenches Ok very helpful. It’s not a problem until you start getting large angles. I do think parallel links will keep the pinion angle the same throughout it’s travel, although increasing the average angle of the individual u-joints.
Since this is a 2 dimensional model looking from the side, if you built a 2 dimensional model from top looking down wouldn’t the upper links be triangular? So keeping the distance from lower and upper frame mount the same distance apart front to back cause the upoer link to be longer than in the 2D side view model?
I hope that makes sense?
Both uppers and lowers are usually triangulated in crawlers. Unless you're running Trailing Arms in rear. The offset forward to back in where the upper link mounts to the truss, is around 6" further back then where the lowers mount on the front of the axle tube. You can run the exact same length links uppers and lowers, and the upper will still appear shorter because it's set back more in the mounts. Most people run slightly shorter upper links it seems.
I have a jeep JK. In the front the lower control arm mounts hang down a lot. What would happen if I were to move them up about 2” inches and leave the upper mounts put? (It’s my daily by the way).
It would improve your lower arm angle. As long as your vertical upper to lower axle mounting points are 9" to 10" separation, its fine.
Just dont tip your front pinion up too much.
@@wheels.and.wrenches from factory is has 9 inches of separation. So if I raised it it would be 8” inches. Do you think this is enough to cause any issues or drivability characteristics that would be noticed
@joerouth6255 separation should be 25% of your tire size. Id want at least 10"
@@wheels.and.wrenches and if it’s less do you know how it would affect drivability
Hey man, I man so interested in building something like this but with a triangulated 4 link rather than what they have which is 5 link setup. Any tips on how I can nail the suspension geometry with something like this? I would be happy with 12"-16" of travel really. Not going hardcore. Please help. I'm new to these stuff.
This stuff isnt the type of project you want to take on unless you're an experienced fabricator & welder. Who has years of experience building off road rigs.
@@wheels.and.wrenches yeah that is why I want to learn it right now. Gotta start somewhere.
@@wheels.and.wrenches also, I can always look for people who can do the fabrication for me. It's the geometry and the design I am most interested in.
Also having equal length links means you could have 1 replacement part that could work in either location
That would come in very handy
What’s your thoughts on removing rear steer from a 4 link
Rear steer is caused by your links being too short and not at 7 degrees like they should be.
Hello, I want to install a 43 link in a Trailer I going to use for offroading, Because there is no DIFF just a n open axle, is it still need ed the 25 % tire dimension separation between lowe and upper ControlArms?
I cant get a 7° on the lower CA, is it an issue?
should say 4 link
Theres no power being delivered to the tires. So the axle isnt under any rotational load... vertical spacing at the axle doesn't matter. A trailer with a 4 link will be unstable as heck. Id just go with a stock used/flat leaf spring, kinda like a stock Chevy square body leaf... keep it simple. It's just a trailer.
Any way you could illustrate a top down view of how the four links lengths and angles all react?? Sounds hard to do but would be cool!!
4 link angles looking from the top down dont do anything except provide lateral stability of the axle. The more triangulation, the more lateral stability your axle will have. Thats why 4 links dont require a track bar (pan hard).
Apparently all 4 link.The bars are supposed to be in a straight line with the vehicle or square.If you will a top down view you would see no movement at all unless you screwed up somewhere far as angles
I'm sorry Google Voice typing.I didn't mean to say in a parallel four link A triangulated four link would maybe have some side Two side angle variations with articulation
Got me again but I think you understand what I'm trying to say
simple math this. it's all about arcs and positions that effect it, you can have a shorter top arm, but you must separate the povit point on the axle more. so short arm, long distance between pivot points, long arm, close pivot points. Also it's obvious that the higher the top arm chassis fix point is the more through the arc it is so will point the diff nose down at full droop. you don't want that in any scenario as it over extends the capability of the UJ's or CV joints.
The separation at the axle is always going to be approximately 10-11" vertical and front of the axle tube to center of the truss (Front to Rear). These aren't going to change much. The upper arms are always going to be offset to the rear because of the diff is pointed upward due to the pinion angle.
But what if I want to put the lower link of the rear suspension parallel to the ground, and achieve 90-95% anti-squat? Do I need to mount the upper link on the rear axle higher, and make the front mount on the frame lower than the horizon?
Thats not possible unless your belly height was 15" off the ground. Your links would hit on every rock and you'd be hung up every 2 minutes on everything on the trail.
High antisquat is BAD for offroad. You're thinking of it backwards. Parallel links create a VERY low antisquat number. Meaning the ass end WILL squat, which is more of a drag racing set up for weight transfer to the rear if thats what they desire for traction. Most people want a happy-medium mid range antisquat number. Every application is different and trail & error is required.
@@wheels.and.wrenches Then why are the stock Jeep Wrangler Rubicon and Ford Bronco rear lower link parallel to the ground?
I’m totally mocking up my numbers and doing it on paper.
Pinion angle yes stability and climbs, what’s best angle
Theres a couple simple rules...
Keep your lower links around 7 degrees.
Make your upper links around 90% the length of your lowers.
Make your upper links 0 degrees with an adjustable chassis mount.
Triangulate both uppers and lowers
How much travel do you have on your rig? I heard the length of the lower arms should be the double of your travel is it true?
Thats not true. Most people will be runnings 14" shocks all around. I run 14" rears, 12" fronts. Your lower links are always going to be a minimum of somewhere around 34" to get your link to sit at 7 degrees. Most peoples lower links are in the 38"-42" range eye to eye. A 28" link would never sit at 7 degrees... its too short.
@@wheels.and.wrenches thanks. So I have to try to be as near as posible yo 7 degrees?
@@oscarneder2656 it explains everything in the video
@@wheels.and.wrenches sorry. I didn know the 7 degrees was a constant i'll watch the vídeo again.
@@oscarneder2656 It's not.
The lengths are visual lengths from the side right? Not the physical length end to end.
There's no such thing as a visual length. The ONLY way to measure for a link is center bolt to center bolt.
Why isn't the ideal setup to have the pinion angle always the same as the transfer case angle? Isn't having the top and bottom U joints at different angles not ideal? I'm talking ideal, not necessarily what you'll have to compromise on.
Because the pinion angle is always changing. Its not important. You need your suspension to perform properly for traction, travel and ride quality and lateral stability. As long as the U joint doesnt bind up, thats all matters.
How come you didn't test with upper links longer than the lower? That's how I'm building mine, it will keep the pinion angle truly pointed at the transfer case. Links the same length just keep the pinion the same angle relative to where it swings, not pointed at the transfer case as it raises and lowers.
Because upper links are never longer than the lowers.
@@wheels.and.wrenches why, it's going to blow up?
@Zach Fairchild thats not how it works. Research and build 4x4s for 30 years, then get back to me 🙏🏻
@@wheels.and.wrenches then explain what problem you get when the upper links are longer than the lowers besides less anti squat. How long was the "rule" that uppers are 75% the length of lowers?
I’m just going off of head geometry, but I’m pretty sure having the upper longer would make the pinion arc in reverse, pointing down away from the TC on droop, and up above the TC on compression. But, it all depends on the angles and setup.
Lifting my 2011 wrangler 2 inches should give it some caster , without changing suspension links .
Castor should remain as close to stock as possible at all times. You CANNOT tip your front pinion up because that inversely tips your knuckle/steering plane into the ground. And this causes death wobble and other horrible things.
@@wheels.and.wrenches Putting in 2 inch spacer lift . If the caster increases , i'll put in adjustable upper links to correct it .
Caster isnt a thing you get. Its a degree measurement of the steering knuckle plane in relationship to the ground. Factory straight axle rigs come with 4-8 degrees of positive castor at ride height. That means the knuckle laid back 4-8 degrees of Positive castor. So the knuckle steering plane isnt steering into the ground. When you lift a vehicle with short arm 4 link too much, the short arm geometry gets all out of whack and starts to tip your knuckes forward, which puts a bad castor angle on the knuckles. This is why short arm lift kits come with "adjustable" lower control arms. So you can lengthen the front lower control arms to correct the bad castor angle.
A 2" lift isnt going to hurt anything. Its when people used to try putting 5.5" lifts on TJs and XJs back in the day with short arms they got into trouble with castor and death wobble issues.
@@pennyhelga3628 adjustable lower links. A 2" lift isnt worth buying. It will barely be noticable. Get a good long arm lift that will clear 37s
@@wheels.and.wrenches My kids gave it to me for christmas . I bought shocks and other parts . I don't want it real high . Only running 33 inch tires .
Another guy said the upper link should be 70% of the lower.
Thats too short in my opinion
Get a jeep
I own a Jeep lmao