Ohlins Suspension - Valving Basics #2 - Bleeds
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- เผยแพร่เมื่อ 27 ส.ค. 2024
- Ohlins Suspension-Second video in a series on valving. Exploring bleeds. What they do and how to use them.
www.brennershocks.com
Instagram @brennershocks
theohlinsguy@gmail.com
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Thank you for the information. This is the first place ive found great knowledge via video on this subject. ive Ive gotten all the knowledge i know about revalving through the racetech book and buying gold valve kits to play with and try and figure out.
It seems like good suspension techs keep all this way too close to the chest, treating it like black magic. So i really appreciate you letting people who want to learn, do so without taking an apprenticeship at a shop.
I think "suspension techs" keep it close to the chest because they really don't know what they are doing. They have to make it mystical and complicated to dazzle you with their brilliance. It is not rocket science. It is hard to figure out what you are doing without a dyno but just keep at it and you will figure it out.
great info on the evolution of shims and bleeds!!! Thanks Doug, really appreciate your effort putting it all n the video in such clear manner
Thanks! I try!
this is the best content i have seen in youtube about bleeds. very clear and informative.
Thanks!
That's some informative content you've got going on there Mr.It's really helping with my understanding of how to tune my own dirt bike suspension beyond just twisting dials. Thanks and Keep em coming!
Thanks Rick!
This guy is amazing. Thanks for the info in such a consumable format.
Thank so much for explaining. I like your video's. You are in business and willing to share your knowledge. I appreciate.
Thanks! Glad it was of interest to you.
Thanks for making these videos, very informative and good watches. Keep it up
Thanks. I am out of things I actually know about!
Great videos. No one shares this info like you do. I’m in the off road desert race world, bleeds are usually jus drilled holes. Cool to see different options. Thank you!
Yes, I like internal bleeds with no adjustments. Thanks for the kind words! Douglas
Great video. and thank you for your time. I have raced dirt cars for 35 years and have rebuilt and valved my own shocks for most of my racing career. I don't drive anymore I just help my son who races open motor late models and other drivers and try to pass on a little bit of what it took me a ling time to learn. Who knows I may need parts in the future and we can talk. God Bless and again thank you.
Thanks!
really interesting content. It's so great to have access to this information. Thanks again for another really educational video.
Thanks John!
I feel like i should be paying for these videos
Very kind Aaron but you probably have way better things to use your money for!
Very very good information 👏🏾👏🏾
Thanks! I try
Hello and thanks for investing the time to share your knowledge!
I have a question regarding "internal bleeds" with regards to designing/engineering the "dyno graph". As I understand, for a shock without an externaly controlable bleed ("clickers") there is a need for a "constant" (not variable, like the external clickers) bleed.
Can you please elaborate on why there needs to be some bleed and you cannot work without any bleeds? And how does the influence of no bleeds or some internal constant bleeds show up on the dyno? Where there is more influence with regards to velocity of the shaft, where there is less influence, etc.? Essentially, what I'm trying to understand is, what type of a "problem" (or rather a curve geometry) on a dyno chart a constant internal bleed can help to resolve?
Thanks!
A bleed is pretty much low speed damping. You can run without bleeds but it makes the damping very digressive. Bleeds also allow pressure to be relieved that has built up in the shock. If the bleeds are closed you get lots of hysteresis
Thanks for answering, this is exactly what I wanted to know.
Just to recap and be sure I got it right - the most influence any time of bleed will have, whether constant internal or externally adjustable, will be at the lower shaft velocities varying the dyno curve (that is, changing the character of the curve) at slow shaft velocities from a somewhat flat or even progressive (what I mean by progressive is non linearly increasing damping force with increasing shaft velocity) to digressive whilst only "shifting" the curve up or down relative to some "midpoint" at higher shaft velocities?
🙏🏼 thank you
Hey Douglas, great videos! I think I finally start understanding how shocks/forks actually work. I've always wondered what it actually means if they claim (from the outside) adjustable rebound and compression in a 20/80 ratio (I saw this with MC forks). Am I right this practically is a bleed like the 5666 24? Fully open one direction and less open the other direction, thus the adjuster closes the bleed valve which effects rebound/compression with its different openings for either?
I always wondered about these shocks identified by ratios. 20/80 of what? How much damping are you talking about?? I think bleed is just the topping on the cake. In most shocks it is not very powerful and messes up pressure balancing. Valving is the way to change things
Thanks, I realized I didn't understand that each side of piston was blocked by a shim
Yes, pretty clever. One side compression and one side rebound. Thanks for watching
Hi Douglas, thanks for your great videos, extremely helpful….. Please could you advise me what nitrogen pressure is recommended on a STX46 shock number AP8271 Aprilia RSV 1000R Factory bike? Thanks.
Hi Peter. 12 bar (175 lbs)
Good stuff man!!!!
Thanks! I try
Thanks for your times and effort you put in your channel! What a great info's! I have looked all your videos a few time already.
I do have a question if you don' t mind.
Can we run a clamp shim behind the 1st face shim to act as a one way valve?
38.25 (or thinner for more bleed?)
20.? ( play on the thickness for + or - bleed?)
38.25
34.25
...
Or just as you said shims with holes or a clamp shim at the top to get the bleed both way will be better?
Its for an off road motocross looking to get less damping on roots and rock (wheel deflection).
Thanks very much for your time.
Hi Marty. I am not sure I understand the question. If you want to make the bleed around the piston one way or not equal I think the only way you could do it would be change the shaft jet. If you get the same ID and length jet you wouldn't have to change anything. Let me know if that is what you meant.
Great video. Thanks!
Thanks for watching!!
It seems without sufficient bleeding the low speed damping causes the sharp rise in the graphs until it levels off. Is a linear line the goal? What does the point where the lines connect affect when it moves up or down the graph? Does an offroad configuration look significantly different on the graph than on-road?
Hope this isn't too many questions. I'm in the process of watching all your videos and learning as much as possible
I am not sure I totally understand the question but I will answer and if I missed something let me know. I think closing down bleeds can cause a low speed spike but more than that it seems to cause hysteresis. TTXs don't seem to be as sensitive to closing down the bleeds. My opinion is that once the damping is correct that it would work on and off road. I would think that digressive damping and closed bleeds would be more of a problem off road.
So does a "shock man" in a dirt late model trailer go crazy trying to get the valving right on a really bumpy track. I'd expect so with all the different ways to go about setting the rebound with I think would be more important than compression. I had to look up hysteresis.
Hi Ralph. Rebound is the enemy of grip. Also if there is too much rebound and not enough compression the spring could be pumped down and preloaded which would make it even bumpier. I believe once you get the damping right it is good on a smooth or bumpy track as the damping depends on the velocity of the shaft.
This was very interesting. One thing remains unclear to me: at around minute 17:30 you’re discussing slotted shims. As far as I can tell they are free to rotate around the rod, so how do you control the position of the 3 slots relative to the 3 piston ports? Thank you Sir, greetings from Germany.
Hi Vi Great question! Once the shims are tightened on the piston they can't rotate. The trick is to make sure they don't rotate while you are tightening the nut. I always look to see that the slot is over the port after I have tightened the shims.
@@theohlinsguy4649 I see. Interesting because in the automotive industry it is usual to have „poke yoke“ features which basically prevent misassembly by design. Which comes at the cost of flexibility, but that’s not what you want when producing at large scale. Please carry on with the great videos, it’s such a pleasure to watch.
Where do I go to learn the math and calculations behind everything? Shock movement vs wheel movement ratios...etc?
I think I have gone through the math that I know in my video "know your motion ratio". I learned it all from my mentor Bruce Burness. I would be happy to help you with any math that I know. It is all pretty basic math. I know that because I can do it!
With shock movement vs wheel movement (motion ratio) it is pretty straight forward. Say you move the wheel up 1.5" and the shock shaft moves an inch. You just divide the shock travel by the wheel travel and you have the motion ratio. shock travel 1" divided by wheel travel 1.5" = .66. So that is the basic motion ratio but you have to square that to get a number you can calculate with.
So .66 x .66 = .435. Lets say you want to know the wheel rate (what the wheel thinks your spring is). Let's say you have a 150 lb spring. Multiply 150 by .435. The wheel rate is 65 lbs. Lets say you want a certain wheel rate, for instance, 150 lbs at the wheel. Take the desired wheel rate of 150lbs and divide by the motion ratio squared of .435. You would need a spring of 344 lbs to get 150lbs at the wheel.
Can't we just leave all the ports open for bleeding the pistons?
Hi Brian. You should always bleed the piston with adjusters open. You need to make sure that the needle valve is pushed down all the way. It is hard to hand bleed with a one way bleed circuit as it becomes difficult to bleed in the direction that the bleed circuit is closed. With vacuum bleeding this is not a problem. I only use open bleeds. I don't know if that answers your question. If not let me know.
Hi sir how are you?
Iam Ejaz from india
I have question.?
How could we do bleed in without adjustable damping ? Without additional hole in piston
There are slotted shims and also you can put a small washer of various thicknesses under the sealing shim