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Old 11-23-2009, 06:16 PM   #1
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Questions?? Shock Compression/Rebound rates

How much compression/Rebound do you run on your shocks? Ive always run my shocks with full compression (till eyelet hits shock body) and full rebound but recently I been tolf full rebound is a bad thing since your basicly "over preasureing" the shocks dammaging them and causeing a leak so were do you like to run your shocks. im sure there is a big diffrence between the sedans and T/A but it would give me some ideas
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Old 11-23-2009, 06:45 PM   #2
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I always run full compression, but rebound depends a lot on how the grip is that day, and what the track design is.

On a side note, running full rebound will not damage your shocks in any way. When you place the bladder on the shock, excess oil comes out so that prevents having a shock that has too much oil in it.
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Old 11-23-2009, 07:41 PM   #3
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I like to run 0 rebound for a couple of reasons. First off trying to duplicate 4 shocks with equal rebound is darn near impossible. If you do have rebound its pretty much works against the spring so how do you tune for that? I would rather tune for spring rate via the spring alone, and dampening via the oil. When your setting a shock with 0 rebound you really don't have to worry about shock length as the valve is plainly passing thru the oil and it really doesen't care where it is within the shock body as long as it has oil and no air.
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Old 11-23-2009, 09:24 PM   #4
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Quote:
Originally Posted by Johnny Wishbone View Post
I like to run 0 rebound for a couple of reasons. First off trying to duplicate 4 shocks with equal rebound is darn near impossible. If you do have rebound its pretty much works against the spring so how do you tune for that? I would rather tune for spring rate via the spring alone, and dampening via the oil. When your setting a shock with 0 rebound you really don't have to worry about shock length as the valve is plainly passing thru the oil and it really doesen't care where it is within the shock body as long as it has oil and no air.
How do you get the 0 rebound? once you bleed the shock its gonna have rebound to it. and with rebound when you have too much then are you makeing the tires take the load and do the work that the suspension is supposed to be doing
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Old 11-24-2009, 03:50 AM   #5
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My understanding of rebound is the more grip there is, the less rebound you need.

When there is grip on the track, your tyres need to have less traction.

Too much traction and too much rebound = too much rotation and in a worst case situation, grip roll.

Think of less rebound as a sponge in your suspension, for the front, it soaks up the steering sharpness. However, as with anything, you can have too much, or too little of it.

Car setup is all about finding a good balance of steering and grip. With too much grip the car can change direction too easily, and scrubs speed.

Too little grip and the car struggles to hit the apex's and pushes, costing time.
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Old 11-24-2009, 03:58 AM   #6
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You are never going to be able to reliably build a bladder shock with zero rebound. The bladder is always going to generate a degree of rebound. If you have zero rebound, you probably don't have enough oil in there and the shock is actually sucking the shaft in.

My advice is to build the shocks in a way you are comfortable with and that gets a consistent shock. To tune rebound, use different bladders or put o-rings/bushings inside them.
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Old 11-24-2009, 06:26 AM   #7
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Zero rebound meaning the shock shafts are fully extent outwards OR pushed fully inwards before fitting the shock caps back on?
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Old 11-24-2009, 06:35 AM   #8
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Originally Posted by wiscnitro View Post
How do you get the 0 rebound? once you bleed the shock its gonna have rebound to it. and with rebound when you have too much then are you makeing the tires take the load and do the work that the suspension is supposed to be doing
You can drill a 1mm hole in the top shock cap to release the air in between the bladder and the cap to get 0% rebound every time.
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Old 11-24-2009, 08:25 AM   #9
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Quote:
Originally Posted by Danny-b23 View Post
You can drill a 1mm hole in the top shock cap to release the air in between the bladder and the cap to get 0% rebound every time.
the Xray T3 shocks have that hole, as do the superior Tamiya shocks. It is quite easy to get zero rebound. However, one thing I am worried about is if you are approaching zero rebound, obviously you will have much less oil in the chamber. So if you have less oil, and push the remaining air out of the small hole in the shock cap, wouldn't this cause a vacuum in the chamber and actually case negative rebound (sucks the shaft back in)??

I've heard that some racers are loving zero rebound and sticking to it. The closest rebound I got with my AVID shocks is 25%. Technically, the shaft does not fully extend after being pressed down. The remaining length is controlled by the spring to extend the shaft.
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Old 11-24-2009, 08:43 AM   #10
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Quote:
Originally Posted by tc3team View Post

Too much traction and too much rebound = too much rotation and in a worst case situation, grip roll.
To me , too much grip doesn't exist . Too much grip/traction = wrong setup.

I agree with Mr Wishbone : rebound is for springs, oil for dampening. I don't see the point in adding a uncontrolled parameter, things are already complicated enough.

(hope this makes sense, english is not my mother language)
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Old 11-24-2009, 08:50 AM   #11
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Quote:
Originally Posted by heretic View Post
To me , too much grip doesn't exist . Too much grip/traction = wrong setup.

I agree with Mr Wishbone : rebound is for springs, oil for dampening. I don't see the point in adding a uncontrolled parameter, things are already complicated enough.

(hope this makes sense, english is not my mother language)
if your tyres are too soft, and the grip on the track is high, the sidewall of the tyre in effect, collapses under load, causing grip roll.

I guess you could argue that tyres are part of your setup though
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Old 11-24-2009, 09:01 AM   #12
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Originally Posted by tc3team View Post
if your tyres are too soft, and the grip on the track is high, the sidewall of the tyre in effect, collapses under load, causing grip roll.

I guess you could argue that tyres are part of your setup though
"Tires are part of the setup, but shouldn't be the major part. Tire traction wears during the course of qualifiers and mains. You want to dial the car independent of the tires as much as possible so the wear in tires does not affect your performance before you have to do a tire change."

Wise words told to me that I thought I would share.
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Old 11-24-2009, 09:28 AM   #13
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Quote:
Originally Posted by HarryN View Post
"Tires are part of the setup, but shouldn't be the major part. Tire traction wears during the course of qualifiers and mains. You want to dial the car independent of the tires as much as possible so the wear in tires does not affect your performance before you have to do a tire change."

Wise words told to me that I thought I would share.
Wise words? I'm not so sure.

Tyres are the most important part of the setup, the only part of the car that touches the ground.

Work on your setup to keep the car balanced throughout the day, I agree. But if you want to be fast, tyres are the major part of setup, no doubt about it.
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Old 11-24-2009, 10:14 AM   #14
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I do run full rebound but it is caculated into my geometry for my setup.
also your shock setup and your diffs are the most important part of your setup
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Old 11-24-2009, 10:25 AM   #15
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Quote:
Originally Posted by HarryN View Post
the Xray T3 shocks have that hole, as do the superior Tamiya shocks. It is quite easy to get zero rebound. However, one thing I am worried about is if you are approaching zero rebound, obviously you will have much less oil in the chamber. So if you have less oil, and push the remaining air out of the small hole in the shock cap, wouldn't this cause a vacuum in the chamber and actually case negative rebound (sucks the shaft back in)??

I've heard that some racers are loving zero rebound and sticking to it. The closest rebound I got with my AVID shocks is 25%. Technically, the shaft does not fully extend after being pressed down. The remaining length is controlled by the spring to extend the shaft.

Yup you're correct, it does cause negative rebound
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