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Old 11-24-2009, 11:27 AM   #16
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Originally Posted by Nick Priest View Post
Yup you're correct, it does cause negative rebound
So to eliminate negative rebound, you need that air in there, while maintaining zero rebound. Now here is the next question, wouldn't this cause a dead-spot in the dampening? Meaning, since there is so much air in the chamber, and the car makes a turn hard enough (depending on how much oil is in the chamber in comparison ) wouldn't that cause the car to jerk in the opposite direction of the turn? Could this cause too much roll and flip the car over?

Depending on what the answer is, I think gas or air filled shocks, like real cars, may be the better way to go. If you want less rebound, let some air out. If you want more rebound, let some air in. But you would not get negative rebound or have a dead spot like liquid filled shocks.

Just my assumptions here. I am looking for a more clear understanding how R/C shocks work.
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Old 11-24-2009, 11:36 AM   #17
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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
no, I wasn't thinking about tires as a setup parameter given the fact that we all run handout ( rubber) tires nowadays...At least I hope for you !

I had not thought of the case you mention but I guess that to get an effect such as the one you describe, you would need high sidewall, very soft rubber and very little camber. The edges of rubber tires are rounded enough, generally, and if I still get grip roll, then a layer of CA on the outer edge works awesome ( for me, at least).
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Old 11-24-2009, 12:18 PM   #18
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So to eliminate negative rebound, you need that air in there, while maintaining zero rebound. Now here is the next question, wouldn't this cause a dead-spot in the dampening? Meaning, since there is so much air in the chamber, and the car makes a turn hard enough (depending on how much oil is in the chamber in comparison ) wouldn't that cause the car to jerk in the opposite direction of the turn? Could this cause too much roll and flip the car over?

Depending on what the answer is, I think gas or air filled shocks, like real cars, may be the better way to go. If you want less rebound, let some air out. If you want more rebound, let some air in. But you would not get negative rebound or have a dead spot like liquid filled shocks.

Just my assumptions here. I am looking for a more clear understanding how R/C shocks work.
I like that Idea just run them as a "gas" shock. I would think a Air/gas shock would be more consistant them having 4 equal shocks fill with oil. Or maby it could back fire only one way to find out
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Old 11-24-2009, 01:00 PM   #19
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I like that Idea just run them as a "gas" shock. I would think a Air/gas shock would be more consistant them having 4 equal shocks fill with oil. Or maby it could back fire only one way to find out
Well as the saying goes in the real racing world; "the racer with the better suspension owns the track."

Gas filled shocks would definitely be more consistent. As far as backfiring, if we go with how shocks are currently built, the o-rings could leak, a hard crash could cause the cap to pop off, and a whole myriad of other things.

But you're right, only one way to find out.
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Old 11-24-2009, 01:19 PM   #20
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I like that Idea just run them as a "gas" shock. I would think a Air/gas shock would be more consistant them having 4 equal shocks fill with oil.
The major problem with attempting an air or gas shock for RC is that the air volume is so small it would be next to impossible to make small pressure changes, and any air leakage would basically kill that shock. If you could have very good seals and a remote reservoir you might be able to do it.
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Old 11-24-2009, 01:31 PM   #21
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I thought I rember seeing a tool that will measure your shocks 2 at a time and make it equal when you fill them. I don't rember who mde it or even were I seen it but I know its there
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Old 11-24-2009, 01:52 PM   #22
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I thought I rember seeing a tool that will measure your shocks 2 at a time and make it equal when you fill them. I don't rember who mde it or even were I seen it but I know its there
I have that tool. It works quite well!

Just make sure the top slider (where the top of the shocks connect to) is as loose as it can be. It is quite resistance and can skew the rebound of the shocks. Other than that, I enjoyed it. But it works for people who want rebound in their shocks. I think some people and most racers are aiming for zero to 10% rebound. Some very low number where the shock is doing its job of dampening and the springs are doing their job as rebound.
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Old 11-24-2009, 02:30 PM   #23
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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.
Actually the fill and hold level of the oil is the same if not more than when your doing a bleed type rebound setup. The other thing to remember is there will be no oil on the top side of the blader, which is keeping the oil in the lower portion of the shock body, the only air that is going to come out the top is if you have a very weak blader (no pun) that balloons out when the shaft/valve is moved up and down within the shock. (The hole in the top lets the top part of the shock equalize.)If that is the case its time to change out that blader as its a weak piece to begin with and will cause you issues with which ever system you prefer to run, although I believe you would pick up on it faster with a 0 rebound shock as it would feel very "dead". Now some people also control the rebound with the foam on the top of the bladder, again used to limit how much the blader makes the shock rebound, but most setups I see eliminates the foam. The 0 rebound shock makes the car feel less bouncy or planted better. It also seems to make valve hole changes more noticable or the feel actually feels different.
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Old 11-24-2009, 05:05 PM   #24
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Across the board most setups are going to zero rebound. I think that it calms the car down on high traction. Most of the time I see rebound is on asphalt setups to get the car to square up more.
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Old 11-25-2009, 03:56 AM   #25
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no, I wasn't thinking about tires as a setup parameter given the fact that we all run handout ( rubber) tires nowadays...At least I hope for you !

I had not thought of the case you mention but I guess that to get an effect such as the one you describe, you would need high sidewall, very soft rubber and very little camber. The edges of rubber tires are rounded enough, generally, and if I still get grip roll, then a layer of CA on the outer edge works awesome ( for me, at least).
As tyres heat, the sidewall will flex more. This is more apparent on softer compound tyres, especially the cs22. You can experience grip roll in such situation, or the back end of the car can step out, depending on your car setup.

Our track is quite small, so the car is doing a lot of steering in an 8 second lap.

If you had full rebound, you would probably experience grip roll where I race with the above tyres...

I race at one club who still use foam tyres, but if you choose to you can also use rubber tyres - but the foams are always faster when

1) you have the right compound and,

2) the car is set up correctly.

No one in the A final will use rubber tyres for this reason. I have tried to find a setup, as have others, but they just dont work as well, with or without tyre warmers.
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Old 11-30-2009, 08:33 AM   #26
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I thought I rember seeing a tool that will measure your shocks 2 at a time and make it equal when you fill them. I don't rember who mde it or even were I seen it but I know its there
probably not what you're talking about, but it could be useful:

http://www.losi.com/Products/Feature...odId=LOSA99170
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Old 11-30-2009, 09:46 AM   #27
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I like to call 0 rebound " dead shocks".
I can tell more of a difference in offroad with building your shocks with rebound or dead. The dead shock build seems to make the buggy jump more shallow and roll threw the bumps. Buggy shocks built with rebound jumps a bit higher and seems to feel it rolls over bumps verses rolling threw the bumps.
As for onroad goes. I would like to think the car would be a bit more responsive with shocks with some rebound. I would not think anyone would never want full rebound for onroad. I always run some rebound but I am always trying to find a more reactive car.
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Old 11-30-2009, 09:58 AM   #28
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probably not what you're talking about, but it could be useful:

http://www.losi.com/Products/Feature...odId=LOSA99170
Yup thats it
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Old 11-30-2009, 02:23 PM   #29
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you need to think of rebound in terms of the shocks installed length at ride height. Because we only have single adjustment shocks in RC there's only 3 possible combinations.

Assuming you have a perfectly airtight sealed shock then a rebound setting less than the installed height will assist the spring in bump and resist it on rebound. If your rebound is greater than installed height, then it will resist in bump and assist in rebound. Two different effects. The last setup is when your rebound is within the shocks operating range eg. if your rebound setting was exactly the shocks installed length it would resist in both bump and rebound.

What would be cool is if someone developed shocks that were independently adjustable in bump and rebound rates. Some kind of simple ball valve setup might be possible.
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Old 11-30-2009, 02:30 PM   #30
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you need to think of rebound in terms of the shocks installed length at ride height. Because we only have single adjustment shocks in RC there's only 3 possible combinations.

Assuming you have a perfectly airtight sealed shock then a rebound setting less than the installed height will assist the spring in bump and resist it on rebound. If your rebound is greater than installed height, then it will resist in bump and assist in rebound. Two different effects. The last setup is when your rebound is within the shocks operating range eg. if your rebound setting was exactly the shocks installed length it would resist in both bump and rebound.

What would be cool is if someone developed shocks that were independently adjustable in bump and rebound rates. Some kind of simple ball valve setup might be possible.
Ask and you shal recieve http://www.teamxray.com/teamxray/pro...k%20Absorbers\

is that what your looking for?
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