play in shock seals

[Juddy]

I have found that my shocks are gaining rebound after a couple of runs after bleeding. I've heard about this issue and apparently shimming the play out between the o-ring and plastic spacers is the solution? has any one tried this and did it work?
If so what did you use? I was thinking of trying to get some of the old nylon shims we used to use to shim the old brushless motors? Does anyone know if these are available, or have a better solution?

Thanks

[janus_77]

from RCtech:

Janus

Ok, I'm going to restart the shocks discussion a bit.

Like most of you know, the shocks have a fair bit of sideways movement between the shaft and the shock housing.

Problem is that in testing it was found (mainly by Nik Weyers) that air gets in this way no matter which caps (alu/plastic) you run. We tested a number of different o-ring types ( original, low friction, aftermarket 801's 70sh ), but the problem remains.

I have some custom shaft guides in mine ( the guide ring between the o-rings made to much closer tolerances), which helps a lot (!). But not everyone has access to a lathe.

Not sure if it's a batch issue or more widespread, since the cars that were tested were all bought around the same time. So there probably all from the same batch.

Do any of you have, or had this issue ? and more importantly is there an actual solution ?

Janus

Not sure if we have a solution, but its a "work-around" anyway

Just add thin shims (I used 0,3mm) to the o-ring cartridge to put more pressure on the o-rings. This enables the O-rings to support the shaft better. Just add untill you notice the shaft has added friction when moving.
Its not really a job they're meant to do, so rebuilds will become more common I guess. But it does help. Now after 2 runs the shock has added a little rebound but nothing as silly we saw at the MIO track

Hope this info helps....

Sitting Duck

I have found a solution for the shocks that build rebound.

At first i thought it was the bleeding screw, so i put some o-rings on the bleeding screw but the problem stayed.

Then i thought is was the side play of the shock shaft. I replaced the big flat collar with another one from TLR. It is 3x7x1 mm and i think it is used as a ballstud spacer.
Replacing the collar was better but didn't solve the problem.

Then i tried some robitronic P3 o-rings and now my shocks are ok. I think the robitronics are the same as the kyosho p3 o-rings but i am not sure. Next i am going to try kyosho grooved o-rings because the robitronics seem to have a lot of friction.

Skrichter

Shocks - I'm not sure if the clear orings have been updated, but I COULD NOT BELIEVE the amount of friction/sticktion. My AE (and TLR) vehicles don't have anything close to this amount of friction. I replaced the stockers with AE orings (since they both use a 3mm shaft). To combat the air suction that everyone is reporting, I added a .3mm shim (which was suggested somewhere in this thread). Shocks are good now (almost too free) -- I can bleed my shocks with ZERO rebound with no problems now.

[neallewis]

I rebuilt my shocks last week and they have had one indoor meeting run. I replaced all the seals completely with fresh ones. I've just removed them and both were pressurised, one a bit more than the other. I'm running yok blue o-rings. I've re-bled and have placed a two 4x6x0.15mm shims in each of the bottoms to press the plastics into the orings.

I'm running friday night and will check them afterwards to see how they go.

[OneKiwi]

Mine are similar with building pressure. I also bleed/air them after a couple of runs. I do notice that if I have a little less oil in the shock from leaking they don't be as pressurised
Where did you get the shims?

[janus_77]

Originally Posted by OneKiwi

Where did you get the shims?

KYO96642
TDR709010

[MiCk B.]

I've had similar running the AE bigbores.

(Product Plug)

This is what I've been using in mine to 'pack' the o-rings.
Teflon shims.



I have them in 0.010 and 0.015.

MiCk B. :-)