How do you biuld your TRF shocks?

[Netmav]

Hi guys,

I'm having some trouble getting my TRF HL shocks completely sealed. I always get some "sweating" around the rod at the bottom of the shock body.

I've tried to build my shocks with the standard Tamiya O-rings (red), Tamiya Competition O-rings (blue) and the Tamiya X-rings.
I've got three set of these shocks, but I cannot get any of them to stay completely sealed?
I use Green Slime on the O-rings when I build them.

Anybody got any tips on how to make them 100% sealed?
Or does this happen to all Tamiya TRF shocks?

Thanks.


\Martin

[sosidge]

Are you trying to completely fill the shock with oil? Because that won't work, they need some air in them, and excess oil will just get forced out of the seals.

I always built them like an Associated shock - piston down, oil to the brim but with a concave surface, screw the oiled cap on, check for even damping throughout the stroke with no more than a tiny squeak of air. I've never managed to get the bleed screws to give me the kind of shock I like.

[MHeadling]

Sorry to crash the thread, but anyone know the part number the for the o ring for the shock cap?? The one that goes around the shock body??

Maybe try the Nortech whitie o rings? available from JT models...

[Netmav]

I've always used the "Shock building guide" on trfracing.co.uk, thinking that was the best solution.
http://www.trfracing.co.uk/page_1265187551237.html (scroll down a bit)

Maybe I should mention that my shocks works and feels perfect, except for the sweating.


\Martin

[sosidge]

Originally Posted by Netmav

I've always used the "Shock building guide" on trfracing.co.uk, thinking that was the best solution.
http://www.trfracing.co.uk/page_1265187551237.html (scroll down a bit)

Maybe I should mention that my shocks works and feels perfect, except for the sweating.


\Martin

Well, that is pretty much the opposite of the way I build my shocks, it builds a shock that has no air in it but which will suck the damper shaft back in when extended, the way I do it builds a shock that will allow the damper to rebound. But everyone has their own way, and that way is successful for a lot of people.

A little "sweating" is tolerable, most of my shocks sweat a little over a period of a couple of months. If the shock is unusable after resting for a week then that is not good.

[MHeadling]

I have found the O rings for the shock cap:

BE13- 9444361

Any ideas where I can get these??

[Netmav]

Can you let me know how you build yours in detail?
I have to do a rebuild after 4-5 meetings on mine..

Originally Posted by sosidge

Well, that is pretty much the opposite of the way I build my shocks, it builds a shock that has no air in it but which will suck the damper shaft back in when extended, the way I do it builds a shock that will allow the damper to rebound. But everyone has their own way, and that way is successful for a lot of people.

A little "sweating" is tolerable, most of my shocks sweat a little over a period of a couple of months. If the shock is unusable after resting for a week then that is not good.

[Netmav]

Try searing for that part number at www.vellrip.com
Slow site, but quick service!

Originally Posted by MHeadling

I have found the O rings for the shock cap:

BE13- 9444361

Any ideas where I can get these??

[Airfixie]

Hi sorry but my brother pretty switched on,you 100% sure theres no air inside

[MHeadling]

Thanks Netnav, is the service from Vellrip good??

[Netmav]

I've got nothing but good things to say about their service.
I've bought from them a few times, and never had any problems.
Shipping's quite quick as well.

They might not be the cheapest, but they've got a lot of "hard to get" items.

Originally Posted by MHeadling

Thanks Netnav, is the service from Vellrip good??

[sosidge]

Originally Posted by Netmav

Can you let me know how you build yours in detail?
I have to do a rebuild after 4-5 meetings on mine..

Pretty much as I wrote earlier..

- Pistons down in the shocks
- Fill them to the brim but with a concave surface (stroke up and down a few times to get the big air bubble out and top-up again if necessary)
- Moisten shock cap with oil
- Screw on shock cap
- Test the shock by moving it through its full stroke. Damping should feel even through whole stroke. There might be a tiny squeak of air at the top of the stroke.
- When shock is fully extended the shaft should not pull itself in. When the shock is full compressed the shaft may rebound a small amount.
- If the damper feels stiffer at the top of the stroke - there is too much oil. Remove the cap, remove a little oil, refit. I don't use the bleed screws because I find it hard to get a consistent balance of oil and air through them.
- If the damper has a large air squeak at the top and the piston feels undamped (going wholly into air rather than oil), then you need more oil.

Why do you need air in the shocks? Because you need to compensate for the volume of the shock shaft as it goes into the shock body under compression. The damper oil should be treated as incompressible, whereas air is easily compressible.

Most other classes use a bladder instead of aeration but, partly because 10th cars are so light and softly sprung (and partly because the most successful cars have always run aeration shocks ), a bladder adds a bit more springy-ness to the shock which makes it feel worse over the bumps, whereas an aeration shock is a bit more "dead" over the bumps.

Hope this helps - it's just my approach though.

PS 4-5 meetings is not so bad, especially if you are running in dirty conditions which will deteriorate the shock o-rings faster. I doubt you are doing anything wrong as it is.

[Netmav]

Thanks Sosidge!
I'll give this a try when I rebuild my shocks tonight.

I feel 4 or 5 meetings per rebuild is not enough, as we run on a small, tight carpet track. And I saw the shocks on my frieds Schumacher CAT SX3 at the last meeting: approx. 15 meetings, and still 100% dry/sweat free! I almost bought a set of Schumacher Big Bores just because of that, but then I remembered that they are of the wrong colour!!

[Jan Larsen]

If sosidge's method fails, try this:

- pull piston up about 5mm from bottom and let it stay there
- add oil to brim
- pull piston up just before it exits the oil
- pull it back down again slowly and see the air underneath the piston being forced up and oil forced down.
- pull the shaft to the very bottom and fill rest of the shock body with oil
- let the last few bubbles escape (takes a few minutes)
- screw cap on WITHOUT the bleeder screw in
- pull piston up again all the way. Oil must come out the bleeder hole near the top of the stroke. While keeping the piston at the top, screw bleeder screw in.
- Clean
- Job done.

The advantage with this method is that you get equal amount of oil in the dampers and no rebound. Every time. I have the shock eyelet adjusted so the piston cant escape the oil, even at the very top of its stroke.
I've used this for many years and the car lands even the silliest of jumps.

[Netmav]

Thanks for the tip, Jan!

How does this method hold up against leaking/sweating at the bottom of the shock? How often do you need to rebuild when you do it like this?


\Martin

Originally Posted by Jan Larsen

If sosidge's method fails, try this:

- pull piston up about 5mm from bottom and let it stay there
- add oil to brim
- pull piston up just before it exits the oil
- pull it back down again slowly and see the air underneath the piston being forced up and oil forced down.
- pull the shaft to the very bottom and fill rest of the shock body with oil
- let the last few bubbles escape (takes a few minutes)
- screw cap on WITHOUT the bleeder screw in
- pull piston up again all the way. Oil must come out the bleeder hole near the top of the stroke. While keeping the piston at the top, screw bleeder screw in.
- Clean
- Job done.

The advantage with this method is that you get equal amount of oil in the dampers and no rebound. Every time. I have the shock eyelet adjusted so the piston cant escape the oil, even at the very top of its stroke.
I've used this for many years and the car lands even the silliest of jumps.

[MikePimlott]

I soaked the o-rings in some oil over night and then when building them i added 2 extra shims to each cartridge.

This stopped mine from leaking.

[Jan Larsen]

I have no problems with leaking and never have had when using the standard red o-rings. The blue competition ones however I had nothing but trouble with. I ended up adding a bunch of shims to the cartridge to stop them leaking but that just made them feel like the red ones, so I threw them away in anger and have never used them since.

[Netmav]

Btw, has anybody else tried the X-rings from Tamiya (#42214), instead of O-rings, in their shocks?

[Rich D]

Yeah I'm running the xrings silicone shock oil version. The fronts went in and didn't weep oil until I ran the car. Had to shim the rears to stop them leaking even when the car was just sat on the shelf in my workshop. After shimming the car sat for a week and no sign of oil. Ran once with them fitted and they have weeped quite badly. Not ideal but they do feel so much nicer than the std orings. I don't mind rebuilding my shocks after every meeting if they work well. My 2WD Kyosho velvet shocks feel just as good yet don't weep at all which is annoying.

[Netmav]

Thanks Rich,
That's pretty much exactly how I would describe my experience with them as well!
But I do mind rebuilding them after every meeting, though.. I just don't have the time for it..

I really do want to stick with Tamiya shocks, as I have a lot of spare parts for them.. But for that I need to make them hold up better..
What to do, what to do..