YZ2 front shock mystery
 

I have a mini-mystery going on with my DT, where i need to have front shock attached to the outer most hole on shock tower and inner most hole on the suspension arm, in order to get some sort of decent working of the shock. Any other combination sees the shock have a dead effect where it has hardly any rebound. Some might say it's the shock, but I have put the shocks from my CA - which work absolutely fine on the CA - onto the DT, and the same result happens, a shock that is acting dead. I've rebuilt the DT shock from scratch too, with new pistons/o-rings/oil etc, and that hasn't solved it. The other point to note is that if i tighten up the nut holding the shock to the tower i lose around 1.5mm of rebound, so that is not even as tight as you would normally expect to be able to have it. Any thoughts on what might be going on? thanks

Hi,


Is the car the same with the CA shock on the DT and the DT shocks on the DT?


Have you tried the DT shocks on the CA?



Does the arm move freely with no shock on it?


Is there any chance the spring cup is fouling on the arm?
Trapping and causing friction.




MiCk B. :-)

Yeah. With the shock off the car it operates perfectly normal. It’s as if the car itself has an issue and doesn’t matter what shock is put on it. And to make doubly sure the shock isn’t getting fouled by the tower I put a small spacer on the screws the top of the shocks fit onto, just to give it a few more mils of clearance.
And the arms move freely with no shocks on too.

Do you have to pull down on the arm to get the shock to fully extend?

it sounds like you are over-tightening the nut holding the top of the shock, which is compressing the plastic shock perch into the shock cap.

Swap the plastic shock perches for the alloy ones, or replace the plastic perches and don't over tighten - ensure the shock moves freely on then. :thumbsup:

Are the screws in perfectly straight?
If they are in cockeyed it can things bind up depending on the design of the mounts top and bottom.

With the shock off the car it fully extends as you would expect with decent spring. On the car it won’t fully extend as it rebounds. By like 50% it only goes, thus the dead type condition. But if I move the shock to the holes noted above, I get all but say 4-5mm of extension. Screws are on straight - replaced them to eliminate that possibility.
Re the perches (Neal) , these are at the bottom of the shock, not near the caps. Did you mean the shock cap ball? It definitely though does make a diff by not over tightening the nut - but to the extent where I am only tightening them up finger tight, which doesn’t fill me with confidence!

If you have over tightened at the shock caps previously, you will need to replace the plastic mounts as you will have warped them by compressing them with the nut.

ok - we may have made some progress! I have swapped the alloy shock cap balls that were on my CA, and put onto the DT which had the original plastic variant - as on examination it appears indeed there was no free movement for the shock cap. Now there is (one of the plastic shock cap balls was infact stuck inside the shock cap too). Question then is now, what is the part number of the alloy version? (the ones i have came with the CA I bought off another chap)
Is it YS-8BH? As I will need a new pair of them to replace the stuffed plastic ones.
Thanks for guidance on this. .Much appreciated..

yes its: YS-8BH - YOKOMO ALUMINIUM SHOCK CAP BALL (HARD COAT)
https://www.rccarshop.co.uk/spares/y...-hard-coated-p

They come in a pack of 4. its an odd part number as its a older yokomo part/number.

I run alloy perches with plastic caps, and plastic with the alloy caps. sounds like your plastic ones will be a bit squashed now, but may be fine with the alloy caps.

This part should be standard on the yokomo kits, it used to be on the bmax range.

I've seen this issue before, but glad you have got it sorted.

The screws holding the shock caps at the mount plate bend pretty easily. I've replaced several pairs.

The bend can be sufficient to have the collar fouling against the plate.