XRAY - Model racing cars

I have the new 810 with the 3 bearing diff pinions and am having no end of trouble with the gear mesh in these damn things.
The old 2 bearing setup diffs are easy and have good mesh and run smooth with no noise, but this new 3 bearing setup has problems.

IF you are able to get good lash, the mesh is still bad and grindy and noisy when the car is being driven and the drive train has a fair bit of friction.
To get even a slight amount of lash you need to shimm the crown wheel away from the pinion which is very odd for xray too!
This leads to the next problem which is when you put the two .1 mm shimms under one bearing for the diff, the bearing sticks out to far and the out drive rubs on the bearing inner. Which is probably the readon why guys have leaking diffs, because the outdrive pulls really tight against the thrust washer and the oring inside the diffs. This isn't a problem if you use the old 8x14x4 bearings, but with the 8x16x5 bearing, the inner race is 1mm thicker and the outdrive hits on the bearing. FIGURE that one out !!!!!! This leads to more rubbing and so forth.

It seems the pinion gear machining is wrong or the diff casing machining is not right for the new diff setup.

Is this a problem with all the 3 bearing diffs ?

What is going to happen about the out drives hitting on the bearings if shimms are used ?

Ive had xray for a long time, and this one is perfect, EXCEPT for THE DIFF GEAR MESH !!!!!

viewtopic.php?f=9&t=10476 this thread was also running with a similar issue. The 3 bearing version i had was prototype & it does shim different but only in not as many shims, i will build up a new one to see whats happening .

Thanks Bren, This little problem has got me a bit bewildered. I will have a little bit closer look too and check the pinion depth in the casing and to the crown gear. I believe the pinion is too deep and too close to the crown wheel and is not meshing to the crown wheel properly even is you have lash. Pinion needs to move back more away from crown wheel and then we can close up the mesh again and all should be good. BUT, its not that easy to just move the pinion deeper

After building many older pinion style car and some with the 3 bearings pinion, i can defentily say that there is a problem with the meshing being too tight. even more weird is that some tighter than other. however the real problem is that you cant always solve this with the kit shims, because if you use too many it pulls the outdrive too much.

The solution is kyosho shims, they have the bearing outer diameter (16 mm), and they sit between the bearing and the bulkhead.

Dotan is right on. Don't shim betwen the out drives and bearing to move the diff over. That'll stress the inside of the diff.

Shim between the outside of the diff bearing and bulkhead. I used one shim tighter on the front of my 809 and it worked well.

I just happened to have a shim rolling around my pitbox. Anyone have a part # for that Kyosho shim?

Search under SHIMS on a-main. This is the kyosho shims but like I said search & you'll find different sizes I have .1 & .2 in my box some are ofna & some are mugen these koyosho ones are .15.
http://www.amainhobbies.com/product_inf ... l-Shim-Set

Hi I have another problem with an active Diff with the 43T gear.
This time the gear mesh is not to tight, it is too big.
I cannot intall enough shims to get the gear mesh tight enough. I installed the maximum number of shims possible, but the diff is still "clicking over" under hard breaking.
There is no problem with the standard diff, only the active diff.

Somebody any ideas?

THX MArkus

Are u sure u didn't accidentally build the active diff with the ring gear from your old diff? The gear that comes with the active diff is thicker as the active diff sit differently.

I'm sure some one can chime in on the ring gear dimensions. Maybe your AD came with the open diff gear?

Yes I`m quite sure that it is the right gear, because I got the AD with gear so I do not have to change the gears.
But the AD is is not new, but all the teeths of the gear look fine.
But I will compare the two gears if there is a difference. I had the AD in my XB8R where it worked fine.

But by the way, I used my old active diff and changed the outdrives and the crown gear, but maybe there is a difference in the diff housing of the old AD for the XB8 and that one for the 808? Could this cause this problems?

THX Markus

I used the mugen, associated style shims in my diff to get the lash right, but the gear mash is still noisy and not right.
its ok if you just push the car on the ground, noisy but smooth. Lift the car off the ground and turn with the front or rear tyres and you get the god awful feeling of incorrect meshed gears. I remove the motor when I do this test to get rid of the noise from the clutch bell.
The more you load the gears up, the worse the problem becomes. In "real cars" we change the pinion depth to recify this problem.