My rear diff started slipping in and out of gear yesterday too, so i chucked a couple of washers in there behind the pin, too many and it was binding, took one out and it seems ok now ...
Yep, I finally got mine to be shimmed just perfect. I had the same issue. I somehow also broke a tooth off the ring gear. they mesh fine tho oddly. haven't had a chance to try it all under battery power yet, just turning it feels ok.
Well I am glad it has hopefully worked out for you, I gave mine a quick buzz up and down the driveway, but yet to fully test it.
I went from 20c hyperion packs to 40-80c Turnigys the other day. Need tyres now, mine are practically bald lol, still cant pop a wheelie
on demand, and forget about a flip haha. Trying to keep it straight is entertaining though.
Scrap what I said, it doesn't work and I now know why.
Take the shims out. The shims are moving the pinion AWAY from the pin. What is happening is because there is play in the pinion shaft/rear drivecup, the shaft backs out and the pin slips out the back of the pinion and looses
drive to the rear diff. The pin and the back of the pinion on mine are wearing because of this. that pin needs to be as far inside the pinion as possible so it doesn't slip out. Shims aren't the way to fix this (you should have seen what was left of the shim closest to the pin in my diff!).
It's very simple to fix and I should have thought of this before... While removing your shims unbolt the two big allen bolts on the back of your TVP's that hold your diff to the chassis. Remove the two bolts that hold on the esc.
Find/buy some of those little foam spacers that go in the drive cups for the front and rear dogbones and put one in each drive cup between the gearbox and the rear diff. OR what I used was Tamiya o-rings that are commonly used in their
oil filled shocks (and actually some of their drive cups). This will take up the play in between the gearbox and diff and stop the diff drivecup from backing out which in turn stops the pin inside the diff from slipping out of the pinion!
I just done this to mine, in hindsight I should have taken photo's to explain, but hopefully you get the jist of it.