You may not be able to hear it on-power or at WOT due to engine noise, but most likely it is skipping as well. It's most noticeable off power because the brakes are applied, stopping the center-rear shaft and thus the rear Pinion gear. Yet, the rear tires are still rotating, putting more pressure on the rear diff to spin. This causes the diff teeth to skip across the pinion teeth, and the "click" you're hearing. It's more likely to happen on a truggy, due to the larger rear tires - more rotating weight forcing the diff to turn while the brakes and pinion are stopped.

I've told most people that once the ring/pinion wear down to a point where there is no more (black or gold) coating on the teeth, it's best to replace the gears. You can ride it out, but it's just going to cause more problems down the road. However, the rear case and plastic inserts can wear just as easily. As long as you monitor the "click" and shim the rear diff over towards the pinion, and close that gap, you're fine for a few weeks. After a while though, it's best to swap out those gears - and it won't hurt to do the rear case beacuse of the chance of plastic altering slightly due to the possibility of frozen bearings, general wear and tear, worn inserts, etc etc.

great explanation...thank you very much!....that makes perfect sense....

I bought a new diff out of a roller off ebay. When I got it, I took it apart to check fluid level, gear mesh and backlash. This thing was brand new and by the time I was done shimming , it had 1 skinny shim on the pinion side. After some more wear, I'll have to lose the shim and then there will be none on that side. I don't think I'm gonna get much run time out of this new diff. Any thoughts or similar experiences?

Yeah I would also like to know if guys get down to one of the thin shims on the pinion side or even none, and if so how long they run like this. I lost a rear diff sunday night that was shimmed tight with one high spot, and this was with a thin shim on pinion side. Probably got a couple gallons out of it

I forgot to ask you about it. Did you start with 1 skinny on the pinion side or did it slowly wear and you kept taking out shims to that point.

When the ring an pinion were new I had 2 thin and 1 reg on pinion side. And then gradualy took away shims on the pinion side. Of course every diff is different and wont be shimmed the same.

That's about right for a starting point. You kept a good eye on it. That sucks it was only 2 gallons though. I'm going to rethink this whole diff problem a bit.

Someone needs to come up with a 3rd bearing for these to ride on, an all aluminum case or better plastic. Something different than what we're doing.

It's called the muffler bearing boys. You gotta get one.

Ok thinking out of the box, so no flamin'. Some sort of case stiffener. Either an outside wrap or another insert like 2 aluminum plates built into the aluminum outdrive inserts we all run. Wish I still had access to a machine shop.

Hahaha! Franko what's up! You ready for Saturday? I'm bringing Pop Rocks and 7-up.

It's called a Mugen

And ohh ya I'm ready. I need something special you guys got some time on the little track. Gotta shim my diff too hahaha it clicks a little. Man I knew you were kaya. Pop rocks and 7up I'm telling...

Hahaha. I'm not Kaya. LMAO. That was a funny conversation though.

I guess I have been fortunate because I have 7 gallons on my truck with the same ring and pinion. I did replace the rear gearbox at about 5 gallons though.

Oh too funny, Ive seen some 6 diffs let go Just as bad as some Losi's have....Oh and lets not mention the "other" part Mugens can hang onto for very long.


On a side note, I honestly dont want to think of how many gallons i have on my Truggy ring and pinion's.....Its well over 15, with periodically checking how thing's feel. After the NC and checking thing's out I think i have 1 tooth on the Ring that's taken a hit...The rest of the gear's look Great.