3S/4S Diff Shimming (internal)?

[JSmalls87]

Has anyone also had issues with the internal gears of their 3s/4s cars stripping? I've gone through about 3 in my Kraton 4s, and it's just getting ridiculous. Lately I've only run the car on 3S thinking it would be gentler but nope. I'm running the Arrma metal diffs and input gears with the composite body. Also has happened to me running the HR diffs. It seems like the bottom metal diff outdrive, opposite the side of the ring gear always shifts up too much, which causes it to cram into one of the lower two diff planet gears. Then that outdrive loses teeth and causes the whole diff to seize up. See pic below.

I feel like this has to be user error on my end, or just a secret I'm not aware of, like internally shimming these diffs so there's no play and no chance of all the gears inside colliding with each other. I run the diffs with the gaskets, and shim the outside. I don't feel like theres much else to it that could be messed up. Once I rebuild each diff it works perfectly fine, its oly after about 3-4 runs that I notice the diff gears inside have been eaten all up.

Anyone else have this problem??

 

[Exc3l]

Never happened to me and I run 6s on metal diffs.

 

[JSmalls87]

Never happened to me and I run 6s on metal diffs.

on what car?

 

[jondilly1974]

Never happened to me either and I’ve ran up to 8S on a Typhon 3S.

 

[JSmalls87]

So now I’m really clueless as to why the heck this keeps happening to me.
What driveshafts were you all using? I wonder if mine have too much play in them and when I hit the throttle while in the middle of a turn they jolt the gears too much

 

[jondilly1974]

So now I’m really clueless as to why the heck this keeps happening to me.
What driveshafts were you all using? I wonder if mine have too much play in them and when I hit the throttle while in the middle of a turn they jolt the gears too much

I was using stock driveshafts at the time but they barely held up for one pass. Ended up buying the CVDs instead. Only made a few passes on them. I ended up giving up on the 3S platform to dedicate more time to my Mojave speed run build.

 

[GRC]

I did notice small nicks in some internal gears once, but I replaced them before it got any worse. Nothing like what's in your photo. Is the bearing inside the diff running smoothly? The rubber O-rings are OK? What weight oil are you using?

 

[GilMKIII]

What kind of driving do you do?

 

[Warby]

first I've seen those gear do that
Check if one of the wheels is tight to turn. look for a seized wheel bearing or something. That's when those gears will be working hard. If one wheel is spinning faster than the other side or one wheel stops hard while the other is spinning or a transfer of drive from one to the other.

 

[JSmalls87]

What kind of driving do you do?

Nothing too crazy honestly, just bashing around in my backyard. Like I said this has even happened running strictly on 3S

first I've seen those gear do that
Check if one of the wheels is tight to turn. look for a seized wheel bearing or something. That's when those gears will be working hard. If one wheel is spinning faster than the other side or one wheel stops hard while the other is spinning or a transfer of drive from one to the other.

Everything is running smoothly....I switched out my axles to the Arrma ones. I was using GPMs and I've been fine the past two runs. I check that the diff is still working properly every 3 min or so now though. Maybe that was my problem, I really hope so. I hate when this stuff happens especially since no one knows why lol