Stripping Diffs

[Jhsmith1987]

this is my first time to strip my rear diff, after only my 4th run with the mmp 5700 and the rear diff is completely stripped, the front bulkhead is alum, and i shimmed it when i got it, but havent shimmed the rear, because i just havent had to open it up yet.
but when i opened the front i noticed something that no one here seemed to know about at the time, a shim
on the input gear. here is a pic:

that shim the inside hole was drilled out a little by me before i got the shims i needed to put on the ring gear, so imagine that shim with a smaller inside diameter.

now that i am going to get into my rear bulkhead and replace diff, i know it is time to shim, but my question is since i am shimming the ring gear should i shim the input gear as well?
also is stripping diffs very common with a bb set up?

[jimbo74]

stripping the diffs is very common with a big block setup

[Jhsmith1987]

ok, i figured it would be.. so what do you think about the input gear shim?

[jimbo74]

did you put that shim there?


that almost looks liek it might be a dust cover from a bearing

[Jhsmith1987]

no, it come stock that way only with the inside hole smaller, because before i ordered my shims, i drilled it out so it would fit the ring side, but, the rear one hasnt been touched. so should i leave it?
have you ever hear of putting shims on the input, would there be any reason to shim it, if you shim the ring?

[CMD-J]

For alloy bulks: yeah i would shim the input gear too. You'll need one less shim on the ring gear if you do it on the input gear.
I used a Tamiya 4x0.2 shim. HR part-no. W4X should work too.

For plastic bulks: I'm not sure. Have not tried it yet. The shim would sit against the housing and might scrub and work themself in.

(The washer on the above pic by Jhsmith looks rather big to me. Shouldnt be a shim sit tight on the shaft? Maybe its some sort of seal, as Jimbo suggested?)
=>Edit: didnt read you bored it out.

I did it like this: (not my pic, hope its ok to post it)


Rondelle is french for shim.

[Jhsmith1987]

like i said the shim in the pic above was drilled out by me to put on the gear side, as suggested before when i asked if this was normal cause it come stock on the merv..

[jimbo74]

stock doesnt have a shim, not quite sure what you are talking about drilling it out for the gear.....

[Jhsmith1987]

I'm telling u out of the brand new box first time I opened the bulkhead, I seen that little shim on the input gear, except the inside diameter was a lot smaller cause i bored out the shim to fit on the ring side. When I open the back bulkhead I'll take a pic and post it, but I swear to u it is there from the factory at least mine was

[Ghostbuster]

stripping the diffs is very common with a big block setup

Makes me sad and I haven't even ran my BB yet

[50togo]

Forget the shim buy a few 7079's and some associated 21141 and you will be set!

[Jhsmith1987]

Yea I got a few left from my last stripped diff

[50togo]

i would do my break in procedure might help you out!

[Jhsmith1987]

Yea I read that, I am going to try that out...

[pooochie]

stock doesnt have a shim, not quite sure what you are talking about drilling it out for the gear.....

The new stock DOES have a shim.

[devildog88]

...and it doesn't help apparently go figure!

[ArmySSG]

So this may b my only down fall.. 50 ima just have to mail u a set of alum bulkheads front and rear and just pay u to shim my diffs for me... Sounds way too complicated for me lol...

[50togo]

All that talent you have! Once you do it you will.be a pro

[Jhsmith1987]

Army.. It's super easy man jut let us know when u get your shims, we will walk u through it 50 walked me through it, the whole time I was doing it I was between here and a Alan wrench gettin coached the whole way.. Realized its way easier than u may think

[Jhsmith1987]

maybe i didnt strip the diff.. i know i broke the center drive shaft but now that i have the diff out, it looks fine.. dont looke stripped at all.
4 chipped teeth on the ring but it should be fine until my new diff comes in if i shim good right?

[50togo]

How bad is it chipped ? Shimmed with a stocker maybe but a bb don't know!

[Jhsmith1987]

actually i just found a new ring gear i didnt know i had.. just no new pinion. but i dont see any chips in this one..
o and here is a pic of the shim on the pinion gear that come stock on it.

[Dadx2mj]

That "shim" looks a lot like a shield from a bearing. You sure the bearings are all intact or that is not left over from an old bearing you replaced?

[Jhsmith1987]

No it came out the box like that. I seen it in the front bulkhead when I stripped my first diff. I've never even had the rear diff apart untill now.

[QR-1fan101]

My motor is making a klunking noise when I take off slowly is that bad FYI mini e revo vxl

[50togo]

It may have a stripped diff. Not too uncommon. You may need Traxxas 7079 and associated 21141 shims

[SiNiST3R]

I stripped 2 rear diffs in a week. Third time around, I installed it free, but as tight as it can be while stile remaining free turning, and as a few others have mentioned one section of the ring felt a lil rough to pass, but seems like nothing more then fresh cut gears needing to be worked in a bit.

I put the truck in Race mode to eliminate reverse, and ran 5 stock NiMH packs through the system before popping in the Lipo. Previously I just went Lipo from the get-go. Still using the stock diff cases, I ran 3 sessions hard and she's holding up.

When I say hard, I found a 5 foot pile of gravel, and hit it maybe 25 to 30 times doing 10 to 15 foot backflips. Backflips landing on flat ground with hard skid plate slaps, it was a blast, and yes I got it all on video, just need time to process the GoPro files. Many crashes and lid slaps not a thing broke.

Basically, I found you set it up tight at the start and run it in slow with stock batteries, it loosens up a bit, you recheck to make sure the breaking in doesn't need a extra shim.

[50togo]

Usually does need one! http://traxxas.com/forums/showthread...-amp-pinion-in

[airmaxx23]

I stripped 2 rear diffs in a week. Third time around, I installed it free, but as tight as it can be while stile remaining free turning, and as a few others have mentioned one section of the ring felt a lil rough to pass, but seems like nothing more then fresh cut gears needing to be worked in a bit.

I put the truck in Race mode to eliminate reverse, and ran 5 stock NiMH packs through the system before popping in the Lipo. Previously I just went Lipo from the get-go. Still using the stock diff cases, I ran 3 sessions hard and she's holding up.

When I say hard, I found a 5 foot pile of gravel, and hit it maybe 25 to 30 times doing 10 to 15 foot backflips. Backflips landing on flat ground with hard skid plate slaps, it was a blast, and yes I got it all on video, just need time to process the GoPro files. Many crashes and lid slaps not a thing broke.

Basically, I found you set it up tight at the start and run it in slow with stock batteries, it loosens up a bit, you recheck to make sure the breaking in doesn't need a extra shim.

It might be fine for a bit but under load the ring and pinion are forced away from each other, that's why the shims are needed. It should feel pretty rough once you shim the diff, especially if you're using something that is quite a bit more powerful than the stock system.

[SiNiST3R]

I'm checking the play after each backflipin session, I just disconnect the drive shafts and inspect. So far they are solid, feel fixed in place. Absolutely no play in the diff, and she rolls as smooth as she's ever driven. I've not added a shim yet, doing so would press the ring too tight against the pinion and stop rotation, as long as I have no play in the diff, no need to shim. Alloy bulks I expect to need shims, but I'm not needing any with my plastic stockers at the moment.

The 2 rings I stripped have been stripped with far less run time and abuse. What would you say is harder on the MERV, a standing backflip, or 12 foot backflip off a gravel jump onto flat road? First diff stripped after a few standing back flips. Second after maybe 3 backflips off a foot high ramp and a wheelie session, third diff has seen standing backflips, 12 foot plus backflips, wheelie sessions, street and football field speed runs and many many tumbles going over the gravel jump. My front diff has not been opened up yet, no need to. So I've got no shims on her at all, except maybe the factory shim on the pinion if I got a new enough model lol.