Got an E-Revo a few months ago and finally got it all put together. Im running the mamba monster system on 6S. I keep having problems with the rear diff. Any suggestions or clues as to why? Is 6S too much?
Anything helps! Thanks!!!

It's because traxxas is garbage! It "should" be able to handle a 6s because they advertise and sell it like it can, BUT:

Apparently.

The stock differentials don't really hold up to 6S, no. The problem is that the differential casings (plastic) flex under load and allow the ring and pinion gears to change mesh, which blows up the teeth, as you've no doubt already seen.

This is a problem on both Traxxas Monster Trucks (Maxx & Revo).

Replacing the differential cases with aluminum cases will solve most diff issues you'll run into. The rear diff takes a much harder beating than the front end, so if you're strapped for cash, doing the rear end first is an option that works.

If you blow the spider gears (cup comes apart) later, you can fix that with an aluminum diff cup. FLM makes these for the Revo & Maxx, and they include a modified ring gear that takes larger (M3) screws to boot. Integy, GH, and HR all make diff cups that take the regular M2.5 screws that bolt up to the original gears, however.

If you explode the diffs after that, your only option is the RC-Monster Hybrid diff cases, and those take 1/8 Scale diffs. Problem is, you'll be changing diff ratios (2.85:1 to 3.31:1) so you'll have to regear some.

Hope that answers your question. 6S is fun, but the truck requires some upgrades to handle it reliably.

Wait....hybrid diff case's for a revo? Since when???

I don't know how some of your brains think.... If you buy something with quality money at a HIGH quality price NO ONE should have to spend more money for more parts to make it work properly like they advertise it should. Then they make more money at the parts counter on EXT diff cups and other Jag Off-Mickey Mouse set up's..

Traxxsucks= (The expensive name in RC) for plastic junk and non heat treated metals.

RC-Monster makes them.

Edit: They are currently out-of-stock. RC-Monster Mike says they'll be re-releasing them, however.

Haha, stick a MMM on a MBX and see how long it last on 6S lol. Nitro parts last longer than high end brushless, because they have less punch and harshness off the line, brushless are pretty near instant. I know, I've run them both. If Traxxas is the only crappy truck out there, why do manufacturers sell upgrade parts for almost all other brands as well? Because they all push the limits on parts, that's why. You're vitriol sounds personal to me and really doesn't contribute to solving his problem. Maybe he should go into the programming of the Esc and turn the punch down. More like a nitro.

Eta, Jr, a MM on 6S puts out 5-6 HP, that's extreme for a 1/10th car. No matter what the brand.

There is a big difference in a "upgrade" and/or a CRUTIAL/VITAL part to let it run like they say it can...

Vitriol? Nil.

EDIT: Let me add something, he never asked for a "solution"...... He only asked "WHY"..

Why? Because 6S is brutal for ANY 1/10 car. He asked if 6S was too much, Yes, if he's bashing and doing 25 foot jumps and backflips. Speed runs, probably not. Maybe he just doesn't know what the limits are yet and needs advice.

As mentioned the plastic diff case flexing is an issue, but the Revo ones do better than the Tmaxx ones ever did. Another thing is shimming the diffs to get rid of any play (too loose) or notchiness (too tight). You can play around with those stupid Traxxas Teflon washers but it's really best to get the right size shims for the pinion and the spider gears. Unfortunately you can only put shims on the pinion with Traxxas diffs, there's no room for them on the sides. Another thing is to get rid of any play in the drivetrain. Play causes shock loads to be transmitted everytime you gas or brake and they'll find the weakest link eventually.

+1 on that. The plastic shafts flex, so if you're still running into issues after replacing the diff cases and cups, this is something to look into once you're at that point. Shock loads are bad for anything in the driveline.

I have an e-maxx with a MMM 2200kv setup and have also had to replace the rear diff gears twice. In both instances, the rear diff gave out when landing standing backflips with the throttle still on, on 6s, sporting summit wheels and tires, complete set of steel driveshafts, with the slipper locked. Other than those two occasions, I've had no issues with jumps, wheelies, and general tearing up some grass and dirt.

From my experiences, no, Traxxas does not 'suck'. There is the same amount of logic in stating that they don't make their parts strong enough, and that they put too much power in their product. Personally, I'd rather have more power than the chassis can handle and use it smartly than have an underpowered chassis within the same price point. Of course, lots of power in a chassis that can handle it is best, but when choosing two from 'powerful/bulletproof/inexpensive'....
I think arguing that a brand 'sucks' because certain parts can't handle extreme abuse at the max ratings is a bit silly. The fact is electric motors have a much higher torque output relative to the watts/HP, and is near instant, when compared to nitro engines (which is what the diffs were originally designed for). Certain parts could be made better, which is what the aftermarket is for.

IMO I don't think they really flex that much, maybe a little at the ends but the splines keep them from twisting much in the middle. Either way I feel the bigger problem is the holes for the universals go from circles to ovals as you use the vehicle. This creates play, backlash and shock loads in the drivetrain.

If I owned a RC company, your my target customer! Oh yeah, they don't own the motors or the speedo's that their drive train can't handle. You don't need "extreme abuse" to grenade a traxxsucks diff, all you need is a 6s and a trigger finger. You act as if I don't know what I'm talking about, I've probably owned more traxxsucks garbage RC at one time or another then all the posters in this thread combined....

Well thank you everyone for their input! Maybe I should have worded it differently. Of course Im looking for a solution not just asking why. I know 6S is a lot of power, but man is it fun!