Diff Problem? Please Help!

[maxmannnn]

After pushing my converted BL muggy pretty hard today it has developed a grinding sound upon acceleration. It only does it when I really hit the throttle hard. Is this a diff problem? I've checked and re-checked the mesh and I can't tell if that's what is griding or not. Also, I'm running a slipperential.

I've poured over the forum for a couple hours and can't seem to find an answer.

Some gear is either deflecting under load or is worn out on one of the diffs. If it doesn't do it when braking hard on pavement but does it on a hard acceleration I'd suspect the rear diff ring/pinion.

[maxmannnn]

I've read a lot of other posts talking about making certain to correctly shim a diff. What is the procedure to correctly shim a rear muggy diff? (aluminum case). Thanks for being patient with a newb.

[simplechamp]

Could be the spider gears inside the diffs. I'd check those next.

I think I remember someone had a similar issue, and it turned out the hex screw on the center cvd had come loose. You could check those hex screws just to be sure. Less work than taking a diff apart.

I've had it happen when the motor pinion teeth were rounded out just enough to slip under load as well. Fact is, the gears can look ok but are really rounded down at the tips of the teeth and loose mesh will make this happen. Try shimming behind the inside bearing of the rear diff pinion a bit so it can't move forward and backward so much and make sure the cvd cup on the other end of the pinion is slide all the way against the pinion before tightening the cup. Otherwise the pinion can move in and out away from the ring gear.

[bdebde]

The muggy with big tires can be hard on diff bearings; once the bearing gets worn out it allows the gears to deflect past each other. Usually on the pinion bearings in the rear, check those if no other obvious gear problems.