XXX-CR Diff

[i4n]

Hi All,

I have a slight problem with my XXX-CR diff, the 51 tooth gear that holds the diff balls and the out drives etc keeps exploding when I try to gear the car up for some speed runs around the local car park. I'm running a Mamba Max 6900 combo on 6 4200 Demon mAh Ni-Mh cells. When I run it with a 17/86 gearing everything seems fine but when I try to gear it up for faster speeds (27/80 ish) it breaks as soon as you throttle up?

What happens is the centre portion breaks away from the outer portion where the holes for the diff balls are. The diff is built as per the kit instructions (using the copper shims in the diff and not on the outside) with the correct grease being used (Losi transparent silicone stuff on the balls drive plates and the creamy white stuff on the thrust bearing) and adjusted correctly (smooth, but with a little bit of resistance) and it is definately not slipping. The slipper is adjusted, if anything, a bit too loose to try and control the stress going through the diff.

Is it just a case of the Mamba 6900 produces so much torque with the higher gearing that the forces developed just rip this part apart? Or is it that I have the diff adjusted too tight and as such isn't rotating properly in the diff action?

All I want to do is some of the insane speed runs like you see on eBay to get it out of my system and then race it properly during the summer................

Cheers for any help.

Ian

[sparrow.2]

Sounds like you are running your diff too loose and it is overheating like mad, causing your diff gear to disintegrate/melt.

Tighten your diff as per instructions, then tighten your slipper fully and with your thumb on the spur gear try and turn the left tire while holding the right one tight. if you can, your diff is too loose. Tighten it until it doesn't slip anymore, then adjust your slipper to slip for about two feet on takeoff or so.

That ought to stop you obliterating your transmission...

[i4n]

Cheers mate I'll give that a try later on.

On the upside, I can now rebuild my diff with my eye's shut.......