Help with build a strong diff ! What to use?

[Maxx42]

The hybrid bulks should be compatible with the G4 chassis. I bought them to use with my G3 chassis and they are a perfect fit. Also as stated above, you really should use the buggy diffs instead of the truggy diffs (the truggy diff ratio isn't necessary in your emaxx).

[ssspconcepts]

The hybrid bulks should work fine. I don't have a G4 but I would assume the G3 Maxx and FLM hybrid bulks would fit just fine. Especially considering that the 3905 basically uses the same bulks as the earlier Maxx version. Therefore it is safe to say that the G4 will also work fine with the earlier bulks (to include FLM hybrid bulks).

If you already have purchased the truggy diffs...I think you could keep them and just use a pinion gear that has a +2 or +3 tooth count and you'd be fine. Sometimes this is the best option anyway given the size of the large Neu 1515 series motor and the resulting limitation it imparts on what pinion sizes you can use with the stock motor mount (or most aftermarket motor mounts for that matter).

[Maxx42]

Originally Posted by ssspconcepts

If you already have purchased the truggy diffs...I think you could keep them and just use a pinion gear that has a +2 or +3 tooth count and you'd be fine.

It's actually a little more than you'd think, given the spur gear that he may be using. If he's using the 65 tooth spur gear, he would have to add about 6 teeth to his pinion to get the same rpm's at the tires, or he would have to lose about 15 teeth off of his spur gear if he kept the same pinion.