Originally Posted by
Autocratic
Remember, the B4 internal drive ratio is different than the 22. You can't assume that gearing the same will create equal acceleration and speed.
81/23 sounds like a good start with the 8.5.
I had accounted for that. I run 22/76 on the 22 which gives me an 8.39:1 FDR and the 23/75 in the B4.1 would give me an 8.47:1 FDR. The transmission IDR basically equates to 1t on the spur (2.6 vice 2.43 on the 22). I'm certainly not opposed to giving the 81 a shot (which would bump it up to about 9.15:1 with the same 23t pinion), was just curious if there was a specific reason the 81 seemed to be the popular choice due to motor placement. I typically try to keep the motor forward to decrease polar moment but some vehicles actually like the weight further back.