Posted by Greg Coffin [172.68.2.109] on Sunday, February 22, 2026 at 18:59:28 :
In Reply to: Re: Ring and Pinion Tooth Pattern posted by Glenn [172.70.100.187] on Tuesday, February 17, 2026 at 09:45:05 :
Glenn, I've read both your posts about your contact pattern and there are a couple things I'd like to point out about these third members and how they are set up. I'm going to get pretty basic on some of this, so if you are already familiar, my apologies.
First, your contact pattern looks pretty good. To get it better you can move the ring gear closer to the pinion. Your target for ring gear lash is 0.006", so try that and see if the pattern improves.
Second, changing the pinion shim only changes the preload of the large pinion bearing. It does not move the pinion shaft in or out.
The location of the pinion is determined by the pinion gear resting against the large bearing cone and cup. I'm assuming you thoroughly cleaned the third member housing before assembly. Any dirt in the bore for the large bearing cup can push the pinion in too far and mess up your pattern.
Third, it sounds like something is amiss if you were getting the same torque reading regardless of the spacer you were using. Did I read this wrong? Your target here is 40 in-lbs. And just a reminder that these numbers are in INCH-POUNDS, not foot-pounds (been there, done that).
There are a number of decent write-ups on differential set-up. The best I have found is from the TM9-8031-2 for the M37s. You can buy just Chapter 6 (differential assembly) from Portrayal Press, rather than the whole manual. It has excellent pictures and descriptions.
Good luck and let us know how it goes.