setting a rear pattern

[grumpyvette]

Gonein420 posted this question

Hello, all just a little help with my NEW ring gear pattern? Pics attached. So I am getting a decent coast side, maybe a little close to the heel. The drive side seems a too close to the toe. Pinion depth seems ok, now. So my shims are 0.241 and 0.2485 on the ring gear side. Perfect .009 backlash, wants .008. I switched the shims which made an almost a perfect pattern but the backlash jumped to .017, a no no. So my thinking is, do I need to add a some shim to pinion, bringing it closer to the ring gear? I don't have a bearing splitter, so I'll have to wait getting the bearing off again. The pattern seems very close, compared to images I've seen on the Net. Maybe a .005 change in backlash will work out better? I'll try later tomorrow, please help? Also, does the math work? Ie: As I added 0.075(0.08) to the ring gear side, it added 0.075 to the backlash? Same for the pinion?


I re-used all stock shims, the pinion shim is 0.028. So I'm thinking this pattern is close enough, anyone have similar thoughts? I can increase backlash up to 0.012 to get the pattern a little more centered, as the variations call for 0.004 +or-. I think I'm going to subtract 0.003 and see what happens. I'll keep you posted.

Also, lookin at the pinion in the second pic, the pattern looks a little high on the drive side. Would dropping or subtracting pinion shim thickness some solve this?

 

[northrnyankee]

It's mentioned it's a new ring gear, is the pinion gear new as well and from the same set?

 

[gtr1999]

The pattern looks very light, make sure your paste isn't too thick- add in some gear oil. Also I would blend in that case and remove the rough edges. I build the posi and open cases first then start to pattern the gears. I like to apply some drag on the pinion while rotating the RG by the RG bolts, and as a final setup use and axle to spin them. Doing that on a full diff may be a challange but on a 63-79 vette it's easy. You want a equal pattern on the length of the tooth, it may be to the heel or toe sometimes. The important thing is to keep both sides equal. I see a little taper off the drive side but can't clearly see the coast pattern.

Here is one of the vette patterns I got with some US Gear 373's