Re: Ring and pinion set up question
 

Try a 0.035" shim between the pinion gear and the pinion, and 0.008" to 0.010" back lash, as measured at the outside end of the ring gear teeth, measured 4-8 places around the ring gear. Make sure you're measuring the back lash with the dial indicator as close to perpendicular to the rotation of the gear as possible.

Re: Ring and pinion set up question
 

Back in the bad old days,I was a line mechanic at a few Chevy dealers. There were still quite a few 12 bolt equipped cars running around out there then, and it seemed that the lower the gear, the thicker the pinion shim needed to be for a good set up. OEM stock gear ratios, 2.73-3.73's seemed to like a .030"-.031" shim, 4.10-4.88's all seemed to like an .032" shim,5.38's and 5.57's seemed to need an.032-.033", and insane ratios like 6.14's might want an .034-.035. .008-.011 on the backlash seemed to be optimal,as well.You are right in the center of the infield with the dimensions you mentioned, but you didn't state what gear ratio you are using. This info should get you started.

Re: Ring and pinion set up question
 

If the pattern comes to a point on the root side, you need to pull the pinion farther away from the ring gear, which in this case would mean removing some pinion shim. That being said, removing shim would move you outside the normal range on shim. I would make sure that the inner pinion race is fully seated in the housing bore as this would give you a false reading.

Re: Ring and pinion set up question
 

Thank you for all of your replies. I will be in the garage working on it tonight,I'll let you know how it comes out. Thanks again.

Re: Ring and pinion set up question
 

Once again,thank you all for the help. I finished with the pattern set-up and ended up with a .028 pinion shim and .009-.010 back lash. The pattern still looked good with a .030 shim,.032 was too deep.I talked with a tech at Strange,he checked with an assembler,who said he normally ends up with a .020-.028 pinion shim with the Strange 12 bolts.On a side note,I had to wrap a shop rag around the pinion between the yoke and the housing to get a good preload on the gears. Then I turned the ring gear with a wrench on the ring gear bolts.Once I did that,I got a very clear pattern. Thanks to Johnny at Motive/Richmond for the tip.