GM 10 Bolt 8.625 Rear Differential Carrier Bearing Measurements

[Amp Wrangler]

Hi GMT800 Family,

I have a '99 2WD 1500 RCLB and I'm planning to upgrade the open rear differential soon to a Eaton Truetrac helical-gear limited-slip carrier. While I'm in there, I also want to swap in a 3.73 gear set.

Two questions:

1. Do the 8.5 and 8.625 rear differentials share the same carrier bearing footprint?
2. Does anyone have the exact carrier bearing measurements for the 8.625 carrier?

Our friends at dnracecars.biz have agreed to fabricate an ingenious tool to take a lot of the guesswork out of setting pinion depth, but I need the measurements first.

Thanks in advance for your help!

 

[stutaeng]

Interesante...

Do you know how that tool works?

On your first question, I'm almost positive they are the same. I believe those two variants are identical except for the slightest larger ring gear on the later version.

 

[Amp Wrangler]

Interesante...

Do you know how that tool works?

On your first question, I'm almost positive they are the same. I believe those two variants are identical except for the slightest larger ring gear on the later version.

It's based on finding the centerline of the carrier/axle and then measuring the distance to the pinion face. Once that measurement is known, you can determine the correct shim for proper pinion depth.

GM 8.5" 10 Bolt Pinion Depth Plate | DNRC Webstore

This tool makes the perfect addition to the ring and pinion setup tool kits offered by Jegs and Proform (pictured). Provides much more pinion depth measuring accuracy than the pivoting piece provided in those kits. Finished product is sandblasted and cleacoated. Made from 3/16" high quality raw...

www.dnracecars.biz

 

[stutaeng]

It's based on finding the centerline of the carrier/axle and then measuring the distance to the pinion face. Once that measurement is known, you can determine the correct shim for proper pinion depth.

GM 8.5" 10 Bolt Pinion Depth Plate | DNRC Webstore

This tool makes the perfect addition to the ring and pinion setup tool kits offered by Jegs and Proform (pictured). Provides much more pinion depth measuring accuracy than the pivoting piece provided in those kits. Finished product is sandblasted and cleacoated. Made from 3/16" high quality raw...

www.dnracecars.biz

Cool. I believe Kent Moore made some dealership/OEM tool that somehow did the same thing? Overly expensive, as are all Kent Moore tools, of course. Lol

 

[Amp Wrangler]

Cool. I believe Kent Moore made some dealership/OEM tool that somehow did the same thing? Overly expensive, as are all Kent Moore tools, of course. Lol

They sure are. I was blessed to be able to work in a Chevrolet dealership through high school and college. Best I can remember, it was a thick tube—almost like conduit—that you bolted in place of the carrier with the bearing caps torqued down, and it had a few arms and plates to get that measurement. Expensive and complicated—looked like a torture device lol!