Ring and pinion questions

LedSled · Feb 21, 2017

I'm looking for input on ring and pinion gear sets. I purchased a 8.5 GN rear. I want to build into a posi 3:73. A rear guy I once talked to said I should look for oem gm gears but I'm not able to find them. I see some listed as oem but not sure if legit or not. I know I don't want Richmond. I have them in a 7.5 rear and they are noisy. I see gear sets from $100-$400. Not concerned about price as much as quality. Will be a street car but I want to build it right. I'm looking at a set now that is listed as NOS and is a GM part with GM packaging. What is NOS? Manufacturer or acronym for something else?

Also, based on what I've read the pinion is 30 spline. Is that correct?

pontiacgp · Feb 21, 2017

If you don't like Richmond, Yukon and US Gear are made in the US. GM didn't machine the rear end gears, they were done by a 3rd party. And yes the pinion is 30 spline

lilbowtie · Feb 21, 2017

NOS = new old stock

airboatgreg · Feb 21, 2017

If it's noisy odds are it was not set up right. It is an art to setting up a rear end properly. Lots of things to consider

81cutlass · Feb 21, 2017

It might be best to find a low mileage factory set out of a pickup or something if you want to go that direction. There was a lot of vehicles with the 8.5 and most of the time the factory sets are matched so you can just pull them out of the original rear and transplant the gears into a new one and be fine.

American axle and mfg. made the original gears for GM. I think, or at least they did in the 90's.

64nailhead · Feb 21, 2017

Check out Quick's Performance. About the cheapest you'll find and quality stuff. Excellent people and customer service.

Are you planning on a bearing kit and rebuild of the posi?

pontiacgp · Feb 21, 2017

airboatgreg said:
If it's noisy odds are it was not set up right. It is an art to setting up a rear end properly. Lots of things to consider

That's what I thought when I read the first post but I looked up a few threads about Richmond gears being noisey and about 1/2 of them find the gears noisey and some took it to a shop because of the noise and found that the gears were set up correctly.

ssn696 · Feb 22, 2017

I can offer a set of factory 3.42s that came out of my GN axle. About 80K on them. I put in Richmond 3.73s and an Auburn.

Bonnewagon · Feb 22, 2017

I build my own rears and I prefer GM gears also. I usually get them used at swap meets where I can inspect them up close. The guy I trust the most is John Giovannini who has always hooked my up with what I needed. He has a company called Gevo's Rears and Gears located in Saranac Lake, NY. http://www.rearsgears.com/ His parts are top shelf and he can answer any question you may have.

pontiacgp · Feb 22, 2017

Bonnewagon said:
I build my own rears and I prefer GM gears also. I usually get them used at swap meets where I can inspect them up close. The guy I trust the most is John Giovannini who has always hooked my up with what I needed. He has a company called Gevo's Rears and Gears located in Saranac Lake, NY. http://www.rearsgears.com/ His parts are top shelf and he can answer any question you may have.

Mark, do you have any info as to made the GM gears in the G bodies. I know Dana gears were used in GM and Chevy truck and the Corvette from the mid 80's to the mid 90's used Dana gears.

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Ring and pinion questions

LedSled

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lilbowtie

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airboatgreg

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81cutlass

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ssn696

Living in the Past

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Lost in the Labyrinth

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