HELP Need to rebuild my 8.5" boys!

Injectedcutty

Injectedcutty

Geezer
Supporting Member
Nov 24, 2014
5,229
113
Louisville, KY
Alright guys, finally at the stage where I'm contemplating on how to rebuild the rearend in the Cutlass. I have one of the desired 8.5" from a 442 that currently has stock axles, a Richmond powertrax posi and the stock 3:73's. The posi makes some odd noises at low speeds due to a bent axle issue that occured when I acquired the 8.5

I'm not interested in getting a 9" since I know with the proper parts my 8.5" will be strong enough for what I throw at it.

Here is a list of parts that it needs. Any advice on ring and pinion brand is appreciated. I don't mind spending a few hundred on quality gears if the reputation backs it up. Also, forged pinion yokes....I already have a conversion U joint in the driveshaft, just need a new 1350 joint and associated pinion yoke. Quick performance has their brand forged yoke for only $70....seems like a smoking deal if it's strong.
Thanks in advance guys, and I'll update this as needed once parts are acquired and/or installed.
20200414_181735.jpg
 
8

81cutlass

Royal Smart Person
Feb 16, 2009
2,352
113
Western MN
Quick perf has their store brand 30 spline posi on ebay for $280. I asked who makes it and it literally is a Yukon. My first one even came in a Yukon box.

Quick will sell a posi with install kit and gears for $500.

I have the moser axles in my 8.5 and they are good. They come with holes press in or screw in studs. I bought metric studs and they are drilled for press in or screw in 7/16". I hand drilled the press in holes for M12 studs and used Morroso 2.5" studs. I have not been overly happy with the quality of Dorman studs.
 
Injectedcutty

Injectedcutty

Geezer
Supporting Member
Nov 24, 2014
5,229
113
Louisville, KY
Quick perf has their store brand 30 spline posi on ebay for $280. I asked who makes it and it literally is a Yukon. My first one even came in a Yukon box.

Quick will sell a posi with install kit and gears for $500.

I have the moser axles in my 8.5 and they are good. They come with holes press in or screw in studs. I bought metric studs and they are drilled for press in or screw in 7/16". I hand drilled the press in holes for M12 studs and used Morroso 2.5" studs. I have not been overly happy with the quality of Dorman studs.
This is the answer I was needing. I saw there posi and gear sets but didn't have any branding on them. I've heard bad things about the Yukon posi units, but could be operator error as well. Streetbu has a truetrac and said it's super quiet and nice.
Are you running the Yukon posi in your 2+2?
 
Rktpwrd

Rktpwrd

Comic Book Super Hero
Feb 2, 2015
2,760
113
Calgary, Alberta, Canada
X2 on the Moser axels. Money well spent IMO.

As for the diff cover, I’d suggest an aluminum one with the bearing cap preload bolts, as for which one, it’s up to you who’s name you want on the outside. I’m pretty sure one manufacturer makes them for everyone, with just different names on them. The one on my 12 bolt is from T/A performance.

They also look real nice when installed with an ARP polished bolt/stud kit.
 
melloelky

melloelky

Royal Smart Person
Oct 22, 2017
2,205
113
mass
i don't have any experience with the 8.5's but all my dealings with quick performance have been very good.
 
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