HELP Need to rebuild my 8.5" boys!

[Turbo Zach]

He is a hard core drag racer from back in the day. Used to be in drugs pretty heavy. Used to be if he was sober he knows his stuff, but if he was doping good luck taking to him. That is why I didn't like him. You are forgetting about one big purchase. A/C for the wife and kids! I know you don't need it, but they seem too. I am giving you a hard time because I want you to get it out for the summer and enjoy it and not do what that guy from Texas did. Drive it once and end up in a never ending rebuild.

 

[Injectedcutty]

He is a hard core drag racer from back in the day. Used to be in drugs pretty heavy. Used to be if he was sober he knows his stuff, but if he was doping good luck taking to him. That is why I didn't like him. You are forgetting about one big purchase. A/C for the wife and kids! I know you don't need it, but they seem too. I am giving you a hard time because I want you to get it out for the summer and enjoy it and not do what that guy from Texas did. Drive it once and end up in a never ending rebuild.

Lol, no AC in this car. If I get to build another hotrod it'll definitely be decked out with all the creature comforts, not the Cutlass though.

 

[64nailhead]

A/C? Power windows will do lol.

I'm with Zach, run it. The rear will let you know if there is an issue in the 1st 500 miles. Spare rears are readily available for our cars as well if you get in a pickle.

 

[Injectedcutty]

A/C? Power windows will do lol.

I'm with Zach, run it. The rear will let you know if there is an issue in the 1st 500 miles. Spare rears are readily available for our cars as well if you get in a pickle.

There is more than 500 miles on it already, had it in the car since 2005ish. I'll continue to acquire parts, once I have everything saved up and ready I'll still get it done because it will make me feel better.

 

[Injectedcutty]

Alright, question for the GM rear guys. I've decided to keep with 3:73 gears since it'll still allow a decent cruising rpm with the 4L80E.

I've been thinking about doing the truetrac install at home, and if I pull the ring gear and it looks fine I can leave the pinion installed correct? If so, then I just swap it over to the eaton diff, install same shims to check backlash, pattern, etc, then assemble if/when good right?

I can take the diff to get the bearings pressed on and do the rest at home after picking up a dial indicator. It's always good to learn something new, and if it saves me several hundred bucks then I'm all for it. The current u joint is plenty strong, and I can keep the forged yoke on standby if it's needed down the road.

Thanks guys, y'all rock!

 

[pontiacgp]

I would check to make sure the seal is not leaking and if not I'd leave the pinion in place. When removing the crown gear remember the bolts are left handed thread. Keep the caps so they go back on as they came off and keep the left and right sides of the carrier shims together and mark the left and right sides. They would give you a good starting place and may even give your the correct backlash.

 

[L92 OLDS]

I would check to make sure the seal is not leaking and if not I'd leave the pinion in place. When removing the crown gear remember the bolts are left handed thread. Keep the caps so they go back on as they came off and keep the left and right sides of the carrier shims together and mark the left and right sides. They would give you a good starting place and may even give your the correct backlash.

The pinion seal can be replaced without moving the pinion.

 

[pontiacgp]

The pinion seal can be replaced without moving the pinion.

If the seal is leaking I always remove the pinion so check the condition of the bearings and races. The seal leak is usually indication of some wear.

 

[L92 OLDS]

Alright, question for the GM rear guys. I've decided to keep with 3:73 gears since it'll still allow a decent cruising rpm with the 4L80E.

I've been thinking about doing the truetrac install at home, and if I pull the ring gear and it looks fine I can leave the pinion installed correct? If so, then I just swap it over to the eaton diff, install same shims to check backlash, pattern, etc, then assemble if/when good right?

I'm running 3:73 gears with a 4L80E and the gearing is fine on the highway. I've swapped in posi carriers into a lot of GM cars and have never had issues. Just make sure you have a shim kit on hand. I say do it yourself....

 

[81cutlass]

If you pull the yoke or seal you "should" swap the crush sleeve.

I have swapped diffs in 3 GM rear ends and kept the same gears and I've never had to re-shim the pinion or backlash.

Most of the backlash variation lies in the gear itself.

I would

Pull old carrier and ring gear
Loosen pinion nut, remove seal and yoke
Inspect pinion bearings. Are you replacing them?
Tighten old pinion nut (with the lock collar cut off!) and old crush sleeve to almost zero preload without the seal
Swap ring gear on carrier and install using factory shims
Check pattern and backlash
If its good pull the carrier, remove the pinion nut and old crush sleeve. Insert new seal and crush sleeve and nut. Torque to whatever preload is recommended
Install carrier & ring gear assembly