posi rear end upgrade

[scarborough]

weld the axle tubes? check
put a cast differential cover on?
change out axle shafts?
replace with new differential with which gears?
don't forget to install new dog ear bushings, pinion gear crush bearings, and convert the drums to rear disc?

I wouldn't pay more than $100 for a used axle you're going to strip down and do this to

The car is just a daily driver with a mild upgraded 455 /rebuild th350 transmission. it will not see any track time. I read that welding the tube to the housing will help strengthen it. not sure if that's so, just thought I would give it a shot
I plan to add a set 28 spline axle
3:23 or 3:42 gears and up grade the cover. one these days I hope to learn how to post picture of my project. over the years I have received a LOT of good info from this group, and its has help me a lot. I would like to say thanks to everyone who has responded to my post.
and Merry Christmas and Happy New Years

 

[olds307 and 403]

What posi do you plan on running?

 

[melloelky]

Merry christmas.the spline uprgrade is a good idea.
keeping AWAY from sticky tires and a std trans it will live a longer life.

 

[Bob Paul]

My original plan for my Regal was to take it to a Ring and Pinion shop and have them upgrade my 7.5 to a 28 spline carrier with Moser axles and new bearings and seals, since I am currently only running a 355/200R4.
But since it was only a few hundred dollars more to get the QP 9" and build it here I went that route and the price difference more than covers the fact that I now have 31 spline axles in a brand new housing (instead of my rusty 7.5" housing) and new 11" brakes versus my factory 9" used brakes.
Plus I tend to upgrade engines so it is best to have a foundation I can build on if that happens.
Another thing to consider with the 9" swap is you may need a different length drive shaft, I ended up getting one from Denny's and it was very nice.
View attachment 232746View attachment 232747

I would like to build a posi 7.5 rearend for my cutlass. i found a donor on craigslist, the rearend looks a little rusty from setting outside. just wondering how much rust is too much to mess with. plans are to have the tube welded to the center section hoping it will help strengthen it up a little. I'm using a donor so the car wouldn't have to set while it's getting rebuilt, or would it be best just to use the original rearend.

If ya want 2 do it cheep way use 66-67 nova axles get a 88'+newer 28 spline carrier either posi er open+put mini spool in open carrier..[ I just weld'd mine cause I'm really cheep ]that's switch's it all 2 28 spline instead a 26....quite a bit stronger......all I had 2 do different was slite grind'n on the spider gear pin cause buttons on c-clip part a 28 spline axles is a cun
t/hair thick'r.....I did this in my 85 Cutlass with a 477 B.B in it+never broke it...it ran low 7's thru
the mufflers in 1/8th........

I would like to build a posi 7.5 rearend for my cutlass. i found a donor on craigslist, the rearend looks a little rusty from setting outside. just wondering how much rust is too much to mess with. plans are to have the tube welded to the center section hoping it will help strengthen it up a little. I'm using a donor so the car wouldn't have to set while it's getting rebuilt, or would it be best just to use the original rearend.

 

[64nailhead]

I'm with others here, there is only one way to cost effectively upgrade a 7.5 before you overcome the cost of an aftermarket - used parts and doing the work yourself.

If you're looking for used parts, then look for a used 4th Gen Camaro/Firebird Torsen. If your tires are 26" or shorter, then you can get away with a 2 series or a 3 series. 2WD S10 28 spline axles will work with a 3/16" shim behind the backing plates.

Regarding welding the tubes, I guess. But the strength issues are the gears and 26 spline axles, not the tubes. You can spend all of the money you want, if you have $15-1800 to invest in the 7.5, then don't upgrade the 7.5, but rather buy a bolt in 9". Head off to the local circle track speed shop and they are relatively cheaper than you can find them online.

Good luck - Jim

 

[scarborough]

I'm with others here, there is only one way to cost effectively upgrade a 7.5 before you overcome the cost of an aftermarket - used parts and doing the work yourself.

If you're looking for used parts, then look for a used 4th Gen Camaro/Firebird Torsen. If your tires are 26" or shorter, then you can get away with a 2 series or a 3 series. 2WD S10 28 spline axles will work with a 3/16" shim behind the backing plates.

Regarding welding the tubes, I guess. But the strength issues are the gears and 26 spline axles, not the tubes. You can spend all of the money you want, if you have $15-1800 to invest in the 7.5, then don't upgrade the 7.5, but rather buy a bolt in 9". Head off to the local circle track speed shop and they are relatively cheaper than you can find them online.

Good luck - Jim

Thanks for the advise, it's well taken. I'll working at it. the 455 run like a turd with stock gears.