A body rear swap

[antman94]

I currently have access to a 1970 chevelle ss 12 bolt rear 4 series carrier. Ive read multiple forms about swapping these rears into a g body (im doing an 86 cutlass supreme 4 door) but ive yet to get a clear answer. I know for sure Id need to change the upper control arms for the adjustable ones, but other than that, is there anything else that needs to be changed for the axle to bolt up? thank you.

 

[rccktmn2]

I put the same 12 bolt into an 84 supreme, it was a 2 door but the same suspension. The 12 bolt is approx 2 inches wider so an inch on either side so your backspacing on the rims will need to add an inch. Other than that it was a direct bolt in except for the upper control arms which will need to be slightly angled outward. The upper control arms will fit but they are tight to get them into the brackets and it will bind a little but other than that it's a direct bolt in. The springs and lower control arms are a direct fit with no modifications.

 

[pagrunt]

Years ago I saw control arm kits to put '64-'72 rear ends in our cars. Can't remember who all made them, believe Jeg's & Summit did sell them. Not sure if they available any more.

 

[rccktmn2]

UMI performance makes the swap upper control arms and I've seen on ebay someone is making them and selling them unpainted. Not too bad of a price if I remember right.

 

[UMI Sales]

Thanks for mentioning UMI!

http://umiperformance.com/catalog/index ... th=8_60_68

Our upper arms are the key component in the swap and are (hopefully) the most popular in the industry.

Factory lower arms work and our poly tubulars are popular as well. For the ultimate lower arm, it's good to have a swivel on the axle side to optimize the angle of the bolt.

Don't forget you may also have to move some spring perches and keep in mind the track width isn't exactly the same.

ramey

 

[pontiacgp]

I have a 67 A body rear and I used the UMI conversion uppers which makes the switch real easy. A 67 rear is 2.5" wider than a G body rear but the bracket for the lower control arm is closer to the center of the rear end so UMI made me custom lowers with a Roto Joint on the axle side to compensate for the angle. The 68 to 72 rear is 4.5" wider than the G body rear and I think the lowers fit without the issues I had. The spring perch does sit further forward but I left them alone and it doesn't seem to bother the spring.

 

[antman94]

Awesome thank you guys so much for the information. Only other question I have is will I need to swap out the yoke/u-joints? or will my factory cutlass driveshaft bolt right up?

 

[pontiacgp]

you'll need a conversion u-joint

http://www.moserengineering.com/other-p ... joint.html

 

[Carlola]

There are a few companies making conversion UCA's. Umi's look good, bit pricey though. I have the same rear in my monte. I had it shortened to G-body width. I upgraded to the 1/2 ton yoke. Will need a custom drive shaft tho.

 

[pontiacgp]

Napa sells the conversion u joint but since you have to shorten the driveshaft you can change the weld yoke to match the rear end yoke