I have a 12 bolt rear out of a 69 Grand Prix , will it fit in my 86 MCSS? I know the control arms are different but that does'nt worry me, I am more conserned with the width. Are the stock axels 30 spline?? Take Care gunslnger
12 bolt in a g-body
- Thread starter 1gunslnger
- Start date
Wish I could see a pic of that 12 bolt you have...I don't even know if they came from the factory with a 12 bolt rear...that being said...I put a 12 bolt from a '69 CHevelle into my '84 Monte .....Bolted right in with the 12 bolt swap kit from UMI---Iceman also makes this swap...the swap kit replaces your stock trailing arms is all....Hope this helps.
Yes it should bolt in just like the chevy 12 bolt, the mounting points should be the same, but be forewarned, the pontiac(B.O.P.) 12 bolt rear is not internally the same or as strong as a chevy 12 bolt. Do a little research on that rear end before you spend a lot of $$$ on it. A pontiac 12 bolt rear will have a 12 bolt cover, but has a 10 bolt ring gear that is IIRC a 8.2" or something close. Also has a small diameter pinion gear shaft. Chevy 12 bolt is 8.75" ring gear with 12 bolts attaching the ring gear and also 12 bolts attaching the rear cover. Like I said, just do some checking on it.
The BOP 12 Bolt is basically a 10 bolt 8.5 in a 12 bolt housing. The chevy 12 bolt has an 8.875 ring gear.
12 bolt chevy or any 1968-1972 a-BODY gm MUSCLE CAR REAR WILL BE ABOUT 3" wider than your stock g-body rear 1978-1988 era.
Upper mounts will be in different location lower control arm mounts will be slightly wider out board than the g-body and the spring perches again are slightly off not centered over the axle tube and out board from the stock g-body rear.
All these slight and little differences can and will cause some binding ...I have seen many ignore this and pull and tug till it fits twisting and bending parts re drilling holes till it fits ...
Still have to deal with more backspacing on rims also you will need at the very least 1" extra negative backspacing on each rim. 4.5 5 or 5.5" will usually do it.
One of those deals where all depends on who you ask as to how easy or hard it is to fit ..IF you do not deal with mods well and have a mind for ideas for suspension geometry then may be over your head.
JIm
Upper mounts will be in different location lower control arm mounts will be slightly wider out board than the g-body and the spring perches again are slightly off not centered over the axle tube and out board from the stock g-body rear.
All these slight and little differences can and will cause some binding ...I have seen many ignore this and pull and tug till it fits twisting and bending parts re drilling holes till it fits ...
Still have to deal with more backspacing on rims also you will need at the very least 1" extra negative backspacing on each rim. 4.5 5 or 5.5" will usually do it.
One of those deals where all depends on who you ask as to how easy or hard it is to fit ..IF you do not deal with mods well and have a mind for ideas for suspension geometry then may be over your head.
JIm
