12 bolt swap

[h2opunk182]

Can anyone tell me if it is difficult to swap the rear.. im going to be putting in a 12 bolt i already bought the umi upper and lower arms for it http://www.umiperformance.com/3019 and know i am going to need to shorten the drive shaft.. but other than that i really cant find any info on the swap, of how, what im going to need, etc.. Its going in an 85 MCSS

pretty much this is my first time doing the swap, unemployed and don't want to spend more $$ then i have to.

 

[TNTS79]

It's not that difficult of a swap if you have the adjustable uppers and lowers. I had a set of hpm uppers I was cussing the whole time, ended up getting a set of lower adjustables and go everything in and set up. Just got my set of 10" slicks and I am gettin ready to take it to the track! FYI, I did my rear swap in a rock driveway! ](*,)

 

[bowtie81]

depends on what year 12 bolt it is, youll need to get different back spacing on your rims. mine is out of a 66 chevelle and i have 5.5 b/s. watch for clearance issues from the inside lip of the rim to the shock bolt. different u-joints. My spring perches were in the same spot as the 7.5 rear. other than those few things its a pretty easy swap. if i have forgotten anything one of the other guys on here will fill it in.

 

[TNTS79]

I had my 12 bolt narrowed to factory g-body dimensions and ordered a set of moser axles with c-clip eliminators so I cant help with the backspacing issue...

 

[h2opunk182]

awesome thanks for the info.. i already have a set of 28x10.5 thats going on the car.. my big question is the breaks.. i want to replace the lines coming off the rear and its been sitting for a while.. is it a good idea to chance anything inside (fluid) or anything inside the drum?

 

[bowtie81]

yeah its not a bad idea to change the fluid that way you can see how the gears look, you may need a bottle of rear end conditioner. Replace any lines that look crappy.

 

[h2opunk182]

Alright so i just bough the lines and the fluid.. now i have the fun of trying to get the bushings out to put in some polys..

I have stripped countless bolts with my bushing removal tool accomplishing nothing in the process, i am pretty much about to resort to a chizzle and a torch..

how has anybody else gotten the bushings out of the ears with out throwing a wrench 1/2 way across the neighborhood

 

[TNTS79]

I had mine pressed out and the new polys installed at the shop when it got narrowed. Pretty sure you can drive them out with a dead blow, just be be sure to not hit the cast iron ears of the rear end housing. If the bushing sleeves are in bad shape, rusted etc... let them sit for a day or so after a good coating of good penetrating oil like KROIL. Also clean up the part of the bushing that will be going through the ear of the casting with a wire wheel or something similar. Big pair of vice grips on the outward side and try to get the bushing to rotate, if you get it to rotate you should be on your way... Good luck!

 

[h2opunk182]

oh trust me i tried the dead blow.. that was a lost cause about 5 min in... that was actually my first idea

 

[Barry 85 SS]

I ran a drill bit through the rubber part of the old bushing all the way around until I was able to get the center part out. Then I was able to knock the outer metal part out using a chisel to fold it in.