Limited Slip Upgrade

Hi,

I have what I believe is an 8.5" rearend in a '71 Skylark convertible. The car originally had a 350/350.

Can I upgrade this to a posi? What exactly needs to be replaced to get this done, and are the parts available in aftermarket?

I don't know what my gear ratio is...I'm assuming I'll go with what I've got for now...but if I elect to change the ratio later, same questions; what's required, and how available are the parts?

Finally, is this "do it in your own driveway" kind of work? Or do the smart guys let the local drivetrain specialists do it?

Thanks,

Jay

 

it needs to go to a shop, its a percision set up that has to be acurate not just a bolt in operation. you can get your unit replaced with a posi and can get just about any gear you want. if your getting it done i would sujest getting a gear set at the same time. its not that much more and will cost more if done in the future. with that said an other thing you can do is swap a whole rear end, which can be done in a day in the driveway. this dont require a ton of skills, most of us can do it ourselves. its only 4 bolts on the drive shaft, 4 on the control arms, 2 for the shocks, unhook the brake lines and emergency cables. then put the new one in and do the same. i just removed one today and it took a couple hours with hand tools in a junk yard. i started by removing the driveshaft and lower shock bolts, i cut the brake line and cables but they can be removed in your case. then i put stands under it and jacked the rear end up to take the weight off the control arm bolts, then took out the uppers then the lowers but left the bolts in part way. i then lowered the rear end slowly and the springs fell off and it goes to the ground. i got the last two bolts out and draged it out. hope that helps

 

You have the corporate 8.5"

If your car was a 2bbl, you have a 2.56 rear
If your car was a 4bbl, you have a 2.73 rear

If you have a 2.56, go with a 3.08 gear set-up.
Best for all around driving.

If you have a 2.73 you can keep those or upgrade to a 3.08.

Read the article on our site about finding and removing posi units.

You will need to take your car to the shop to have the rear set-up.

While you are there, replace all seals and inspect bearings.

 

Thanks guys....great information & advice!!