I currently have a 3.73 worn out limited slip rear with drum brakes. I pulled a disc brake posi rear from a 86 T/A that a guy had bought for a braket-racer project and ran out of $. He said it was a 3.55 rear which would be about perfect for my planes but I havent checked it yet.

Anyway Ive changed my rear before it wasnt that hard. But what has to be done to convert the drum bakes to the discks on my new rear. I mean do drum and disc use the same lines and all?

 

You just need the proportioning valve up front by the master cylinder fer the disc brakes, as they require a different amount of pressure - but we did that swap a few weeks ago on someones car without the proportioning valve swap n his brakes are fine.

 

also one thing we ran into was the hard lines that go into the main rubber line had metric threads on the 9 bolt. the 10 bolt was SAE threads. but that car was an 83 also. so we took the ends off the 10 bolt and put them onto the lines on the 9 bolt. then flared the lines. couldn't just swap the rubber line because of the same thing. the place where the rubber line bolts has a 180* bend right there. so no room to cut and reflare.

here is a pic of the ends

http://www.thirdgen.org/techbb2/show...hreadid=180576

 

You shouldn't have a problem with line fitting threads or anything of that sort since they're both '86 rears. Just get the proportioning valve out of the donor car (or order a J65 prop valve from GM if you have to) and you'll be good to go.


I swapped an '85 9-bolt into the place of my stock '91 10-bolt (using a new '91 prop valve from GM) and everything bolted right in. The 9-bolt rear discs are not fun to adjust though....so consider yourself warned.

 

Ive never adjusted any brakes at all so yea that should be an experience. And I ASSUME its the right rear for teh 86 T/A I got it from. I was told it was a 3.55 but Ive never heard of 3.55s coming in a 3rd gen. Did they ever? The T/a was originally a TPI 5 speed but motor and tranny were gone.

 

3.45's came stock in the 9-bolts behind 305TPI/T5 combos, maybe the guy you talked to wasn't quite straight on his info? Or maybe he just used the easy-but-inaccurate "turn the wheels over once and count the pinion rotations" method of finding the ratio.

If it's a 3.45 then that's great...it's a sought-after ratio, and perfect for a TPI car. The only factory ratio that's harder to find is 3.70.....they only used them for one year. I didn't even know you could GET factory 3.70's until I bought my 9-bolt (it has a set.)

3.55 I believe is a Ford 9" ratio.