I plan on doing the swap in a 1984 trans am .I have been doing alot of reading and just have a couple questions. I have found in my readings that there is 2 different styles of 9 bolts .One with calipers on the same side 89-92 and one with calipers on opposite side of the axle 82-88. Why should I stay away from a 9 bolt 82-88 with the calipers on opposite sides. I have read also that there was a recall on the 82-88 9 bolts. What was the recall. If I am looking at getting a 9 bolt from 82-88 what do I look for to see if the recall was done. Is a 9 bolt from 82-88 even worth buying if it is in perfect condition or should I try to get one form 89-92. Also I am wondering about proportioning valves , I have drums at the moment. If i use a rear from 82-88 will I need a proportioning valve for them years . Any info would be really appreciated , and Thanks in advance.

 

Do you just want to convert to rear disk brakes?

 

Well the thing is I have a non-posi 10 bolt rear right now with drums and it has 26 spline axles. I want to upgrade to a posi with at least 28 spline axles. I have a lead on a complete 9 bolt . I was told all 9 bolts have 28 spline. I thought I would try a 9 bolt , to upgrade mine I need a new carrier and axles plus gears . So it would problay cost the same as a swap . I would love to try disc also .

 

9 bolt rear ends are fine if that's what you want or have access to. Is it the gear ratio you want? Make sure. The biggest drawback to the 9 bolt rear is that they are hard to find parts for if they need rebuilding or if you want to change gears.

If you're converting to a disk brake rear you'll need a new proportioning valve and possibly a new master cylinder if it's not compatible with the new (year) valve. Check with your GM parts dealer. They'll help you select the proper valve and master to match the 9 bolt you select.

There are a few posts on this site about the + and - of the 82-88 and the 89-92 9 bolts. Just depends on the which side of the brake fence you sit. I swapped an 87 9 bolt into my 91 RS and have no gripes. However, if and when I do this swap again, I'll swap in a 10 bolt disk.

Here's a link to a site that sells complete rear ends, for your information.
http://www.tacreationsusa.com

Good luck

 

Thanks for the info . What year would I be looking at for a 10 bolt disc. I just thought that the 9 bolts were the only disc available them years 82-92.

 

10 bolt disk rear differentials were available in 82-92. 82-88's have 26 spline axles and 90-92's have the 28's. If you want one of these, go to the web site link I previously provided and look under the used rear differentials section. Note: some 10 bolt disk rears are Open and some are Limited slip.

 

The 10 bolt is significantly weaker than the 9 bolt, though. By the time you got a 10 bolt as strong as a 9 bolt, and put disc brakes on it, you'll have significantly more invested in the 10 bolt.

I did a 10 bolt in my car 3 years ago. Zexel-Torsen posi with 3.42s; new bearings throughout and set up by an expert. I've dragged the car several dozen times, and road raced it quite a bit, but always on street tires. The rearend began vibrating several thousand miles ago; it's on the way to the crapper.

I did a lot of research on it. 9 inch, 12 bolt, s-60, etc. Any of those options will cost in the neighborhood of 2 grand, a 9 bolt can be done for a grand, even with the more expensive, hard to find parts. There are new suppliers showing up all the time, too, so the parts are getting easier to come by.

The 9 inch, 12 bolt, or s-60 would surely be considerably stronger than the 9 bolt, but, at twice the price, I don't think they'd be twice as strong; especially on a car that runs street tires-only.

 

9 bolts rock, and with the TA girdles available now, tha may add some more strength to it. If disc brakes are a concern, it is extremely easy to convert the early moraine calipers to the 89+ PBR setup. The axles are held on by backing plates, not c-clips. Very easy to remove, and I would recommend going through the rearend anyway. I have a spare 9 bolt that I am going to convery from a 2 series to a 3 series carrier with some nice gears. They are awesome rearends, and much overlooked IMO. Good luck finding what you need, I don't think you'll have a hard time at all.

Will