Hey Guys,
I just picked up a new 9-Bolt rear for my 1991 RS. I know almost nothing about the rear other than it came out of an 83, it has disc brakes & it has been sitting for a while. It comes with calipers, brake lines, and a few suspension parts. I will be paying $100 for the rear when I pick it up next week. I don’t know much about rears, but I need to check it out before I put it in my car. This is what I am planning on doing when I get it. I am going to clean it up, make sure the gears aren’t screwed up, make sure the calipers aren’t frozen, replace the brake lines, and put in new bearings, gaskets & fluids. And I will probably re-paint it for ascetics.

Now for the questions:

1) Am I forgetting anything? Is there anything else I should do before putting it in my car?
2) What differentials were put in the 9-Bolt in 83? I am hoping for either a 3.42 or 3.23 posi unit.
3) When I pick up the rear, what kinda things can I look for to let me know that this rear will be more trouble than its worth?


Thanks in Advance,
Mark B

 

Check the following link for a ton of info:

https://www.thirdgen.org/techbb2/sho...hreadid=239666

JamesC

 

Yep, lots of great info at that link James posted. Also, be a bit wary if you've been told it's an '83 9-bolt, because the 9-bolt wasn't offered in the thirdgens until '85. That doesn't mean it's not a 9-bolt because it could very possibly have been swapped into an '83 car at some point in time. If you pull the cover off the diff the gear ratio will be stamped on the edge of the ring gear. I'll attach a pic of mine (that I just got) which says 3 27 (hard to see in this pic, but visable when zoomed in). That link should pretty much answer all your questions though!

-Paul

 

When I got my 9 bolt I just marked the axle and rotated the pinion yoke around until the axle went around once. It went around about 3 and a quarter times so its a 3.27. Later when I opened It up I saw the stamp anyways. You can also divide the number of teeth on the ring gear by the number of teeth n the pinion gear. That will give you the ratio.

As far as wear goes, bring a magnet and check the oil with it to see if theres any sort of metal filings sitting in with the oil.