Ok, so i have an 86 iroc with a standard 3.23 rear end with drum brakes. I want a posi rear with disk brakes. Is there a certain year that can bolt up to my car no problem and is it worth going to disk in the rear. What problems will i encounter and what do i need to do to make a successful swap. Any advice will be appreciated. thanks

 

any 3rd or 4th gen f body rear will be a direct bolt in

 

Welcome to the site.

Here's a couple of options:

1. Replace the rear with a posi disc rear from a '90-'02 F-body. The will all bolt in but you will have issues with the e-brake cables for the '98-up rears and the '93-up rears are a bit wider than the 3rd gens. This will be your cheapest option as you can get a whole rear for $200-300 and a gear install will cost that.

2. Keep your 3.23 and swap it over to discs. You will need disc backing plates and a rear disc setup from a '89-97 car, and install a take-off posi from SLP ($100).

Search a little and you'll get a load of info on the topic.

Ed

 

thanks guys, that the fastest i have ever seen any one reply.
One thing i wasnt really clear on in my question was is it worth the money to change from a drum rear to a disk rear. are the advantages that good.

 

Fellas, wasn't there two different rear-ends used on our thirdgens? I read somewhere that one was built in Australia and significantly weaker? When looking for a replacement how do you tell the two apart? Thanks

 

thirdgens came with 10 bolts, 9 bolts, and dana 44s. listed weakest to strongest and most common to most rare.

 

Thanks EDE, do you know where we can get a picture or description to tell them apart? Does the 10 bolt / 9bolt refer to bolts on the cover? I'm not sure what to look for to find the more desireable rear-ends. Sorry if I've taken over this post, but I think this will help a lot of us that are new to modding the thirdgen.

 

Yup you hit it right on the head.

9 bolt has 9 bolts and a circular flatish cover

10 bolt has 10 bolts and a circular flatish cover

I'm sure you won't run into a Dana 44 but...
I can't remember how many bolts, but the cover is not flat by any stretch of the means. its got a big hump on one side.

 

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the big bump is a magnet if you can get a 9 bolt do it immediatly gears are a hard thing to find for tho .Yes if will pop in but if its disc then you will have problems with the e-brake cables.


when buying a rearend from a yard put it on milk crates,jackstands,ect and spin the axel if the both spin the same way its a limited slip or "posi" if they dont then its open or "junk" unless its cheap and you have a posi unit for it.

As for telling what gear it is. Spin the axel one tim and count how many times the yoke spins.If it spins 3 1/2 times its 3.42 if 3 3/4 its 3.73 , 3 its 3.08 ect . it you lookin to make gobs of power out of this car i dont recomend a 10 bolt i am still infamiliar with these stupid rearends too...