I currently have a 10 bolt with 2.73 gears and open carrier and drum brakes. I have found a 9 bolt with 2.77 gears and posi-traction and disc complete with e/brake cables for 125.00. and I have also found an 86 iroc with a 10 bolt 3.23 gears and disc brakes for the same price for the rear end. I was just wondering what the opinion was on which one i should go with and also will i need the proportioning valve off of the iroc. Thanks for the help.

 

323 Iroc 10 bolt, add a girdle. And the valve. Assumming the Iroc has a posi. Even if it doesn't, it's going to be cheaper to build.

 

Go with the 9-bolt 2:77 rear, a better disc brake set up then the
10-bolt 86 disc's. The 9 is a stronger rear all around even if it is a 2:77.

 

I have an RS that I did the swap on. I went with the 3.23 10 bolt, disc, posi. It is cheaper and easier to get a ring and pinion for. I am very happy with it. I also have a 9 bolt in my T/A and I really like it. However I priced a new ring and pinion and carrier for this car and it was 900 just for the parts!!!. My best advice would be to find a 9 bolt if possible because it is better and stronger, but, only if you can find a 3.45 or maybe a 3.27. That way, you will not have to worry about a gear swap. If you can't find one, then definitley get the 10 bolt instead of settling on 2.77's!

 

get the 10 bolt. unless you wanna pay 125 for the 9 bolt, 450 for a new 3 series carrier, and damn near 300 for a set of gears. thats about 875 for the nine bolt (not including bearings & seals), unless you want to keep the 2.77 gears

the 10 bolt already has the 3 series carrier and 3.23s, and if you wanted steeper gears it would be about 180 for anything from 3.42 to 4.56, plus you can find parts for this rear everywhere you look.

9 bolts arent that great, if you were that geared on performance, the cost of a 9 inch or 12 bolt wouldnt matter.

 

Like I said...Only difference is that if he can find a decent 9 bolt in a 3 series, for that same price($125), then that would be the better choice. Of course the 2.77's are out of the question for the cost of the upgrade, but, if he can get a 3.27 or 3.45 9 bolt, as long as he changes the fluid and limited slip additive, than he'd be set for life. I have both rearends, and the 10 bolt whines some. If he can't find one for that price, or doesn't wanna waste the effort to look, then the 10 bolt is the natural choice of course. GM never should have produced anything below 3.23 anyway in these cars if you ask me!

 

I have 9 bolt gear sets up to 4.10 ratio and series 3 posi carriers available for 695. All the information is at www.9bolt.com

Miles
www.9bolt.com

 

is that with the install kits and all misc items seals etc? Also, is your stuff genuine GM or Borg Warner, or is it an aftermarket comapny? The reason I ask is that I if I have 2.77's(I think I have 3.27's just got the car), then I'd be interested as long as it wasn't some Taiwan brand stuff.

 

With the install kit, the total is 795. The only thing not included is axles seals, axle bearings and diff lube .

Borg Warner made the parts for GM. These parts are made on the same tooling that made the parts for GM ie it's OEM quality, no more - no less.

The other stuff coming out I manufacture.

Miles
www.9bolt.com

 

Thanks for for everyones input. I am not sure what i am going to do. I checked with a couple of places to day on a 93 up rear end and wheels (750.00with regular z28 wheels or 1000.00 with 98 up wheels) that would be with 3.42 gears posi and disc brakes. and i am still not sure which proportioning valve i need, or if i should just go with an adjustable one. I had a 9 inch ford almost ready to go with 3.50 gears and posi and disc but it burned up in my shop along with my tools.

 

"And a valve."

cp87gta: What valve???? Where is it? What is it? My rear could be going out and could use all the help it can get...what exactly are you referring to??? TIA

Also, how do you know if the posi clutch disks are worn out? Are there such things (thought I read about it somewhere, but can't remember for sure)? It's a limited slip and feels mostly like slip now, but it'll still fishtail. Any other thoughts??????

 

The proportioning valve is located under the master cyclinder[usually silver in color] . All of the brake lines go into this piece. Auburn posis don't have clutches, so if you have an auburn and it's worn out, you have to replace it. Not sure about the 9 bolt. I just sold a 345 9 bolt, didn't look at it very well. I went with the 10 bolt because of gear selection. Eaton posis are rebuildable, and new they can be bought for less than 350.00, on line.