9 bolt borg warner rear.

[1hotroc]

I have the Australian 9 bolt rear end in my 87 Iroc. I have Two questions. one- the rear disc brakes seem to be hardly working as well as the e- brake. I need a cost effective way to solve the problem, calipers were already replaced. Two- how do I find out what rear end gear ratio I have.

[MdFormula350]

http://www.thirdgen.org/newdesign/tech/techdb.shtml

have you tried new brake hoses?

might have some air and new bleeding also.

[1hotroc]

Md formula NO I have not replaced the hoses. But I,m sure it woud'nt hurt to do them. My question for you is what year is your car and do you have the same setup as me? And if so do your rear discs work the way there supposed to.

[Tonys_T/A]

is the rear the original one that came with the car? if not, you need the correct proportioning valve to go with it. You can also modify the stock valve to deliver more pressure to the rear. The brakes on the 9 bolt are a pain in the butt, takes a lot of bleeding to get them right. As for the e-brakes, it's probalby a cable problem. Try adjusting them. The cables may be broke, if thats the case, you're going to have a hard time finding new ones.

[1hotroc]

Thanks for the reply. I have replaced the cables, and adjusted the hell out of em. The brakes work when the car is on the lift along with the e-brake. It just does'nt have the brake power when the car is actually being driven. I am inclined to think that it is a hydraulic distribution problem. Maybe the proportioning valve like you said. But as far as the emergency brake function it is down right dangerous because it is nonexistant! HELP!

[Tonys_T/A]

Yeah, the brakes on the 9 bolt just plain suck ass. I don't know what to tell you beyond what I posted previously since I haven't gotten mine figured out yet!!

[1hotroc]

O.K> I'll do the trial and error method. If I have any success I will post it. Thanks. It goes like a basterd but you can't stop the damn thing! SLP race day 13.70 at 102.2 MPH bone stock short block with TPI setup. 5.7L L98.

[tom3]

Look in the console for a white sticker with lots of numbers on it. Looking for codes that start with G. The G80 is for positraction and the other G will indicate the ratio. Do a search for Chevrolet RPO on Google and you can decode all those if you want. Lots of those nine bolts were airplane gears, like a 2.47 to 1, and better gears are hard to come by for that member.

[Tonys_T/A]

The majority were 2.77's, the rest were 3.27's which aren't too hard to find and there were a few 3.42's made. Aftermarket gears are available, but only from a couple companies. Strange makes a 3.70 gear, but it's expensive, and you can get other ratios from 9bolt.com

You can also check out 9bolt.com for any info on your brakes.

[1987irocz]

My iroc has the 3.45 rear end gears in the nine bolt. I believe it is part of the G92 option.

[1hotroc]

Is there any way to tell the rear by any castings on the housing. I'm going to look at a used Borg 9 bolt. The guy says it is a 3.27 Posi but how do I know he's not lying. Anybody know?

[MdFormula350]

i emailed u back with what i know, just a few more links to look at.