Lets play..Name..That...Rear!!!
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From: Buford, GA
Car: 89 RS
Engine: 6.3L Megasquirted HSR
Transmission: T56
Axle/Gears: 3.70 Posi 9 bolt
Lets play..Name..That...Rear!!!
So heres the deal. I got a 9 bolt from a guy that SAID it was out of an 86 IROC. Stock 3.70 posi, PBR discs, and from what I heard PBRs werent installed until 89. Well, I had to turn the rotors today at work and it turns out one of em needs to be replaced. Do I need to find out EXACTLY what year/model this rear came out of, or can I just ask for rear rotors from an 89? Does it matter if they are for a 9 or 10 bolt?
One more thing. Im still trying to figure out the prop. valve situation for the 10 bolt drum to 9 bolt disc swap. Are the PBRs part of the 1LE package? None of the GM parts guys I work with know what I should get. I still have the stock front brake setup for my 89 RS, so if it was part of the 1LE then I would have to change the front setup before I could get the 1LE prop valve correct?
One more thing. Im still trying to figure out the prop. valve situation for the 10 bolt drum to 9 bolt disc swap. Are the PBRs part of the 1LE package? None of the GM parts guys I work with know what I should get. I still have the stock front brake setup for my 89 RS, so if it was part of the 1LE then I would have to change the front setup before I could get the 1LE prop valve correct?
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Joined: Jul 1999
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From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
The housing can't be from 1986 since the 9 bolt wasn't offered until 1987 but the PBR disk brakes are only on a 9 bolt in 1989. No third gen came with 3.70 gears from the factory but they were easily available over the counter from GM.
You have a fabricated 1987-1989 diff that someone changed the gears and installed PBR brakes on or it's probably all 1989 stuff and someone just changed the gears.
You have a fabricated 1987-1989 diff that someone changed the gears and installed PBR brakes on or it's probably all 1989 stuff and someone just changed the gears.
Thread Starter
Senior Member
iTrader: (9)
Joined: Nov 2004
Posts: 996
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From: Buford, GA
Car: 89 RS
Engine: 6.3L Megasquirted HSR
Transmission: T56
Axle/Gears: 3.70 Posi 9 bolt
I thought I rememberd seeing a post on here saying that 3.70s were offered in the L69 "true H.O." cars? no biggie, just curious
So do the rotors have to be for a 9 bolt PBR or can they be for a 10 bolt PBR? I checked at autozone today and they wanted $90/rotor for the 9 bolt. I know that parts for these things aint cheap, I aint complainin. Just wondering what the differences are, if any, and possibly price differences.
So do the rotors have to be for a 9 bolt PBR or can they be for a 10 bolt PBR? I checked at autozone today and they wanted $90/rotor for the 9 bolt. I know that parts for these things aint cheap, I aint complainin. Just wondering what the differences are, if any, and possibly price differences.
Joined: Jul 1999
Posts: 10,950
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From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Yes, from what I have heard, the 86 Trans Ams with 5-speeds and L69 HO engine got the 3.70 9-bolt rear end.
If you were at autozone, why dont you have them look up the part numbers for an 89 rear end vs other years? Then you can see if a 10-bolt rear is different. I doubt they are different, as GM used the same rear brakes from 82-88 and then 89-92 is the "1LE" rear brakes. The 9-bolt years are 87-89 in Camaros and 85-89 in Firebirds.
If you were at autozone, why dont you have them look up the part numbers for an 89 rear end vs other years? Then you can see if a 10-bolt rear is different. I doubt they are different, as GM used the same rear brakes from 82-88 and then 89-92 is the "1LE" rear brakes. The 9-bolt years are 87-89 in Camaros and 85-89 in Firebirds.