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rear diff. swap from 96 camaro to 91 firebird

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Old Oct 29, 2008 | 09:34 PM
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rear diff. swap from 96 camaro to 91 firebird

Hey guys I just got a rear disc posi of a 96 camaro 3800 seriesII v6 and im putting it in my 91 firebird. I wanted to know if any one had an idea what kinda power i can put to this rear end? and if i might have any brakeing problems because my rear end right now is drum and swaping it to disc.
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Old Oct 31, 2008 | 09:18 AM
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Re: rear diff. swap from 96 camaro to 91 firebird

im not sure about the power you can get but i do know u will need to switch proportion valve for it. i wanted to put a 87 disk rear in mine but i would have had to change mastercy all the way back. also the forth gen rear is 4inch wider also,




also this post prob should have gone into the susp.
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Old Nov 1, 2008 | 08:45 PM
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Car: 1991 Pontiac Firebird
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Transmission: blew trans up....T56 on the way
Axle/Gears: 9 bolt 3:45's >:)
Re: rear diff. swap from 96 camaro to 91 firebird

oh sorry I didnt know were to post lol......wait.. the proportion valve?..what exactly is that?
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Old Nov 1, 2008 | 09:24 PM
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Car: 1988 SC Convertible
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Re: rear diff. swap from 96 camaro to 91 firebird

Originally Posted by 91FirebirdAlex
oh sorry I didnt know were to post lol......wait.. the proportion valve?..what exactly is that?
Since you have a 91, there's no reason to change the prop valve. My car was originally a drum rear, but I swapped to disk. I never changed the prop valve and everything works great.
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Old Nov 1, 2008 | 09:27 PM
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Car: 91 camaro RS, 87 T/A
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Axle/Gears: 4th Gen 3.42/BW 3.45
Re: rear diff. swap from 96 camaro to 91 firebird

Originally Posted by FYRCHKN
Since you have a 91, there's no reason to change the prop valve. My car was originally a drum rear, but I swapped to disk. I never changed the prop valve and everything works great.

The prop valves are different, but some people say to change it, and others dont. I Had a pull on mine and i swapped the prop valve and it went away. As for the power, its pretty much the same as a stock 3rd gen 10 bolt.
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Old Nov 1, 2008 | 10:24 PM
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Re: rear diff. swap from 96 camaro to 91 firebird

Originally Posted by 91FirebirdAlex
Hey guys I just got a rear disc posi of a 96 camaro 3800 seriesII v6 and im putting it in my 91 firebird. I wanted to know if any one had an idea what kinda power i can put to this rear end? and if i might have any brakeing problems because my rear end right now is drum and swaping it to disc.

96 i believe came with the torsen worm gear differential i believe. which is good for a daily driver, but it wont hold up very well to track duty or any kind of racing, its also 4inches wider, also going from drum to disc, your gonna wanna grab the proportioning valve. its better to be safe than sorry, but sometimes it causes problems such as excessive brake pad wear. so id say just ****** it
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Old Nov 3, 2008 | 12:01 AM
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From: Peoria,Az
Car: 1991 Pontiac Firebird
Engine: Carbed LQ4 6.0
Transmission: blew trans up....T56 on the way
Axle/Gears: 9 bolt 3:45's >:)
Re: rear diff. swap from 96 camaro to 91 firebird

cool, thats good to hear....thanks guys..youve been a real good help.
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Old Nov 4, 2008 | 11:30 PM
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Car: 91 camaro RS, 87 T/A
Engine: 350 TBI, 305 TPI
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Axle/Gears: 4th Gen 3.42/BW 3.45
Re: rear diff. swap from 96 camaro to 91 firebird

Torsen was 98 and up im almost positive. It came out the first year of the LS1 didnt it? and the tires dont stick out too much so dont be alarmed by that.
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Old Nov 5, 2008 | 09:11 AM
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Re: rear diff. swap from 96 camaro to 91 firebird

Originally Posted by FYRCHKN
Since you have a 91, there's no reason to change the prop valve. My car was originally a drum rear, but I swapped to disk. I never changed the prop valve and everything works great.
It may work, but your not getting the full stopping power of the rear disk with a disk/drum prop valve. What's the point of swapping in disks if your not gonna use them to there full potential? Do it right and get a disk/disk prop valve. On my 91, when I did a 4th gen rear swap, I bought a 1LE prop valve and used a LS1 master cylinder.

The 96 rear has the Auburn diff, the one with the clutch packs. And the 96 rear can handle the same power handling capabilities as your stock rear.

There are plenty of threads on this already. look in the Transmisson/Drivetrain section. Or even better, just try searching "4th gen rear swap".

You will also have to change the speedometer gears in the tranny, unless the 4th gen rear is the same gear ratio as the one on your car now.
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Old Nov 5, 2008 | 03:36 PM
  #10  
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Car: 86 Camaro iroc-z28
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Re: rear diff. swap from 96 camaro to 91 firebird

Originally Posted by krisb410
It may work, but your not getting the full stopping power of the rear disk with a disk/drum prop valve. What's the point of swapping in disks if your not gonna use them to there full potential? Do it right and get a disk/disk prop valve. On my 91, when I did a 4th gen rear swap, I bought a 1LE prop valve and used a LS1 master cylinder.

The 96 rear has the Auburn diff, the one with the clutch packs. And the 96 rear can handle the same power handling capabilities as your stock rear.

There are plenty of threads on this already. look in the Transmisson/Drivetrain section. Or even better, just try searching "4th gen rear swap".

You will also have to change the speedometer gears in the tranny, unless the 4th gen rear is the same gear ratio as the one on your car now.

was it till 98 then that the zexel diff came out ?
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Old Nov 5, 2008 | 06:30 PM
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From: Peoria,Az
Car: 1991 Pontiac Firebird
Engine: Carbed LQ4 6.0
Transmission: blew trans up....T56 on the way
Axle/Gears: 9 bolt 3:45's >:)
Re: rear diff. swap from 96 camaro to 91 firebird

I have a buddy that has a 4th gen diff in his 3rd gen camaro...3:73 gears and he didnt swap the valve and he has no breaking problems...unless there is something he hasnt noticet. and you guys say that the 4ths rear handles the same power as my stock one?...i have a stock 5.0 tbi in my bird..and its off a 3800 series..I dont know...i heard there good up to about 200+ horse power but im not too sure....
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Old Feb 10, 2009 | 03:50 PM
  #12  
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Re: rear diff. swap from 96 camaro to 91 firebird

Does anyone have any pics of a 3rd gen Camaro, with a 4th gen Rear axle? I keep hearing that they are so much wider, how does it look?
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Old Feb 10, 2009 | 05:55 PM
  #13  
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From: Tampa/New Hampshire
Car: 91 camaro RS, 87 T/A
Engine: 350 TBI, 305 TPI
Transmission: 700r4
Axle/Gears: 4th Gen 3.42/BW 3.45
Re: rear diff. swap from 96 camaro to 91 firebird

I post up pics all the time of my car for people cause the hardest thing ever is to use the search feature. But sadly i already posted a pic today and i dont feel like posting again, head over to the driveline forum its about 10 posts down.
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Old Feb 10, 2009 | 09:55 PM
  #14  
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Car: 1991 Pontiac Firebird
Engine: Carbed LQ4 6.0
Transmission: blew trans up....T56 on the way
Axle/Gears: 9 bolt 3:45's >:)
Re: rear diff. swap from 96 camaro to 91 firebird

here are pictures before and after the rear end went in.


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the 4rth gen rear ends do stick out a bit..but i think it gives it a more agressive look.
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Old Feb 10, 2009 | 10:04 PM
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Car: 91 camaro RS, 87 T/A
Engine: 350 TBI, 305 TPI
Transmission: 700r4
Axle/Gears: 4th Gen 3.42/BW 3.45
Re: rear diff. swap from 96 camaro to 91 firebird

Originally Posted by 91FirebirdAlex

the 4rth gen rear ends do stick out a bit..but i think it gives it a more agressive look.
I agree my car looks mean as hell since i put the new rear in. Especially lowered.
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Old Feb 16, 2009 | 02:24 PM
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Re: rear diff. swap from 96 camaro to 91 firebird

Has anyone ever cut an inch or so out of the 4th gen rear end before they install it. I'm mean you'd have to get new axles that are the correct length, but if the width is a problem that should solve it. Depends on how much axles are though I guess.
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Old Feb 16, 2009 | 02:35 PM
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Re: rear diff. swap from 96 camaro to 91 firebird

Am I the only one that's fairly certain that any rear end from a V6 camaro doesn't have a posi at all?? Not sure why you guys are all talking about Torsens and whatnot.
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Old Feb 16, 2009 | 02:39 PM
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Re: rear diff. swap from 96 camaro to 91 firebird

Double Post

Last edited by Calaban007; Feb 16, 2009 at 02:46 PM.
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Old Feb 16, 2009 | 02:45 PM
  #19  
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From: North Carolina
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Re: rear diff. swap from 96 camaro to 91 firebird

There were some 4th gens with the 3800 that had a performance package, Y87, I believe was the RPO code. The had positive rear ends. I don't know how many were made though.
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Old Apr 21, 2009 | 12:17 PM
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Re: rear diff. swap from 96 camaro to 91 firebird

Originally Posted by 91FirebirdAlex
here are pictures before and after the rear end went in.







the 4rth gen rear ends do stick out a bit..but i think it gives it a more aggressive look.
Stock 3rd gen rear wheels on a 4th gen axle do SET out farther, but not STICK OUT. "Stick out" implies past the fender lips. They do not. I wish people would stop perpetuating that MYTH.

The tires will still under under the outermost portion of the fender lip. Not end up like reverse offset, spoked lowrider wheels.
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