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4th Gen rear questions

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Old Nov 17, 2009 | 11:12 AM
  #1  
adore's Avatar
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4th Gen rear questions

I have a 1987 gta with a t5 and and a posi diff..But its Been stored for almost 20yrs. I plan to install a aluminum drive shaft and maybe a 4th gen rear for 2 reasons: I want the 2inch width extra and mine needs a complete rebuilt. The question I have is regarding brakes, would I need all the brakes, bearing from a 4th gen?? Also what should I look for as far as gears?? I want low gears maybe something like my stock 3.45..

Thanks in advance guys!
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Old Nov 17, 2009 | 11:52 AM
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Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: 4th Gen rear questions

Its easier to find a 4th gen rear with brakes than to mess with trying to adapt 9 bolt brakes to the 4th gen rear. I'm not sure whats involved with that or if its even possible but 4th gen brakes from 98-02 are better anyway.

Those rears can be found with 3.23 or 3.42 gears but some 2.73's out there. Manual cars got 3.42's I believe but may have some auto cars with 3.42's.

Find one for 3 channel non traction control rear as it will have the proper brake lines on the rear to bolt to the factory hardline on your GTA.
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Old Nov 17, 2009 | 12:18 PM
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Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: 4th Gen rear questions

The following FAQ concerning 10-bolts (3rd and 4th gen) may provide some food for thought:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC
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Old Nov 17, 2009 | 12:40 PM
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Re: 4th Gen rear questions

Originally Posted by JamesC
The following FAQ concerning 10-bolts (3rd and 4th gen) may provide some food for thought:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

Thanks, but didn't find anything related to my conversion
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Old Nov 17, 2009 | 12:42 PM
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Re: 4th Gen rear questions

Originally Posted by Orr89RocZ
Its easier to find a 4th gen rear with brakes than to mess with trying to adapt 9 bolt brakes to the 4th gen rear. I'm not sure whats involved with that or if its even possible but 4th gen brakes from 98-02 are better anyway.

Those rears can be found with 3.23 or 3.42 gears but some 2.73's out there. Manual cars got 3.42's I believe but may have some auto cars with 3.42's.

Find one for 3 channel non traction control rear as it will have the proper brake lines on the rear to bolt to the factory hardline on your GTA.
What do you mean 3 chanel??

i was looking at buying something like this.
http://cgi.ebay.com/ebaymotors/98-02...Q5fAccessories

Last edited by adore; Nov 17, 2009 at 12:45 PM.
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Old Nov 17, 2009 | 01:17 PM
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From: Huntsville, AL
Car: 87 GTA, 88 GTA, 92 TA, 72 RS SS
Engine: 350, 350, 305, 396
Transmission: T56, 700r4, 700r4, T56
Axle/Gears: 3.42, 3.23, 3.23, 3.73
Re: 4th Gen rear questions

3 channel was for 4th gen cars with ABS only, 4 channel were for cars with ABS and traction control option. 3 channel rears have a ABS sensor on top of the differential housing above the ring gear, 4 channel rears have an ABS sensor on each end of the rear axle.
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Old Nov 17, 2009 | 01:37 PM
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Car: 80 SE/TTA;88 T/A GTA;86 T/A
Engine: 4.9L Turbo; LT1; empty
Transmission: TH350; T56; empty
Axle/Gears: 3:23 disk; 4:10 disk ; 3.42 disk
Re: 4th Gen rear questions

And what 3 channel really means, is that off of the proportioning valve, there are three channels, left front, right front, and 1 rear. 4 channel is left front, right front, left rear, and right rear. 3rd gen cars are 3 channel cars, and as such, a 4th gen 3 channel rear axle will bolt right in. You can even go so far as to use the rear rubber line off the 4th gen axle, and bolt it directly to your rear brake line on the body with no modifications.

Don't get it wrong though, if you were to find an outstanding deal on a 4 channel rear axle, take it, as you can adapt the axle into a 3 channel simply by running two brake lines, one from each side of the axle, to meet the t-brake line fitting in the middle of the axle.
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Old Nov 17, 2009 | 01:44 PM
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Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: 4th Gen rear questions

Originally Posted by adore
Thanks, but didn't find anything related to my conversion
The master cylinder, proportioning valve, and e-brake cables are usually concerns associated with a fourthgen swap (or thirdgen for that matter). Besides info on the aforementioned, there's also a link in the FAQ which provides T-5 drive and driven gear info that you'll require if you swap rear gear ratios.

JamesC

Last edited by JamesC; Nov 17, 2009 at 02:12 PM.
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Old Nov 17, 2009 | 02:06 PM
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From: Huntsville, AL
Car: 87 GTA, 88 GTA, 92 TA, 72 RS SS
Engine: 350, 350, 305, 396
Transmission: T56, 700r4, 700r4, T56
Axle/Gears: 3.42, 3.23, 3.23, 3.73
Re: 4th Gen rear questions

This should help you:

http://www.funkz.net/firebird/rearendfaq.htm
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