need help with selecting rear end
need help with selecting rear end
I have a 1988 trans am gta and I am putting a pontiac 400 and turbo 400 trans in the car and was wondering about rear end choices that can handle 500 bhp. I also dont want to have to spend 2 grand for a new performance rear end I am kind of on a budget now.
Joined: Jul 1999
Posts: 10,950
Likes: 26
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: need help with selecting rear end
Your only choice then is the Borg Warner 9-bolt rear end that came in 85-89 Pontiac Trans Ams, and 87-89 Chevy Camaro IROCZ's. Most of them will be 2.77 ratio as they're the least desireable. Other ratios out there are 3.27, 3.45, and 3.70. A new 9-inch or 12-bolt will be $2000+.
Joined: Sep 2004
Posts: 2,777
Likes: 7
From: Casselberry, FLA
Car: 88 V6 'bird/89TBI bird/85 T/A
Engine: 2.8/TBI/TPI
Transmission: V8 T-5/700R4 x2
Axle/Gears: 3.42 open/2.73 open/ 3.27 9 bolt
Re: need help with selecting rear end
Do a search for "Magilla" in the engine swap forum. He ran an 11 second 1/4 mile in an 87 Trans Am. He had a 455 Buick under the hood. His recommendation was to use genuine GM ring and pinion and the newer 28 spline axles. He would break a stock axle shaft every once in a while.
Now you can buy the excellent replacement 28 spline axle shafts from Summit for 230 bucks!
So, you need...
1. A complete rear end from a car that had 28 spline axle shafts (I don't think yours has them)
2. A set of 230 dollar summit racing axle shafts
You could just change the side gears with the ones you need for the 28 spline axles and put them in your differential. I wouldn't do it unless you are willing to "qualify" all of your rear end internals and then set them up properly. Lots of people are a little scared of this process so I would just swap the assembly if you are unsure of your talents...
If you go hunting for rare rear ends, the 9 bolt is good and so is the Dana 44 from the Turbo T/A and the Firehawk cars. If a rich uncle dies and leaves you some money then you need to pony up and buy the Strange S60 Dana 60 that is made to drop in to our cars!
Good luck!
Now you can buy the excellent replacement 28 spline axle shafts from Summit for 230 bucks!
So, you need...
1. A complete rear end from a car that had 28 spline axle shafts (I don't think yours has them)
2. A set of 230 dollar summit racing axle shafts
You could just change the side gears with the ones you need for the 28 spline axles and put them in your differential. I wouldn't do it unless you are willing to "qualify" all of your rear end internals and then set them up properly. Lots of people are a little scared of this process so I would just swap the assembly if you are unsure of your talents...
If you go hunting for rare rear ends, the 9 bolt is good and so is the Dana 44 from the Turbo T/A and the Firehawk cars. If a rich uncle dies and leaves you some money then you need to pony up and buy the Strange S60 Dana 60 that is made to drop in to our cars!
Good luck!
Last edited by KrisW; Aug 15, 2007 at 12:00 PM.
Joined: Nov 2000
Posts: 1,022
Likes: 0
From: Newington, CT
Car: 88 IROC
Engine: 5.7 RamJet
Transmission: T56
Axle/Gears: Dana44 4.10
Re: need help with selecting rear end
The Dana was not an option on TTA's. They got the regular old 9 bolt. Only the Firehawks were delivered with the Dana 44. It was however something that could be ordered over the GM parts counter, or a dealer installed option for just about any thirdgen. It was also sometimes used as a service replacement rear for the 9 bolt rather than using a 9 bolt replacement.
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