I know someone somewhere has probably already answered these questions but I've searched and I cant find what I'm looking for. I am thinking about purchasing a rearend out of a 1995 Firebird to go in my 1986 Trans am. I know these rearends will swap out but I'm wondering what size this rearend is. Is it the 7.5, 7.625, 8.2? Also, does anyone know about what kind of gears it will have? I have the 2.73 ratio gear. Sorry for this post being so long but any help on this would be appreciated. Thanks!

 

Welcome to TGO. Most of your questions will probably be answered by the following sticky:

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

JamesC

 

for all intensive purposes, 7.5 and 7.625 are the same thing. The rear will be a 7.625/7.5 rear, and there is no way for me to tell you what gears are in it. Pull the cover off and count the teeth.

 

7.5, 7.62 either way its a small 10 bolt it could have anything from 2:73 to 3:42 just like third gens. If its out of a T/A or Formula it should be a 3:24. But hard to tell for sure. Remember 4th gen rears are 4 inchs wider over all so get ready for your tires to stick out or to buy new wheels

 

Like all 4th gen rear axle assemblies it is 10-bolt with a 7.625 dia gear. The ratio could be a 2:73, 3:23 or 3:42 these are the only stock ratios available.

 

ok thanks guys. only reason I'm thinking about getting the rearend is because I broke my 26 splined axle in my other rearend and I know this one should have 28 splined axles. Are the 28 splined axles that much better than the 26?

 

they are 2 splines better, they are still not a very strong rear.

 

Stock 3rd gen rear wheels WILL NOT STICK OUT. This false information is passed on time after time after time and several keeps pointing out the truth.

 

For the most part, all this is outlined in the sticky.

JamesC

 

I was not stating that the tires would stick out past the quarter panels. They "Stick out" further than the stock rear end. This gives the car an unbalanced look about it. the front of the car should be wider than the back which is why IROC's T/A's GTA's and such have wheels marked "Front" and "Rear". this wider rear end puts your tires closer to the inner quarter panel make it then more likely to rub during cornering or with a load in the car (I.E.Friends in the back seat). It does give the car a more agressive stance from the front and side, but with out a wider wheel and tire combo for the rear, from the rear it looks odd. I personally do not see any advantage to puting a 4th gen rear under a third gen unless you do go with a wider rear wheel. For handling purposes you want the front to be wider than the rear. But again for the average driver you propably would never see ant differance and it wouldnt matter anyway. So if anyone really wants one.....I have 3 or so lying around I'd be happy to sell you. I'd just put the brakes on the third gen rear and be done with it.(And yes I know that would take more time and effort)

 

Where do I start?

#1...Your wrong, about the "For handling purposes you want the front to be wider than the rear.".....Track widths are made narrower, by the factory, to cause the rear end of a car, to "fall in line" behind the front. It does NOT make a car handle "better". It merely makes it EASIER for your average driver to maintain control.

#2.....It does NOT look better, the way the factory set them up. How many times have you heard, from people who notice the shallower outside lip vs the deeper outer lip on the front wheels....."That just looks wrong....Looks like the rear wheels are narrower than the fronts." Have you ever seen a custom car, built with narrows in back, wider up front? OH YEAH......R I C E R S do that, for drag racing.

#3.....For handling purposes, you want all 4 to be equal, or the rears wider. Front being wider makes the car do things, that the (performance) driver has to fight.

#4....The wheels are marked that way, so people don't mount the rears on the fronts. Fronts fit rear, rear doesn't fit front.

#5.....Who goes to buy new wheels & gets deeper nackspacing for the rear? NOBODY! They buy all 4 to match. The wheel shop doesn't even make the suggestion that you do that.