I have a 91 Firebird Formula Automatic with stock 305 and TBI. I was just wondering what the advantages/disadvantages would be if i swapped the stock 2.73 rear end for a 3.42? A buddy of mine has an 85 camaro with the v6 and i was considering getting the rear end from him.

thanks

 

You will notice an increase in acceleration as long as you can keep traction, however without a posi there's no telling what will happen off the line. There's a chance you will notice a decrease in highway mileage, but it will probably be negligible.

As far as I know that rear end will be a direct swap. You are still going to have an open rear end and drum brakes. I would say it's only worth the work if you are getting the whole axle for free, or less than $50.

Keep in mind the 85 has 26 spline axles as oppose to the 91 having 28 spline. All this means is the 85 axle is slightly weaker, but with a stock 305 there is nothing to worry about. Just keep this in mind if you ever upgrade your engine significantly.

If it were me, I would save up another couple hundred or so and look for an axle out of a 98-02 Camaro. It's a *almost* a direct swap, but that way you can get 3.42 gears with a posi, as well as disk brakes, all in one package. It will probably run you at least a couple hundred however and it will be 2" wider each side so stock wheels will be pushed out that much.

 

what would i have to do to get the 4th gen rear end to hook up?

 

from my understanding, the e-brake cable will have to be modified to hook up and if u get a 4-channel rear (traction control?) u will have to install a t-fitting for the brakes to work, or just look for a 3-channel rear since it should have that t-fitting on it already. oh and a new proportioning valve for a disk/disk car is also highly recomended. a search should get you more/better answers

 

A 4 channel rear end or a 3 channel rear end will both work fine. 4 channel rear ends = traction control, 3 channel = no traction control. I put a 4 channel on mine, you leave one of the hardlines on the rear, then take your T-block and the other hard line from the 3rd gen drum rear. Search for posts made by me under Search > Advanced Search with keywords "4th gen rear installed".

What he said about he ebrake cable ^^^^ this is the hard part, since there is no direct-fit cable. You will have to come up with your own solution.