So looking to make my rear end a limited slip w/ posi and change the gears to 3.73 or 4.10/4.11.


Car: 89 firebird
so this is a 27 or 28spline, 10 bolt 7.5" ?

looking at jegs for the gears it seems my car fits the above with the 27 spline, but then looking at jegs for the differential it looks liek i fit the above witht eh 28 spline.

I am now confused(ya i know its not surprising )


Thanks.

 

I'm pretty confident in teh 10 bolt 7.5 numbers, but this spine thign is confusing.

 

1989 was the change over year from 26 to 28 spline axle shafts. Only way to be sure is to pull them and count splines. Also this is a good time to check what rear you have (9-bolt or 10-bolt) and the series carrier 2 or 3. Remember, 10-bolt parts WILL NOT work on a 9-bolt rear.

 

And so if its a 26 spline then thats not good right? as I understand it the more splines the better?

So with the trans i'm having put in its cappale of handling upto 450 hp, I figure thats more than enough for my goals, but a rear end with a 26 spline isnt gonna be good for 300 or 350 rwhp right?

I know its an auto so that means 2.73 adn a 2 series?

 

In reply
If you have 26 spline axle shafts the problem may be finding parts.

The more splines the less backlash, which would mean stronger to you.

Correct a 2-series carrier. But you didn't say what the engine was? Ratio could be different.

Suggestion: Find a used rear which would fit your needs and junk what you have. Also this would be a good time to ugrade your rear brakes.

 

Thanks, engine is a 305, possibly not original. Used rear sounds liek a good Idea to me. Monday it goes in to have alot of work done so I'll add finding out the spline to it.

Never even thought about the brakes!