I have the opportunity to get a rear end from an 84 Trans-Am... disc brakes and all. I was wondering is it posi too? And is it worth it?
I read that it is 3.23 discs.
I will also need to get my speedo recalibrated for it too...
I'm just wondering should I go through with it?
I'm just 2.73 drum open right now.
It is in good shape too.

 

if its not too much money, sure why not.

 

It's not too much money Tas.... I'm just wondering if the swap is a worthwhile one... I'm getting the whole rear axle with brakes for a great price. I am just thinking about the other work involved with replacing it. And would it be worth it in the long run to go from 2.73 to 3.23? I know having disc brakes are a good thing.
Those alone are worth what I'm paying for the whole rear axle. I am just thinking about the speedometer etc... would everything bolt right up to my 91 bird?
How much do I need to change?

 

i would say it is worth it.
1. discs are way better than drums, they look better too
2. a posi is worth grip and grip is worth et
3. 3.23 is a better gear tahn 2.72, gear is worth et

basically your car will be noticably quicker and a lot safer. you may even beable to get a few bucks knocked off your insurance if you tell them you upgraded to rear disc brakes.
sure you will knock more off your et with 3.42's or 3.73's in your car, but for the money and the total package you are getting teh 3.23's are a very good gain.

later
tim

 

If you wanted to you could always go to 3.42, 3.73s or whatever else who want to go to later if the 3.23s aren't cuttin it.

-Timbo-

 

Would it be a direct bolt on? Or will I need to do some modifications to make it all work? It appears it is, but has anyone done it?
I am saying about when the brakes are changed to discs, do I have to do anything with the master cylinder, or can I just use the existing lines for the discs?
And if that is all okay, I should be good to go?
What about the speedo? What will I need to recalibrate it?
I have a 91, I guess it's part computer/part cable?
I am unsure.

 

I think you would need to modify your brake proportioning valve. Drum brakes need a LOT less hydraulic pressure to operate (i.e stop the car) than disc brakes. So if you simply put disc brakes in the place of drum brakes, I don't think they would do very much without increasing the rear brake bias. This is something the 94-96 Caprice 9C1 guys do all the time because the Caprice 9C1 switched to rear discs in 94, but GM didn't change the proportioning valve, so the rear calipers sieze ALL the time because they're basically not being used. I think the bias is something like 95/5 on my car (rear drums) and 70/30 after the mod to the valve for discs...just something to chew on. It's not a hard mod, just drill a hole in a bolt.

 

I was editing my post just as you posted Kev. That was something I was concerned about too.

 

you can use the stock prop valve. when i did the road racing conversion i used teh stock proportioning block.
the housing is exactly the same, gm kept all teh mounting points exactly the same over teh whole generation.

later
tim

 

id say skip it

3.42/3.73 rears are a dime a dozen.. throw a power trax in and you are set. Who cares about rear disks unless you are road racing, drums are better for drag racing anyways

for me it was 65 bux for 3.42 rear out of junkyard
+ 315 for the powertrax to my door
a few bux for fluid and a few bux for a gasket

 

$315 for a limited slip? damn dude, that is a lot of money just to turn both tires. SLP take out $99, if you watch their site they put them on sale for $75 from time to time. SLP also sells speedo gears.
and how are drums better for drag racing? you can stall a car up against a convertor better with discs or if you want you can clearance them so they don't drag just liek drums. aluminum drums would save soem weight(6-10lbs per side dependign on which drums gm put on your car) but stock iron drums weigh the same as a rotor.
drums are also no risk to lower your insurance, unlike discs which most companies consider a safety feature and give a little discount for.

later
tim