My 1991 GTA is a one wheel wonder. GRR. Either the limited slip is worn or doesn't exist.

I do, however, have 3:23s from the factory, so I can't complain.

I can get a good deal on a 9 bolt 2:77 posi rear with disc brakes. Is it possible to take the posi out of that rear and put it in my car, ye3t keep the 3:23s (I dont even know what conditon the rear is on or what year/car its off of yet) I'm not sure how many miles are on the rear either. Do high mileage rear ends tend to give out?

Thanks guys!
Bill

 

you'd prolly be better off putting a powertrax unit in your current differential,yhe 9 bolt gear swap will cost a bunch,plus i believe the only one available is the 3.90.
7.5" 10 bolts are still a dime a dozen

 

your gears and carrier will not interchange

 

Sleeper, thanks for the fast response! Unfortunately, I'm not too savy with differentials.

I dont mind changing the gear ratio. I want my car to be street/track with the occasional drag strip. Is 3:23 optimal for this, or do I want something bigger?

I'm not sure what my current differential is. (9 bolt, 10 bolt, etc)

What exactly is a powertrax unit, and where can I find one for the best price?

Do I probably have a 10 bolt? Or are you suggesting I do a 9 bolt swap?

Sorry for all the questions.

Thanks!
Bill

 

Your car probally has a 10 bolt just crawl under the car and count how many bolts are on the cover. I hear the 9 bolts are a lil better then the 10 bolts but they are really hard to find parts for. Im in the same boat as you my car all of a sudden is a one wheel wonder. Im probally gonna go with an auburn limited slip unit and swap out my 3.23's for some 3.42's since im in there. Where in jersey you from ?

 

I'm in Whippany, NJ half of the year (near Parsippany) and in New Brunswick the other half. Are you from NJ? I've been looking for some fellow third genners to play with

Should I go Auburn or Powertrax? How about gearing?

 

Another thread mentioned zexel, torsen, and truetrac. They also said the powertrax unit is a locker, therefore no good for street/track.

 

Yeah im from Jersey, Wayne area. The zexel torsen units were from slp and i don't think they sell them anymore some one correct me if im wrong. For street/ some track people on here say go with 3.42's if you have tpi. What track do you goto ?

 

I haven't raced at a track yet. I just got my GTA this summer. My daily driver Honda civic is all I had before then. Now that the weather is clearing up, I want to start racing. I'm a total noob, so I've got a lot to learn.

If you want to meet up sometime, let me know! The Willobrook mall is about a half hour away from Whippany.

Can anyone second that 3:42s are optimal for street/track use? I will be upgrading the engine, possibly an LSx swap in the future. Is that gear ratio still good?

 

I go to island drag you get more runs there compared to english town where you only get 3 and sometimes only 2.

 

Why not go that high with a TPI?

 

ha edited my other post instead of making a new one owell tpi stops making power around 4500 rpms and with 4.10s you would be in the higher rpms faster and all your power is in the lower rpms. Im no expert on it someone else could probally explain it better. Check out NJfboa.org if your into going to car meets with just fbodies they have alot of meets and i think they meet at willowbrook sometimes also

 

I wouldn't go much lower (numerically higher) than a 3:23 with a stock TPI setup.

EDIT: I meant stock 5.7 TPI.

When I got my Trans Am it had a stock LG-4 305 that just flat out quit making power at 4500 rpm. I was going to install my 355 soon, and went ahead and installed a 3.73 gear and a posi. It behaved like a completely different car, and the motor launched harder, reached its shift points much quicker, and fell flat on its face quicker than with the 2.73's that were in it stock.

If you are planning other mods down the road like at least porting or changing the intake, and headers/exhaust, then a 3.42 would be a great all round gear for street and race, and a 2500-3000 rpm converter would help out on the bottom end.

Just my

 

Allright, it's looking like I'm sticking with my 3:23s for now.

If I change my rear to a posi, will I be able to keep my 3:23s? What if I want to upgrade down the road, will I need a whole new posi?

I've heard some good things about zexel-torsen, and truetrac. Any input?

If I put the $$$ into the rearend, is this something I would want to keep when I get to an LSx swap down the road? Or is this money thrown away

Thanks again!
Bill

P.S. 91 z28 350, I've never heard of Island Drag. Where's that located? Please tell me it's closer than Englishtown!