Hello, I have a 1986 Trans Am. I am currently undergoing a 383 build to swap in it this winter. The power levels are going to be roughly 400 horsepower. The stock 700R4 is gonna get a shift kit and a corvette servo. The thing I'm worried about is the stock 10 bolt. I've heard these things aren't very strong. I take this car to the strip every once in and while. The stall is the stock low stall 1500 ish converter. I also do have some Nitto N555Rs for slicks. I'm wondering if the 10 bolt will hold up to the power with a stock stall? And if the thing blows, what would be considered for a replacement? I don't want to spend the money for a Mosier 9 inch or something like that. I've heard to grab a rear end out of a 90-92 firebird/Camaro. Because they are 28 spline axles and all limited slips. I don't know if this is true but if so great.

Thanks, Sean

 

For the power level you have now, you'll be fine.
The low stall converter will help not to break your diff.

For replacement, don't put in the same diff, unless you want it to break again.

You can build up the stock gm 10 bolt, with little money , weld axle tubes and get a girdle.

If you want to go fast, you gotta spend the cash...

 

OK. Glad to know the diff is good for now with the stall. If it does go I might step up to a 8.5 10 bolt but I don't want to think about that right now lol

 

Diff may be ok for a bit if the tires aren't sticky. Especially if it's a clapped Auburn posi - probably won't lockup hard enough to break anything. Might break an axle shaft though if you get it to hook with that much power.

But you'll blow the "stock" 700 to bits. No question. Especially the older unit without the aux valve body. Shift kit and servo won't help it any. It's just not going to be strong enough without upgrades.

GD

 

Ok. I was thinking that lol. But I'll keep that in mind. I'm basically running her till she blows

 

whats the significance of your username? 9sinteh86TA. 1/8th mile ? is is 9's your hopeful 1/4 mile goal of the car's build?

 

1/8th mile for sure. It's just a pretty low standard goal. But the track I go to requires your car to run faster than 10 to be able to get into some classes. So the goal is to break into the 9s in the 1/8th

 

Stock tpi cars are in 9’s in 1/8. Thats easy

 

Yeah, I think mine lost a couple of horses out the pipes after 34 years. She ran 10.11 last time. Set your goals lower and lower till you achieve them lol.

 

ah, gotcha. I was initially thinking that your username had something to do with wanting to one day run 9s in the quarter. yes, a nice mid-high 9 second 8th mile time is on par with what a "normal" TPI setup will do and with what your goal/plan for the rear end is. gotcha. good stuff.

 

Yup. The main goal is to beat a buddy of mine. I've heard nothing but trash talk from him all year lol and I've had enough. His car is a 1994 Chevy Caprice. Lt1 motor. Stock with longtubes. 4.10 gears and a locker in his 10 bolt. Ran 9.44 before the 4.10 swap. Had 3.08s
​​Any realistic hope of beating him? And if not nitrous sounds like a plan

 

It gets expensive to run 9's in the 1/4. I know my car has an 8 second pass in it if I can ever get back to the track. It's a 100% drag car and not street legal.

 

Yeah maybe eventually I'll get there lol. But for now I got to drive it to school so I'll keep her loud and that'll be good enough

 

Welp, Ive made the discovery of my rear end today. I realized that its a 9 bolt Borg and Warner so I don't think the diff will be the weak link anymore.

 

The 9 bolt will hold up - get a Torsen from Australia, some 3.70 gears and a girdle cover for it.

Stock ratio on the 86 TPI Trans Am WS6 with the 9 bolt is 2.77 - terrible gear ratio.

GD

 

My bone stock 91 305 auto car ran 9.40s in the 1/8 mile so your 383 should get you where you want for sure.

 

No wonder it's so sluggish

 

Well there I go. Maybe 8s then

 

I got my stock 7.625 gm bolt with slicks to a 7.0 in the 1/8th(11.0 in the 1/4), for 2 runs, then it blew.
I welded the axle tubes and had a girdle, stock axles.

Ticking time bomb...

 

j7.0 is smokin.i don't think I'll be that fast for awhile