7.5 rearend Limits

[j0eyabs]

How much rearwheel horse power can a 7.5" rearend withstand?

[SVO-SMITTY]

I'm not sure, but I made 250.3rwhp and 325.3tq before I added my t3/t4, bigger fuel pump, head work and bigger cam. About 2months after I added the aforementioned, I busted my rear. Maybe someone else may have a better answer.

[NO 5 OH]

Re: 7.5 rearend Limits

Originally posted by j0eyabs
How much rearwheel horse power can a 7.5" rearend withstand?

Not much at all for sure

I had my car dynoed several months ago, and through the stock exhuast with some minor bolt on stuff it made 230 hp and 306 ft-lbs torque. This was on the stock T3 at 21 psi, running 100 octane unleaded fuel. I added a 3" downpipe off turbo, 3" to 2 1/2" y-pipe, and 2 1/2" Magnaflow catback and with a 275/50-15 Nitto drag radial it took six teeth off the ring gear while doing a little "test and tune." If you're gonna get serious with horsepower then it's your best bet to get an 8.8 and put it in. I didn't think that such little horsepower would break it either... but it'll go for sure. The only question is when.

[Pat_in_L.A.]

Differential

My bone stock 84 spit it's side gears out at 91k miles. I was just backling it out of a parking space at the market, not dumping the clutch or anything like that.

I ended up putting in a T-Bird 8.8 with 3.55's and an Auburn diff.

I consider the shock loads of dumping the clutch to be more of a factor in differential longevity than whatever the horsepower is.

[DON86SVO]

How much torque it can take depends on what you are doing with the car. When we first built our fairmont drag car we yoused a 7.5 rear because it was already in the car. We welded the spider gears and changed to a 4.10 ratio. It lasted 6 passes behind a stock lightning motor with a toploader 4-speed. The shock loads are tremendous on the starting line. If you are talking street use and occasional road course it will probably last longer.
BTW the car hooked up so good it lifted the front wheels about 8 inches and carried them all the way thru first gear.

[j0eyabs]

pretty much its a street car with occasional runs at sears point and laguna secca, no drag racing. I probably wont go over 300hp at the wheels.

[svooom]

I broke teeth off my ring gear at 47k and had the posi clutches replaced when the repairs were done. The guy at my local speed shop said that I'll be back in a few years to do it all again. He said that the 7.5 has a better posi unit than the 8.8 but isn't nearly as durable. I don't want to bastardize my svo with 5.0 parts but I'm not looking forward to dropping $300 every few years either

[j0eyabs]

ok well i was just wondering. my svo has 106000 miles and i have done no rear end work to it but i was wondering if it could handle 300 rwhp when i get there, i only got about 230 now so i got a long was to go.