[valtiel43]

I have an 86 Cutlass with a built sbc 383 stroker in it. I'd estimate it makes around 450hp. The car has a beefed up transmission (or at least I was told it does). And unfortunately it's running the stock 7.5 rear end. I'm saving up money to put a Ford 9" in it soon. Until then stock has to do.

The problem. Sometimes when I take off from a dead stop I hear a weird kinda click or thud sound coming from around the tranny, driveshaft or rear end. It's not loud, and doesn't occur all the time. I know the rear end doesn't have much life left in it, but I hope it will hold up for at least a few more months.

I know not much info is given, but I explained it as best I could. It's basically just a kinda faint thud. It will only make the nosie like 2-3 times, then no noises until I stop and take off again. I do get a faint whine in the rear end when cruising at higher rpm's in first gear. But other than the thud/click there's no other sounds.

Does anyone know what this sound indicates? It's hard to pinpoint it as this car is very loud and the exhaust dumps at the axle. It's just somewhere between the tranny and axle.

[SSedan64]

What Trans is in the Car??
Check your rear Trans mount & U-joints 1st.
Look for scrape marks on DS tunnel.
Bad mount>> Torque may be allowing the rear of Trans to rise causing the U-Joint, DS/Driveshaft to contact the bottom of floorpan/DS tunnel.

[valtiel43]

Originally Posted by SSedan64

What Trans is in the Car??
Check your rear Trans mount & U-joints 1st.
Look for scrape marks on DS tunnel.
Bad mount>> Torque may be allowing the rear of Trans to rise causing the U-Joint, DS/Driveshaft to contact the bottom of floorpan/DS tunnel.

It's a 350 turbo.
That could be what's happening, as it does sound a little like something knocking. I'll check it out.
If that is the problem do you have any advice on fixing it?

[68NovaSS]

If a broken rear mount is the problem, replace it. While you're at it, check the drivers side motor mount, there's a possibility it separated first, allowing the motor to torque up, causing the rear to break. Easy to check, in gear, throttle up holding the brake while someone watches the mount...from the side.