ok heres the deal my rear end gave out on me a few months ago so i swapped it with a 95 z28 rear. the other day as i was driving slow i heard a knocking noise and it seems to do it more often when i have my foot off the pedal, when steering left and right (slow) the noise is more noticeable, seems to do it when the car is coasting. i don't think its my U joints because there is no vibration. im going to change the gear oil tomorrow with Lucas oil. and make sure everything is tight.

any other suggestions? im all ears

Put your car on stands and inspect it before you start changing parts. You may have some mounts or bushings that have "gone south." Check engine mounts, trans mount, torque arm mount and lower control arm and panhard rod bushings. While you are under the car, inspect your steering for play as well.

The same thing happend to my car. It was the torque arm that was loose.

ok i made sure everything was tight changed the gear oil but i still hear knocking coming from the rear. i am convinced to think that my rear is going out. so does anyone know of a place where i can have this problem fixed? i did a search around my area but no luck. thanks.

ps i was thinking of upgrading my gears what are some decent gears to get? btw the rear is from a 95 z28 auto.

I don't have a fourth gen rear but On my car I was hearing a popping/knocking noise coming from the rear and I was sure it was the differential. It ended up being the trans mount...again!

Might be good idea to raise the back wheels off the ground and use a stethoscope to locate exactly where the noise is coming from. One of the shops I had working on my car in Hawaii misdiagnosed a noisy problem, replaced the rear end and later discovered the grinding sounds were coming from the transmission.

that also makes sense but like i said the noise is more noticeable when im driving slow and at the same time steering left and right. if it was the tranny mount shouldn't the noise be more consistent? but either way ill check the tranny mount anyway. thanks

Sounds like they didn't put the limited slip additive in or use Red Line Non Slip. On the autox cars, rears w/o the additive would make a "popping" noise when turning at low speeds.

i don't think you need an additive when your using Lucas oil 80/90 limited slip

Yes you still need the additive if you are running an Auburn. Most gear oil doesn't have the additive (modifier) because of the cost. Some have a "cheap" version that burns off.

You get it fixed yet?

yeah i installed a different rear end from a 91 iroc with posi. feels and sound allot different, but no i didn't add any additive. being thats its Lucas oil, but i have to many people telling me to add an additive, and some say that it doesn't need it because of the oil I'm using but ill try adding some type of additive.