Greetings all:

I have a 1984 pontiac trans am with overdrive. My problem is that I put my car into reverse with the parking lot asphalt wet with rain so I thought I would spin tires a little bit (I don't do it that often.) Anyway everything was going good, but then when I came to a stop and started turning to the left and creeping forward to a speedbump, I heard a loud grinding gear noise coming from the center of the car, I am guessing its transmission location. (I know nothing about the mechanics of cars) So I stopped shut off the engine and looked under the hood. Nothing spurting out anywhere or anything like that. I fired up again and started creeping forward again, same loud grinding noise came back. Stopped when I hit the brakes. Finally getting on the road the grinding noise sped up but lower in volume. It finally went away at 30 mph. When it hit 35, it came back and got louder and faster. I have no idea why I thought this but I thought maybe if I went faster then maybe it would finally go away. I sped up to 45 got faster and I think louder. I got it down to 30 put on the emergency lights and came home. I parked it, checked the trans fluid. It showed full and a beautiful red color on the dipstick. So I fired her up and put it into reverse. To my surprise, it made a grinding noise going reverse but not as loud as going in Overdrive. I have no idea what's going on or what to do. Can anyone please help me with this? I hope to *** that I do not have to get the trans rebuilt or get a new one. Btw, my engine is a 305 V8 I have no idea what transmission type or even are in 2006 6 years ago. I had the trans rebuilt then. I want this thing fully operational aknow how to identify it. I got this car 5 well now since we nd I hope I never have to have any other work done to the transmission.

Thanks to all who reply and all feedback is most welcome.
Jeff

 

Check your flywheel bolts, I had that problem. I've also seen where the starter gear doesn't retract all the way and the flywheel just hits it enough to make a terrible noise. Does it make the noise whenever the engine is running or just when moving?

 

Later today with a neighbor that it makes a slight grinding noise when idling in park. I shifted to OD and moved a bit and we heard it grind, then he had me back up. My mother was beside the car and she said she saw the rear wheel act like a stop sign. In other words it didn't spin like a circle it acted like a stop signs shape with angles. Also it jumped quite a bit when going reverse. Neighbor looked under the car and said the universal joint to the rear was shot. Have no idea what that is or what it does. He said he has to take off the driveshalft and redo the universal joints. Something about pressing them together and then putting them back on and it should work fine. I dunno about all this stuff but I was told NOT to drive the car at all. I was lucky he said that if I drove any further the driveshaft could have actually fallen off. Is that true?

 

for sure, the universal joint holds the driveshaft to the back of the transmission (output shaft) and hooks to the pinion gear the same way on your rearend to connect the 2 together. Universal joints have many many needle bearings that go bad sooner or later (usually later). I beleive our cars have sealed u-joints which is a + for most us that don't feel like lifting the car to just greese the zerk fittings. If they are shot they will need replaced though not repacked and put back together.

not sure what particularly was wrong with yours, they can be ruined and mangled in many ways so to say.

 

Look at your tranny mount. Most likely cause of your problem is a broken mount that allowed the tailshaft to shift to one side bringing the driveshaft out of alignment with the rear end/tranny. This could have then damaged your u-joints. Probably popped the tranny tailshaft loose when you spanked your tires.

Doesn't explain the grinding noise in park though...??

Get under the car check the mount, you may see that the tailshaft is canted to one side (not centered on the mount). If it looks good, place a jack under the tranny pan with a block of wood between the pan and the jack head. Slowly lift the trans up slightly while watching the rubber mount between the cross member and the tailshaft. If it's bad you'll see it separate.