atari_st

I have an 86’ 928S Auto with 115K. When stopped and in gear (drive or reverse) I have a whine or high pitch roar coming from the transmission area. As soon as I start moving (even an inch) or place the car in neutral, the sound stops. Any ideas? This sound is in addition to bearing noise I am currently getting from either the torque tube or the bearings on the flex plate shaft/bell housing area. I have plans to drop the rear end next weekend to replace the bearings on each side of the bell housing as well as test the torque tube while the transmission is out of the car. I do not believe the whine/high pitch roar I hear has anything to do with the bearing noise in the torque tube or bearings on the flex plate shaft since I only hear it with the car at a full stop. My thought is that since the torque tube and flex plate are turning even when the car is at a full stop I would hear the sound while moving unless pressure is being applied at full stop then once the brake is released and the car starts moving the pressure is reduced. Again, the noise only appears when the car is at a full stop in gear. My thoughts are: (1) Bad torque converter…but the car shifts fine with no other signs of failing (2) Worn bushings on the main pump that the torque converter attaches to inside the transmission case (3) one of the bearings I plan to replace (4) Bad transmission mount…which can cause tension in the transmission suspension or insulation problems. (5) issue inside the transmission…… I want to try to figure out what it may be since I am going to have it out next weekend. Any pointers would be great.

Garth S

Just a bump to keep your good question in view, as I do not know the answer; however, before taking anything apart, I'd put the car in the air, engine running in drive with the parking brake on - and stethoscope every millimeter from the flywheel to differential - trying to pick out things like the pump, convertor bearings, ...

aguk928

Could be the primary pump on the auto box.

Big Dave

Just remember that the torque tube is going transfer sound from one end of the car to the other. After I had my new tranny installed, part of the torque converter wasn't tightened down. The resulting sound was difficult to pin down to the front or rear of the car....it sounded the same at both ends.

Steve Cattaneo

The noise you hear in drive or reverse at a stop, is a turbine noise. The torque converter is bad. If you remove the transmission, replace the flex plate flange and torque tube bearings.

atari_st

Well......Replaced the two bearings on the bell housing.....noise is GONE!! I am not sure if this was the issue that was causing the noise at the rear of the car…but…when we put the transmission back in, we had to pull it back off for a few seconds to remove the screw in the torque shaft at the transmission to get it to slide back on the torque shaft correctly. Once we got it back on, the clamp would not line back up with the torque shaft in order to put the screw back in the clamp. The torque shaft had shifted back farther from the front of the engine to the Trans.....I guess when we pull the transmission back towards the rear of the car....it took the torque shaft with it.......which obviously means the shaft was not tight enough at the engine.....therefore when in gear and not moving, the shaft may have been shifting in the torque tube applying pressure at the transmission. We lined the shaft at the transmission…..put in the screw….then moved to the front of the car and repeated. It is amazing how quite the car is now.

SteveG

Atari: I am not familiar with ATs, so I may be off base here but the movement of the shaft you describe while installing trans prompts me to bring up the dreaded flex plate issue. There are multiple threads here on checking that periodicly on ATs to avoid thrust bearing destruction/problems.