87 944 t - was driving on flat road, not racing. had just changed into 2nd gear, when a very loud bang ended the drive to the rear wheels. engine continued to run. i pulled over and found that clutch peddle could be moved in and out, gears could be engaged and clutch let out fully without the car stalling or moving ie. rear wheels would not turn by engine whether clutch was in or out. no noise occurs when these procedures are done. car was towed home. i put the car on axle stands with the rear wheels off the ground. rear wheels turn when turned by hand with car in gear. if i block one rear wheel the other turns and visa versa.
question - what are the possible causes, and how do i test to eliminate the possibile choices of problem - advice please
regards rockiel

 

Torque tube

 

Thanks Andrew
i'm reasonable handy, how long and how much - or best left to a professional

 

Look in the trans inspection window (black trapaziodal rubber plug covers it) while engine running and in 1st gear <be careful doing this from the rear of the car, front wheels chocked in case something "catches">

If the torque tube is spinning, it's a ring and pinion failure (because your diff works). If not, it is clutch disc completely letting go at the center hub (more likely) or a snapped torque tube (less likely).

I'm interested to find out so please post back.

 

Good recomendation to check if the driveshaft (inside the torque tube) is spinning when the engine is on. Putting the car on jack stands then removing the access cover for the driveshaft/transaxle coupling and looking in with a flashlight should tell you.

In gear, if it spins, something in the transmission let go.

If it's not spinning, something in the clutch/driveshaft has broken.

Good luck.

 

could also be the coupler to the trans/tt.

 

sounds more like an axle came undone/bolts fell out.

Mark

 

yup, same thing happened to mine couple of weeks ago, a loud bang, and rear wheels won't turn

I might have gotten lucky, because it was only the coupler

the part is like $350-390 @ the dealer, and you need to lower/take off the transmission to change it; my brother and my friend changed mine on a lift, and it took them about 5 hrs total

 

I doubt it's a broken torque tube, especially on an N/A. Only car I've seen break it's torque tube was MPD47's, and he's pushing 'just a bit' more power than an N/A.

As soon as I heard the description I was thinking it was the ring & pinion gear, especially with the loud bang. I'm skeptical that the clutch letting go would be very loud. The trans. coupler would probably be pretty loud as well though.

Just be careful running the engine while it's on jack stands....

 

+1

 

I dont think it's a bolt(s).

 

He said it's an 87 944 t... I would think the t means turbo. That same trapezoidal shaped window is where the transmission coupler lives. Try this, with the car in gear, engine shut off, reach in the trapezoid hole and grab the coupler and try to rotate it by hand. With the car in gear, you shouldn't be able to rotate it much. If you can then it is probably a clutch problem. Then put it in nuetral and try to rotate it again. It should spin and one of the rear wheels should turn (right side I think) also, assuming it doesn't have limited slip in which case both rear wheels should turn. If there is no wheel rotation then I'd have to say pinion gear has lost teeth.

 

Was thinking axles, until he said the wheels turn when one is rotated.
I have to put myself in the Ring and Pinion camp.

 

Quess I should have read the entire paragraph, not just the first sentance or two

 

Clutch is most likely since ring and pinion will not allow the rear wheel to spin freely for a while before it gets stuck due to broken gear tooth in many cases.