Signs of bad torque tube bearings?
09-02-2017, 11:25 AM
#16
Drifting
This is what mine sound like before I repaired. Sounded like loose heat shields or exhaust rattling.
I have uploaded videos on how to remove and install the TT if you choose to try this yourself.
09-02-2017, 11:29 AM
#17
Drifting
I read Dwayne's write up on TT overhaul in which he discusses migrating bearings. I recall he measured the distance to his forward bearing and it wasn't in the proper location. I don't recall what reference he was referring to, but when I did my flex plate release and crank end-play measurements (dial gauge, not digital calipers) I measured the distance to my forward bearing and it was where it is supposed to be (11 inches and change). When I helped a fellow owner do the same release and end-play check on his new-to-him 928 I was curious to see where his forward bearing was sitting....it was at exactly the same ~ 11.xx inches. Based on what Dwayne described and two data points I've measured, I would measure the distance to the front bearing and see what you get. Of course it's just the forward bearing, but it is an easy WYAIT thing.
Last edited by Captain_Slow; 09-02-2017 at 02:58 PM.
09-02-2017, 11:42 AM
#18
Rennlist Member
+If it is the torque tube bearings, then Constantine's rebuilt torque tube with Super Bearings is the way to go if you want a "no worry" solution. Another good step is to use one of his or one of Greg's new drive shafts while you're at it.
09-02-2017, 05:27 PM
#20
Rennlist Member
Constantine:
http://www.blackseard.com/site/
As of last year he was still providing assembly and was very responsive to all questions. Greg Brown has a souped up 25mm driveshaft. Greg shipped to Constantine and the whole package came to the shop ready to drop into the driveline.
http://www.blackseard.com/site/
As of last year he was still providing assembly and was very responsive to all questions. Greg Brown has a souped up 25mm driveshaft. Greg shipped to Constantine and the whole package came to the shop ready to drop into the driveline.
09-02-2017, 08:11 PM
#21
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09-02-2017, 08:35 PM
#22
Rennlist Member
Dave, I wrote then deleted a more complete description on purpose. After we finished that job I came across Dean's solo TT replacement video. It makes it look pretty drop-in easy. That's the impression I hope the OP has. Not the one where I have a deep scar and last year's dirt in my eye. Learned a lot, helped a little.
09-10-2017, 03:22 PM
#23
Rennlist Member
Thread Starter
Crawled under the car today with a rubber hammer. Nothing seems to be loose. I removed the bell housing. With the engine running and that cover off the rattling is pretty pronounced. Guess I will be doing the bearings...ugh
12-01-2017, 01:40 PM
#25
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I'm looking forward to TT bearings as a winter PM project. Mine isn't particularly noisy (yet) but based on time/miles we are getting up to the bottom of the range where it becomes a more likely failure.
Oh Boy!
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The easiest diagnostic tool for this is a stethoscope. In all cars auto or manual, the driveshaft in the tube spins at engine speed. With the car safely lifted so you can get underneath without getting burned by warm exhaust plumbing, and with said exhaust plumbing safely vented, run the engine at idle. The front of the torque tube is connected to the rear of the bellhousing, where you can poke your mechanic's stethoscope probe to listen for bearing noises. Similarly, the rear end of the tube has an access through the heat shielding just forward of the TC cover at the front of the automatic transmission. On manual cars it's a little easier to get to the back end of the tube, no torque converter. Listen for a rumbling noise that changes amplitude with RPM much more than it changes frequency/pitch. Automatic cars have a pair of bearings in the front of the torque converter housing that carry a short shaft and drive flange for the converter. Listen for these bearings at the torque converter housing. The bearings and ***** inside are smaller, so the noise they make will be higher-pitched than the torque tube bearings at the same engine speed. There's no justification for taking everything apart and not changing both the torque tube and torque converter housing bearings at the same time.
Related:
Manual transmission cars add throwout and pilot bearing noises to the mix. The clutch throwout bearing makes a rumble similar to a torque tube bearing, one that changes depending on pedal depressed. The pilot bearing in the rear of the crankshaft is silent until the clutch is released, with noise often lost in sounds from the clutch especially in dual-disk setups.
Some automatic transmission cars have a riveted drive plate for the torque converter that rattles when the rivets grow the holes they fit in. There's a TSB someplace about this, with the solution a set of hardened bolts after the rivets are removed. The drive flange will be out in your hands when you are changing the torque converter housing bearings, so it's the most opportune time to address this issue. The symptom is a rattling noise at the torque converter housing with the engine idling.
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I will advise against casually listening to automatic transmission noises as you are under the car with the engine running, and for sure not with the transmission engaged in any gear. The stethoscope reveals what's either a symphony of sweet mechanical noises, or a horrible mix of sounds akin to silverware in the blender. Same actual sounds, different subjective interpretation.
Oh Boy!
----
The easiest diagnostic tool for this is a stethoscope. In all cars auto or manual, the driveshaft in the tube spins at engine speed. With the car safely lifted so you can get underneath without getting burned by warm exhaust plumbing, and with said exhaust plumbing safely vented, run the engine at idle. The front of the torque tube is connected to the rear of the bellhousing, where you can poke your mechanic's stethoscope probe to listen for bearing noises. Similarly, the rear end of the tube has an access through the heat shielding just forward of the TC cover at the front of the automatic transmission. On manual cars it's a little easier to get to the back end of the tube, no torque converter. Listen for a rumbling noise that changes amplitude with RPM much more than it changes frequency/pitch. Automatic cars have a pair of bearings in the front of the torque converter housing that carry a short shaft and drive flange for the converter. Listen for these bearings at the torque converter housing. The bearings and ***** inside are smaller, so the noise they make will be higher-pitched than the torque tube bearings at the same engine speed. There's no justification for taking everything apart and not changing both the torque tube and torque converter housing bearings at the same time.
Related:
Manual transmission cars add throwout and pilot bearing noises to the mix. The clutch throwout bearing makes a rumble similar to a torque tube bearing, one that changes depending on pedal depressed. The pilot bearing in the rear of the crankshaft is silent until the clutch is released, with noise often lost in sounds from the clutch especially in dual-disk setups.
Some automatic transmission cars have a riveted drive plate for the torque converter that rattles when the rivets grow the holes they fit in. There's a TSB someplace about this, with the solution a set of hardened bolts after the rivets are removed. The drive flange will be out in your hands when you are changing the torque converter housing bearings, so it's the most opportune time to address this issue. The symptom is a rattling noise at the torque converter housing with the engine idling.
----
I will advise against casually listening to automatic transmission noises as you are under the car with the engine running, and for sure not with the transmission engaged in any gear. The stethoscope reveals what's either a symphony of sweet mechanical noises, or a horrible mix of sounds akin to silverware in the blender. Same actual sounds, different subjective interpretation.
