AO

I'd take a peak at the clutch (easier than the TT). There are a number of bolts that hold the presure plate to the flywheel. If one backed off, it could lead to an out of balance situation.

justin

What is the easiest way to do that?

AO

You may have to drop the catalytic coverter. Then it's just 6 bolts + 2 more for the slave cylinder. Biggest part is dropping the exhaust. If you do drop the cats, when you're done, don't put in the rearward 2 bolts on the cover so you can take it off again in the future without having to drop the cats.

ErnestSw

Justin,
You can count on the help of the DFW gang for diagnosis and help with repair. We'll even give you the "member discount" (10% added to the bill).

AO

Justin-
Run, don't walk!

Seriously, though, talk about a support net.

justin

Ernie, I think Im going to need it on this one, Andrew thanks for the help, keep it coming guys.
-Jus

Jim bailey - 928 International

What you describe is probably a clutch issue which has now caused the forward most bearing carrier in the central tube to migrate all the way back to the center of the tube. The initial problem could have been the pilot bearing was worn so it no longer centers correctly and the clutch pack when you depress the pedal and release it no longer hits in the same spot it might or might not be centered. The subsequent imbalance when it is off center could then make the forward bearing move this lack of support then puts more strain on the pilot bearing and guide tube. When you push the clutch down and release it the clutch pack is hitting the flywheel randomly sometimes more centered sometimes not. This condition can easily become MUCH WORSE and some have broken the short clutch shafts this way.

justin

Thanks Jim, whats the fix?

Jim M.

Justin,

Here is a test to determine if it's the torque tube, and isolate it from the engine. 1. Car in neutral rev to 3500-4500, vibs very noticeable (sunroof shakes). 2. Car in gear, rev to 3500-4500, vibe present at 3k. 3. Drive car, bring speed up so you’re turning 4k rpm in 4th gear, shift into 5th and maintain speed, depress clutch pedal and let revs fall to idle. Keeping clutch depressed, slide gearshift into 4th. If you notice the vibration spooling up you have torque tube bearing issues. On spool-up the vibes should be softer then under power.
1. Bring car to speed in 4th gear where vibes are worst. 2. Change to 5th gear and keep speed steady. 3. With car still in 5th and at speed, depress clutch and let engine speed fall to idle. 4. With car at idle, clutch depressed and still rolling along slide shift lever into 4th very slowly. Be sure to observe for vibrations returning. This test isolates (for the most part) the TT from the engine. When doing the 5th to 4th test, be careful to note the vibration return behavior. If the vibe appears to spool up when engaging into 4th, it’s most likely the TT. The TT spins almost all the time regardless of clutch position due to inertia and parasitic coupling. I also agree with Jim Bailey's analysis.

The DFW group is ready to help whenever you say, just pick a date.

Jim Mayzurk
93 GTS 5-spd

justin

Ok Jim, thanks, I just got off the phone with Jim Bailey, he wants me to pull the lower bell housing and take a look at the clutch, then loosin the coupler and slide it back, then take a piece of wire and feed it down the tube and check to how far the front bearing is down there. He suspects its moved down the tube, I am probally going to drop the clutch and look at the pilot bearing. Ive never done this before so wish me luck, I am off to get my WSM's.
Thanks guys

ErnestSw

G'luck. The 928 clutch is no big deal.

User 4221

Yep... That described my 1981 TT exactly.

Hey Mayzurk, can I get some royalties on your quote?
At the very least, can I get a ride in your car?

Chuck Schreiber

Justin,

The rattle you describe is what my 79 does in 4th gear exactly at 4K rpm. It buzzes like crazy!!!!
Also, in neutral (standing still) I have a slight "gurgle"? sound coming from somewhere down by the clutch. When I depress the clutch, it goes away.
Jim, does this sound familiar??

Jim M.

Huh? What quote???? You can get a ride in my car anytime. Come to our next gathering or the next tech session. Why didn't you ask on Sunday?

Jim Mayzurk
93 GTS 5-spd

Jim bailey - 928 International

If and when the torque tube bearings begin to fail they can have a hum bearing whine when the clutch is up trans in neutral. Depress the clutch and as the drive shaft slows and stops the whine slows then stops. With it in neutral if you rev the engine (clutch pedal up) the whine changes. Now about the 4,000 rpm 4 th gear rattle. Only in 4 th ? That if it is the case sounds more trans related since the clutch and drive shaft spin at engine speed 4,000 rpm is 4,000 rpm no matter what drive gear so for it to be only in 4th it is probably a bearing issue inside the gear box .