Jim bailey - 928 International

Loaded , basically figure $495 for a rebuilt tube plus 150 for broken shaft plus labor of about 12 hours at your favorite dealer... except he will want to use a new tube at about $1,800... so you can see why Bill Ball is so highly thought of by so many people !

Bill Ball

Had park actually not been working that would have been the right vote.

Nicole

Whoa! This is prety scary! And quite a job to fix, as I understand. If you've got to remove the transmission, there ight be some WYAITs to consider doing...

Bill Ball

We are going to try a different way of replacing the TT.

Hey, it's a TT party!!!!

Jim bailey - 928 International

Long distance automotive diagnosis is always interesting especially with bad information or incomplete information. Reminds me of the time I saw some guys from a body shop pushing a car by hand and trying to bump start it ...so I helps them do two or three more attempts we stopped to catch our breath and the next thing I hear is the engine cranking over on the starter motor just as fast an nice as could be. I asked Edwardo the manager who was behind the wheel why they were pushing it and he said because it would not start on the starter motor.....

Mark Anderson

I had similar issue when I broke the torque tube on my race car. There was enough friction on the broken shaft pieces that on the hoist the wheels spun just fine but under load they would not.

borland

What's the history of the converter bearings? Those probably should be replaced based on milage alone.

There's a TSB covering the broken shaft. Running on 4 cylinder mode is what causes this delayed shaft failure. It's also a risk with using a rebuilt TT. The PO just drove it too far before getting the problem fixed.

Jim bailey - 928 International

Bill one short cut literally is a cut....the small lower cross brace of the upper bell housing ! But I know you have been contemplating dropping the bellhousing after the experience slipping out the flex plate .

Bill Ball

Yes, that "shortcut" would allow you to leave the bellhousing inplace. I figured out how to get the bellhousing out easily. What hangs some people up is the bracket for the bowden cable. You do NOT need to remove that inaccessible bugger. You just release the bowden cable from the throttle quadrant. Unbolt the bellhousing and it will fall out. Loosen the tranny mounts, swing the front of the TT down far enough and everything comes out.

borland - I think the TT by itself can be a quick job the way I want to do it. If Matt wants to do the TC bearings on a 75K mile car, I'm probably not going to be too thrilled about doing that. I know some of you guys think dropping the entire rear is a piece of cake. Not me. We're working on jackstands and do not have any equipment to raise and lower the rear suspension and tranny. We can debate that some more. Maybe I can be persuaded to try it.

BC

I always think dropping the suspension on these cars is easy - but then when I go and do it again I do remember all the little things that need to be done.

Bill - Can you not unhook or somehow disconnect the entire front of the TT from the Bell housing (I remember - inside bolts) and then as you say drop down the TT front to get to t he reat TT bolts? After that the TC bearings should be right in your face (on a lift)

Tony

Great picture!!

Does the end of that TT taper down or is it a constant diameter?
either way, IMHO, i think the cause is corrosion...you can see its apears internal on the "shreaded" end

Your in good hands with Bill up there.

Bill Ball

Tony:

It's the infamous neckdown stress point of the 86+ shaft. As Jim reminded me last week, the early thinner shafts don't have this weak point. Are we living on borrowed time??

Bill Ball

Brendan:

I thought the TC had to be removed and that can't be done with the tranny in situ, but that is something I was going to examine while we are in there. Isn't there a rear and front bearing? We could do the front if it is right there in our face.

I do plan to unbolt the bellhousing and the front of the TT and swing the TT down, after removing the exhaust and shielding. I expect the rear TT bolts to be accessible and the TT to come out.

Jerome Craig

Bill,

You're a good man! I've seen how willing you are to help others, and you've sent me some good advice. We appreciate you!!!!!

Jerome

Tails

Interesting fault finding and long distance diagnosis, plus very interesting photographs of the failure.

As my car is not fitted with 'cats' nor heat sensors on the left and righ exhaust manifolds or ignition cut out circuits it should not be subject to the uneven torque loading that can occasion with 'cat' cars.

It would be interesting to get a metalurgical diagnosis as to the cause of the failure, so as to determine whether it was 'uneven torque' related high stress due to continuous running with one bank of cylinders cutting in and out at what appears to be the junction of the tapered section of the drive shaft at its junction with the spline or some latent defect within the material of the drive shaft or a stress riser due to the machining in the area of the fracture or whatever.

If this metalurgical diagnosis can be done it may give us some indication of what to look for when we, with car with automatic boxes, when we check the forward flexplate migration and loading up of the thrust bearing in the engine at each oil change.

Bob, I look forward to reading about the short cut method of the removal of the TT and drive shaft.

In closing I don't like saying that its good to see you located the reason for Matt's car's failure, however, it is always a relief to know what the problem is as now you can plan exactly what needs to be done.

Hope all goes well with the TT party Bob and Matt.

Tails 1990 928 S4 Auto