So, I'm in the middle of a TT rebuild job, and I've just released the short shaft guide and pushed it back into the clutch housing, and the rear shaft coupler is loose and slide back into the TT.

I've been reading up on the replacement instructions in the WSM 30-06 volume 2 (with the updates for the Single Disc Clutch). I can't seem to find a photo documented write up on the single disc clutch and I'm being overly cautious as usual.

I've manufactured the 2mm sheet metal 90 degree angle shims that are supposed to slip into the notches of the pressure plate. But the shims appear to be just a little to thick (the clearance is definitely less than 2mm). See first photo.

So, next question. In photo two, where the screwdriver is pointing , are these the mounting bolts that I'm supposed to release by 1 1/2 turns to cause the pressure plate to grasp these shims? Loosening them doesn't seem to be doing that.

In Photo 3, are these the positioning pins that need to be driven towards the flywheel? In photos 2 and 3 see another pin that is sticking out through the flex plate near the release lever... Perhaps those are the pins I should be driving in?

The last photo simply shows the existing gap for the shim.

Super frustrated here with what I thought was going to be a simple job. It's really too bad that the top two TT bolts weren't bolted in from the outside instead of from the inside of the bell housing... Grrr.

 

The clearance will be zero when the clutch slave and lower bellhousing are off, and the diaphragm spring in the pressure plate is squeezing the friction disc with full force.

Photo #2- yes, those are the (9) mounting bolts. Not sure how loosening the mounting bolts would cause the diaphragm spring to release. If you had the pressure plate out on the bench, there would certainly be no gap to insert shims.

You have to dis-engage the clutch to get the shims in. In-car, the only way to do that is to lever the release arm towards the rear of the car, which counteracts the diaphragm and opens up the gap in the PP for the shims. I have never tried it, but alternatively you might be able to rotate the engine so the spot for the shim is at 6 o'clock, and then use a C-clamp to squeeze the PP and insert a shim. Then rotate 120o clockwise and repeat x2. Be aware that the PP is VERY heavily sprung, I had to use a cheater bar to turn the screw on the C-clamp to open up a gap for the shims.

Here's how an S4/GT/GTS clutch is shimmed on the bench:




The shims go in during removal, are transferred over to the new PP on the bench, the clutch pack is re-installed, and then the shims are removed in-car by levering the release arm rearward.






Photo 3- those are the rivets that hold the timing ring onto the pressure plate. Don't hammer on them. In my 90GT there were no locating pins driven thru the PP into the flywheel, I'd expect there would also be none on a '91 GT.


Pics of the release bearing R&R are here:

https://rennlist.com/forums/928-foru...g-problem.html

 

First, I suggest that you search and find Rob Edwards recent write-up on clutch R&R.

That said:

1 - You might have to pull the release bearing back in order to get the shims in place. You can use a come-along from the rear cross member to the throw out release arm to do this. You could just pry the pressure plate back, but that seems a little inelegant...

2 - These are the pressure plate retaining bolts indicated in picture two.

3 – No, that is not one of the little pins in picture three, it is a rivet that holds the ring gear to the pressure plate housing. The pins do not have heads and are inset into their respective holes. You might find them more easily if you look at the engine side of the flywheel. Note that one is a different diameter for re installation.

4 – Do not forget to release the throw out arm from the top pivot before you start to remove the pressure plate-to-flywheel bolts.

Removal and installation are not really hard tasks, but the combination of clutch, pressure plate, throw out bearing, release arm, and short shaft are an awkward package.

HTH

Bob

 

I have a writeup from a rennlister that was very helpful when I did my clutch. If you want, send me your email address and I can send it to you.
Bilal

 

Rob - Thank you. This is helpful information. I'm not planning to rebuild the clutch at this point, I'm simply planning to drop it, rebuild the TT, then re-install it.

I am assuming that getting the shims in is required before removal of the clutch assembly, even if I'm not planning on replacing the pressure plate.

I really appreciate the comment about your '9 GT not having pins. That answers a mystery that I was really struggling with.

Bob - Thanks for the reminder on #4 above. Seems like the release arm is going to be first useful, then in the way during this process. I'll be sure to get it off the ball joint at the top before trying to drop the clutch out.

I still wish the Germans had set up the TT bolts to anchor into the bellhousing instead of the TT... Would have made this job a lot simpler! I'm sure that it has to do with materials, but what a pain...

Sending PM to Bilal (thanks for the offer to help!).

I'll update the thread with anything I learn tonight. Thanks guys!

 

You know you can remove those four front TT bolts without dropping the clutch right?

Dan
'91 928GT S/C 475hp/460lb.ft

 

Dan,

I'd love to know how to do that. Can you also torque them back to spec without dropping the clutch?

 

As as been written, the shims can be inserted once the pressure on the disc has been released. I (carefully) use a pry bar between the release arm and the center of the PP.

Pop the release arm ball cup off the ball after you have removed the bolts that secure the clutch assembly to the flywheel - and only do that when you are ready to catch the assembly with something other than your head. If you do it in reverse it is easy to get the assembly 'cocked' in the bell housing as you rotate it to get the bolts out so that it is a total b1tch to get out.

This is how I drop a clutch: turn-out starter bolts almost all the way until the starter can be pushed forward. Unbolt the guide tube. Break loose each PP bolt and, as you turn the assembly, lever the arm back to insert the shims. As you rotate and break loose the PP bolts, as the pinch bolts on the intermediate shaft clamp rotate to the right orientation, remove them.

Once the shims are in and the clamp is pushed back, turn out each PP bolt. When the last bolt is out, pry back the release arm to separate the assembly from the flywheel, then get ready to catch the assembly and wack the bottom of the release arm to pop it off the ball. 90% of the time the assembly will fall straight out of the bell housing into your waiting hands.

 

You need something like my favrite tool to get the two top bolts out easily, but note what Dan just said. Once you break it free, this tool spins the bolt out in 15 seconds.




You can torque them, but it requires a 5 degree ratchet. The torque is not a critical one, like a head gasket, so I use wahtever wrench setup to get them to he 31 ft lbs or close enough. I can get it that tight with this twist ratchet.

 

I am going to see if I can do it without dropping the clutch. My evening fell apart tonight. Looks like it's become a Saturday afternoon project.

I definitely like the idea of leaving the clutch in place!

 

I was able to do it without the twist ratchet, but it did take a while, about 10 minutes or so for each top bolt since they went one click at a time. The key is the proper length extension(s). The ratchet that Bill linked makes it much easier.

Dan
'91 928GT S/C 475hp/460lb.ft

 

I'll echo what Dan said. I did mine without dropping the clutch. It was really tough to get the gear wrench in there and to get a click out of it, but I did manage. Going back in will be interesting as there is almost no room to get our fingers on the head of the bolt to get it started.

 

into your waiting hands - NO you mean onto your forehead

 

Only the first time.

 

Big thanks to everyone for the ideas.

And huge thanks to NC928S4 (Larry) for coming by today and helping out.

We abandoned the clutch drop approach and attacked with the Stanley Rotator Ratchet and GearWrench Roto-Rachet.

Success!!!

The 5-speed definitely has an advantage here, but those bolts still took us awhile. One had to be backed-out a click or two at a time.