UKKid35

A couple of hours before my engine died I had my friction plate replaced. I'd previously had quotes of $1000 to $1400 for a complete clutch fitted, this was out of my league so I quickly accepted the offer of a new friction plate for $250 plus $100 fitting from a part time independent.

After fitting I was concerned about some clutch pedal vibration but my cam belt failed before I had much time to think about it. Could the vibration be anything other than the pilot bearing?

The pilot shaft came out fine when the friction plate was replaced, how long does it take for the bearing to disintegrate so I'll end up with a grenaded bearing like this?

http://members.rennlist.com/jeifert/DD-CLUTCH-REP.html

UKKid35

Do I get a prize for the least views and replies?

porsche1662

I am listening Mr. Uk. I just don't know anything about that. I am posting this reply to put you back on top of the list so you have a better chance. Hows the weather over there. It is snowing here. Browns are done Cavs doing well for a change and Baseball coming soon. Go Tribe !!

Garth S

To venture into speculation.....
Paul, I' ve only done the twin disc unit; however, assuming the type of vibration you have is a constant thing with clutch released "whilst" driving(if not, pls. specify the nature of vibration), can offer the following:
It is unlikly the pilot bearing failed 'overnight' while changing the clutch disc, although, it's always a good idea to change it when in that far.
The S4 pressure plate is dowel-pin centered, but I'm unsure if the pins are asymetric, alloving only one orientation on the reinstall: if not, the general trick is to mark the pressure plate/flywheel prior to dissasembly so as to insure vibration free reassembly.
The other point is that the clutch release arm was removed by popping it off the upper ball stud pivot point: The nylon bushing in the release arm socket is a known wear item, and may have crumbled to bits during the process - this can lead to a pedal vibration, and is perhaps the most likely issue.
regards

porsche1662

UKKid35

Thanks Guys.

Garth you are right I wasn't very clear about when the vibration occurs: slight but quite noticeable before the pedal is depressed, and very pronounced when the pedal is depressed until released. I would say it was uneven vibration rather than rhythmic, I can't remember whether it happened more when changing gear than when stationary and in neutral - and I won't be able to check for some weeks.

I did ask about replacing the nylon bushing, I was assured that mine was ok (might not be though!) this should be much easier for me to check now half the engine is out.

Garth S

Paul,
How did the clutch perform prior to replacement of the disc? One assumes the pressure plate 'fingers', release bearing, etc. were examined by the mechanic, as was the nylon cup??
Anyway, a vibration occuring when the clutch is engaged that becomes worse when disengaged(depressed) has most, but not all, of the signs of a failing release bearing; however, if it worked well before....
One of the simplest things to check after you wrestle your current monster rebuild to the ground is the presence/absence of lube on the guide tube:It's contact w. the release bearing may be an issue. Somewhere in the Tech. links ('Keepers' by G Nichols, I think), there was a good descriptive of lubing the splines/tube/etc with the clutch installed - an easy to do, 'can only help' type of job that only requires dropping the lower cover.
As you can guess, this is a guess!

UKKid35

Thanks again Garth, I've checked the nylon bushing in the release arm socket, just by touch to see if it has obviously disintegrated, and it hasn't - no significant play. So I guess the clutch will be coming out once the engine's running - not before as I'm going to need it as a flywheel lock again.

UKKid35

There is no pedal vibration anymore. In my 200 yard test drive yesterday the clutch was perfect. The only weird thing that happened when I removed the clutch slave cylinder 3 months ago was that there was a loose nyloc nut floating around behind the rubber boot, how it got there I have no idea. I don't think I'm going to have to pull the clutch out after all - yippee!

Jim_H

Good Karma!

How is everything going?

Jim bailey - 928 International

The nut may have been used to "fix" a stripped bolt hole for the guide tube (sleeve) which locates (centers) the release bearing . If that were loose the release bearing can float around a bit on the spring fingers .

UKKid35

Thanks Jim, you may be right as unfortunately I spoke too soon. It seems a 200 yard drive in first isn't quite enough to test a clutch properly - Doh!

I took the car out for an hour last night and the clutch problem has returned, I guess I'm going to have to replace the bearings - more business coming your way Jim!

UKKid35

The cause of my clutch pedal vibration: The Guide Tube Bolts were missing! There was no sign of them loose in the bell housing so I have to assume that they were lost when the friction plate was replaced, as the vibration started immediately after. In effect Jim was right - as usual.

With Jon928se's help (read - garage, tools, ingenuity) we replaced the Release Bearing, Guide Tube and Pilot Bearing. Both bearings were on the point of failing. Thanks to 928 Int for supplying a good used release bearing at a price I could afford.

The old Pilot Bearing had not yet grenaded, but it was very sticky, with the new bearing gear changes are now twice as fast, and the dodgy synchro I have on 3rd is much less prominent.

I do have some hairline cracks on the flywheel surface and I will post pics shortly, I'd been interested in your thoughts.