Multiple Clutch Issues

[Stingr69]

I have taken my clutch apart and found some issues. The first thing that I found is known by many people but it deserves a reminder. Do not use a pilot bushing that contains any steel in the alloy. You can identify the wrong material because it will react with a magnet. Back in the day we could easily find the proper bronze pilot bushings (not attracted to a magnet) but it seems it has become incresingly difficult to find the bushings made from the proper material. The common bushings sold today have some iron content in them and do not work as well as the original material. They have a tendancy to gall the transmission input shaft tip and they can make a squeeling noise when the clutch pedal is depressed simmilar to a bad throwout bearing or other transmission problem. I found out the hard way. I have a proper bronze pilot bushing on order from 5speeds dot com.

The next issue I found was that the clutch pressure plate was not clamping down on the disk evenly. If you look at the picture below you will see there has been no significant wear from about 3:00 to 6:00 on the flywheel. From 6:00 and beyond you can see heat checks and small cracks. I suspect the pressure plate was not releasing evenly and the area that is nearly unworn was caused by the pressure plate being out of parralell with the flywheel on release. This setup has not been abused and it was adjusted properly. The flywheel was resurfaced at the time of the new clutch install. It was a Centerforce Dual Friction setup. I am on the fence about just throwing it in the trash rather than just remove the weights and try it again. I just don't need the head aches.

Let me know if you have seen this issue before.

-Mark.

[McKenzieDave]

Yip.  I have seen exactly that issue before.  I blamed it on bellhousing misalignment.  We'll see after the next teardown.

[Stingr69]

Dave,
That is a good thing to check. I have the equipment so why not? The bellhousing is GM so I doubt it would be that far out but just for grins I will verify it. It would have to be pretty far off to cause that much misalignment in the disk. I still want to blame the pressure plate unless I can get evidence otherwise.

Anyone else seen this before?

-Mark.

[68Zproject]

http://www.camaros.org/bellhousings.shtml

[Stingr69]

http://www.camaros.org/bellhousings.shtml

Thats a cool looking tool.

Update - The dial indicator I have is just too big to work for this application. I spent half a day trying to get it to fit but this isn't going to get the job done. It works great for degreeing cams but it just wont fit in this space. I am running a GM 403 bellhousing so that gives me a little bit more confidence. Aftermarket bellhousings are known to be less accurate. If this happens again, we will invest in yet MORE tools and confirm the concentricity.

The flywheel in there was used when I got it but new to me so this strange blued and cracked condition could be from previous abuse. I did have it resurfaced before installing it the first time but this type of previous condition can come back to haunt you even after resurfacing and normal driving. I don't want to stay awake nights worrying about the odd blued and somewhat cracked flywheel with a dubious past so this one is not going back in. 7000 RPM and random junkyard flywheels do not belong on the same car.  I have a new flywheel on the way.

I never really liked the Centerforce DF clutch in there so I don't mind tossing it. I have a new LuK setup on the way.

The crappy ferrous pilot bushing has been popped out with some grease and a stick and the new non-ferrous one is in there now. The tranny is back together and we are just waiting on the rebuilt OEM shifter and clutch parts to show up.

-Mark.

[sixt9x33rs]

I have a NAPA clutch, PP and TOB in my Z and it is junk. I am having that squealing noise too but don't know if it's a TOB or bushing. I bought a LUK today.

[sixt9x33rs]

Stinger,

Can you feel a vibration in the clutch pedal when the galling noise appears?

[Stingr69]

I have a NAPA clutch, PP and TOB in my Z and it is junk. I am having that squealing noise too but don't know if it's a TOB or bushing. I bought a LUK today.

Put a magnet on the pilot bushing. If it is magnetic you want to get rid of it and locate the right non-magnetic bushing. 5speeds.com has them as well as some other sources. If you can't find that then you might consider the later model pilot bearing as a substitute. Be warned that the pilot bearing will be less forgiving about any bellhousing missalignment as compared to a bushing and the bearings can not be "hydraulicaly" removed later. It requires a realy good puller to remove the bearing if they ever fail. Bushings just pop out with grease, hammer and a wooden stick.

-Mark.

[Stingr69]

Stinger,

Can you feel a vibration in the clutch pedal when the galling noise appears?

If you have that then I would be looking closely at the throwout bearing as the other possible culprit. A bad throwout bearing will have some of the same symptioms as a galling pilot bushing. Bad sounds with the pedal on the floor. I did not have the pedal vibration problem but it was something you could lightly feel in the set of your pants. Mostly I could hear an awefull sound when the car was running, not rolling, and in gear with the pedal down.

I feel my throwout bearing is fine as it has low miles and still feels very smooth. It might go back in there.

-Mark.