Throw out bearing wear

[c130]

I have a 1995 c2500 2wd extended cab with a 6.5TD and a NV4500 trans. I replaced the dual mass flywheel and transmission about 6,000 miles ago due to hard shifting when the pilot bushing let go.
When I replaced the flywheel I up graded the Transmission to a 2000 nv4500 w/ dampner and a 2000 bell housing and throwout bearing.
Now the problem. When I push in the clutch pedal I get a heavy vibration in the pedal along with a loud roar. I replaced the new throwout bearing and found it to be all wobblly. Not nice and tight like it had started life 3000 miles earlyer. When I replaced the factoy throwout bearing I retorqued the flywheel and also found no wear on the bronze pilot bushing. I am about to replace another throwout bearing because the pedal vibration is getting bad.
Any one have any good ideals what the problem is?
Thanking you in advance.
Stewy

[NH2112]

Well if it's anything like the throwout bearing in an SM465 then the problem is a cheesy throwout bearing! It just seems to me that a slot or groove you have to pack with grease (a la SM465 T.O. bearing) would be just as likely to squirt it out or let it run out when it's hot. I think the next one I replace is going to have an experimental piece of the smallest brake line I can find brazed to it (or maybe some nylon tube for an oil pressure gauge stuck into a slightly undersize hole) that I can carefully pump a shot or 3 of grease into with a needle. The B-W trannies IH used in Scouts used a big-truck-style bearing with a grease zerk accessed through an inspection cover on the bottom of the bellhousing (you also checked free travel here.) Why GM couldn't use this setup, I don't know!

The NVG4500 slave cylinder is incorporated into the throwout bearing (or vice versa) and it rides on the input bearing retainer, correct? I'm wondering if the slave cylinder might be pushing a little off-center and causing the bearing to hit the diaphragm cockeyed.

[Chris Hinds]

This is a long shot, but something to consider...
First, a 2000 trans and bellhousing fit a truck with a single piece flywheel... If you are using a DMF, could the input could be ending up short of the pilot bearing?? That will cause a horrible crunching rattle when you disengage the clutch and the input shaft gets rattled around.

Just something to check.
C

[c130]

NH2112 and Mr.Hinds, thank you for your help. I'm sorry that I miss lead you in my original posting when I only said I replaced the flywheel. I should have clarified that I replaced the flywheel with a solid replacement flywheel from GM.
Here soon when I pull the tranny out I'll check the throw out bearing mount for "cockeyedness".
Thanks again, and I'll let you know what I find.

[cruzer]

Also look at the forks/fingers on the pressure plate. See if they are all the same height. Does it have a lot of little fingers or just 3? Sometimes the 3 fingers are adjustable, so you can make them all the same height. Don't know if GM's are like that. Just a thought.