Clutch woes - pilot bearing ??

[Hubert]

What is the deal with the clutches on the 6.5 / NV4500. Is it a poor design on the pilot shaft bearing or input shaft of the transmission. Or a cheap clutch?
I am having a clutch release problem. I have a 3-4 month old master cylinder and the pedal feels pretty good but the clutch doesn't want to release especially in higher gears. Might be a pilot bearing alignment problem???

Is there a recommended better fix than OEM set up? I think it went out at 60,000 miles originally and now its acting up again after another 60,000 miles! Dang it should last a lot longer than that!!!

I have the normal NV4500 groans and everything feels pretty good/normal no excessive vibration etc. Sometimes a little shudder on launch but not too bad. I am going to try bleeding the slave anything else I can do easily to help it?

Besides RPM matching anything else help the clutch workings?

[a5150nut]

Don't over tighten the bleed screw. The slave cylinder is plastic. As for the pilot bearing, use the earlier model bronze bushing for the gas motor.

Make shure your trans to bell houseing bolts are tight, especialy the two on top. Had mine lossen up and ate up the thougout bearing.

[Turbo Al]

Well first I have heard of this type of problem.
I get about 60-70,000 miles out of my clutches but I am perhaps a little hard on them (offroad).
1. As stated be VERY GENTLE tightening the bleed screw--it is a tappered fit not a tight as you can go fit--just pull the screw out and look at it and you will understand.
2. Also as stated put a solid brass/bronse pilot bushing in from a 1970's era 350.
3. I have not worked on a 97 (just the 1993) and realize that they have a different setup as far as the pivot ball and throwout arm go BUT you are overdue for those parts.
4. Yes the pilot bearing is a weak point--to get it out fill the cavity behind it with grease, put a shaft in the hole, and hit it -- the hydralic pressure should just pop it out.

Good luck
Al

[catmandoo]

i lost a spring in my clutch disc about a year and a half ago and it locked up my clutch,and when i took it apart the pilot bearing was in cinders,this was before i was on this site and i used the bearing again,well it's pushing right at 90,000 miles on this clutch and still working good.but the next time it goes,it will be getting a bushing.by the way truck just hit 455,000 miles another 9 months and it should be the big 50 0,000

[StephenA]

I had a release problem and when I R&Red the clutch I found that several of the dual mass flywheel ball bearings had come out and lodged between the clutch plate and the flywheel/pressure plate. It made an awful racket right before that. Do you have the dual or single mass flywheel? I found a used single mass on ebay for $50 which looked perfect against a straight edgeand only needed .007 turning on the facing. They are kinda rare, but it beats the $400+ price of new one. PS- always replace the ball stud, no matter how good it looks- it's cheap and can blow out your hydraulic seals if it's worn.
;-D

[Hubert]

I have started disassembling little stuff in the evenings. Its going to take me several days to get it torn down. I am not a real mechanic.

There are no real alternatives as I see it for the mating of the 6.5 to the NV4500 with factory bolt up. From what I have been told & read. Someone straighten me out before I waste money but ....

LUK makes the OEM unit. They do not offer a pro gold series for the 6.5.

The flywheel: Dual Mass switched to solid during the 96 production year. So I assume I have a solid.
Southbend recommended change to a dual mass flywheel.
Dial-a-clutch recommended a solid (factory setup)
Both offer the bronze pilot bushing.

I was told Centerforce nor anyone else makes a high performance pressure plate Most alter LUK's or a copy of LUK's. The factory master cylinder/ internal concentric slave cylinder won't hold up to a heavier PP actuation. ( I don't want a heavier pedal anyway.)

After that its sounds like brand loyalty and $$$ Centerforce and Southbend offer aftermarket clutch discs but OEM, Centerforce, or Southbend have a lot of springs for the rigid flywheel and thats the weak link (more components to fail and I guess weak center section).

After tear down I will make a final discision but am leaning towards a LUK kit with bronze bushing.

Comments suggestions anyone.

[Turbo Al]

Aww the dual mass -- solid flywheel debate goes on :eek:
You should have a solid flywheel -- if nobody has tinkered with it yet -- and since it is the factory set-up it was done correctly and you should NOT have to change it out and go to a dual-mass -- I certainly wouldn't and I happen to like the dual mass setup (in my 1993).

I do not like the massive array of spings on the solid flywheel but they do seem to work well when properly setup. Pay close attention to the torqueing of the pressure plate -- torque them the same method as a wheel, a VERY common mistake is torqueing them in a circle one after each other this does not work because of the resistance of the springs in the pressure plate. I like to go up in small increments untill the final torque is achieved.

Acctually you can give the pressure plate coming out a quick torque check and I bet one side (leg) will be loose. This causes uneven pressure plate wear.
Al

[Hubert]

I have my truck torn down (a heck of a job) and the center section of the Luk clutch is broken. One of the inner springs in the disc is gone (solid flywheel) and others are broken and scratched. The pilot bearing was torn up and the rolls & inner race are gone. It messed up the pilot area of the input shaft. The center section that was coming apart was rubbing the pressure plate too.

I think this same thing happened at ~60,000 miles to the original owner. Now at 120K its the 2nd time.

This appears to be a common failure I have read from other posts. Its not the clutch wearing out or a slipping problem its the center section thats weak and I guess fatigues and breaks.

After seeing the damage I am a little leary of another LUK clutch. Is the center section of the Centerforce clutch disc any better????? Or any alternatives.

I see the bronze bushing is recommended over the needle bearing by many. What breaks first the pilot bearing and then the center of the disc or does the center section breaking then tear up the pilot bearing?

Also how to get the pilot bearing out. Grease it full then use a rod same size as the diameter of whats left of outer race and smack it out with the hydraulic action. Not sure thats going to work the outer race is pretty boogered up. I guess I can try and find a reversed hammer thingy. Any other options?

[Turbo Al]

On my second clutch (dual mass) it was the pilot bearing that gave up first then scored the pilot shaft -- clutch was fine.
Replaced the pilot shaft with a rebuilt one for about $100 plus the old shaft for a core. They just machine off the damage and put a speedy sleeve on.
Al

[catmandoo]

when my clutch went,i got one right thru ac/delco,and in the book they listed 2,standard,and heavy duty.well i figured i just had the standard,so in it went,and it sounded like every bearing in the transmission was flying apart,so i took it back out and got the heavy duty,the difference between them was the heavy duty had a plastic bushing around the center hub of the disc,this quieted it right up,

[Hubert]

catmando,

This clutch had a piece of plastic inside the stamping of the center section that look like a bushing of sorts. It looks like it helps absorb some of the flex and shock of the inner part of the center section to the outer portion.

I don't know the center section just looks like a cheap stamping that is spot welded up. A couple of spacer segments were broke and fell out when I had it taken apart. Southbend clutch looks more solid but I have only seen a photo and they are pricey. I can't tell from the centerforce pics which looks better.

Maybe if its the pilot bearing breaking first a solid bronze bushing may be an improvement. I just don't want to do this again!

[JohnC]

The dual mass flywheel absorbs some of the power pulses of the crankshaft. The solid flywheel passes them through, so the next thing in line is the clutch disk center....

[catmandoo]

i myself wondered just how that plastic (bushing) is supposed to hold up for more then 5000 miles,but i have 90,000 on it now and it's still working good so i guess i can't complain too much.