Klondike

My LT4 started making a nasty noise when I started it the other day. When I pressed the pedal all the way down to start the car, it made a loud metallic noise when the starter engaged. It stopped as soon as the engine fired and I let the clutch pedal out. When I pressed the pedal down again to put it in gear it made the noise again when the pedal got close to the full down position. When I let up a little it stops. I can shift OK as long as I don't push too far down with the pedal. I'm familiar with how clutches work, but have never been into one in a C4
Best I can figure is the throwout lever is scraping on the back of the pressure plate. Is that even possible, and what has changed to make that happen? I'm not hard on clutches at all and never speed shift or slip the clutch. Is this something that can be adjusted or did something break? Am I looking at replacement of the whole DMF, clutch and pressure plate?

Impala Balko

Does it sound like this (the noise in the video that sounds like a jack hammer appears when the clutch is pressed to the floor) now what was causing this was the clutch fork was hyper extending and rubbing against the pressure plate, which was a result of the pivot stud backing out. All i had to do was pull the tranny and tighten down the pivot stud... i even put a dab of blue locktite to keep it from backing out again... There are many write ups on how to do this if you search for it you may even find my thread with all the advice i got

cv67

Its the fork hitting the PP

lt4obsesses

I know that sound all too well. You need a new pivot stud, and possibly a clutch fork. Try bill@ZFdoc and see if he can put you in the right direction, or Jim Jandik at powertorquesystems.com, he may have a lead also as to where to find one.

Klondike

Yep,you guys nailed that sound. Not a nice one at all. Going to Bowling Green in Aug. and wondering if it will fall apart before then? Does that get progressively worse until catastrophic failure or is it just an annoyance till I get around to it?
If I've got to pull the trans, it's going to get a steel flywheel and new clutch like a Spec (sp). Don't want to have to go right back in there for a Dual Mass flywheel failure after I just did a pivot.

Impala Balko

Mine got progressively worse until I did it... If I were you I wouldn't drive it until that is taken care of.... With mine I got lucky and there was basically no damage just a couple scrapes on the pressure plate but from what I understand the forks and pivot studs can be tough to come by

lt4obsesses

you definitely want to fix this asap. First, it's causing damage to the pressure plate and the fork. In short order the fork could break or at least begin to bind, if it binds completely you won't be able to start the car. Worse, if it binds while you're driving, there is a litany of things that could/will be damaged.

When you do go in for the fix, I recommend going ahead and replaceing your slave, and probably the master too. This has over extension has been going on for awhile now, and it has probably taken it's toll on the hydraulics. Wouldn't suprise me if your slave has already started to leak.

Firewalker11

I too had this problem with the fork hitting the pressure plate. Mine was as a result of a new clutch install that was not torqued properly. Dealership that did the work wasn't happy about it but they fixed it on their dime (as they should have) and it has been all quiet since.

Klondike

Talked to friend of mine in the local club that has done dozens of C4 clutches. It is most probable that the clutch fork is bent. I've always wondered what was the stroke limiter on these clutches; still don't really know. What I think could have happened is my starter safety switch (on the pedal I assume) is out of adjustment. When I went to start the car, I bottomed out the stroke and when the switch intermittently engaged, I shoved the pedal down harder and bent the fork.
Going to do some more reading about clutch/flywheel preferences till I make my mind up on a kit and probably put in a hydraulic throwout brg. Might be able to recoup some of my costs by selling the dual mass if it looks good when it comes out. It still works good, so somebody might want it, even if it is used.