So a little bit of a puzzler for you guys. I'm not sure about what kind of car this is, though I will get that info for you as soon as I know.

My coworker got his vehicle's clutch replaced at a local performance shop (a good one, where I have all my work done). Afterwards, his clutch pedal has what he described as 'vibrated a lot and was sticky'.

He brought it back to the shop, where they removed the transmission, inspected everything, and replaced the throw-out bearing as a 'just in case'. After he got the car back, the vibration and stickiness was gone, though the pedal had a very high engagement point. Over this weekend, the stickiness and vibrations seem to have come back!

So, what ideas do you guys have?

EDIT TO ADD: It is a 2006 Mitsubishi Evo IX MR. Thanks in advance!



Edited 1 time(s). Last edit was 2009:06:29:14:08:53.

" by “stickiness”, I mean that the clutch pedal sticks to the floor even after I lift my foot. So between gear shifts, when I pick up my foot, the pedal stays down for a split second, then gets unstuck. Then I can feel it slap the bottom of my foot."

you need to bleed it some more.

This is a problem that wasn't there with the old clutch, and they didn't break the lines open to install the new clutch, so no additional air would have gotten in.

My 'seat of the pants' guess is the Clutch Master cylinder is starting to fail, and has let air into the system, but I sort of want confirmation before I play Encyclopedia Brown.

I wouldn't think a failing MC would cause pedal vibration, though. The vibration and the pedal not coming back up immediately .. might the pressure plate have issues? unbalanced or a bad spring or something? Just a wild guess .. it might explain both behaviors.

Mike

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Charlottesville, Va.

1983 280ZXT in a million little ziplock bags.

I'm in agreement with cville-280zxt .
Even a good shop can get a defective part once in a while.
Was the throwout bearing the shop put in a second new one. They did put a new one in the first go round , right?
This really sounds like something is not lined up right or is warped or the parts aren't the right ones for the car.The fingers on the pressure plate may be the wrong thickness and they are compensating with a different throw out bearing. At first I was thinking pilot bearing for the vibration but that wouldn't cause the pedal problem.Unless the pedal and the vibration are caused by two different conditions.

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western Nebraska
1979 280zx coupe parts car
1980 280ZX coupe
1980 280zx 2+2 gone to z heaven
1991 maxima
2001 maxima
2002 maxima
1994 F150 4x4 van works custom pickup


Where are the old guys?
Sometimes you don't miss them until they're gone!
Nobody to whine and cry to-
I kept telling you not to poke the bear
Better get an FSM, learn how to read it and keep it handy children...

Just a thought: If the engagement is so high (and the master cylinder piston is being pushed in a longer stroke), is the fork/thrust bearing casing "over-travelling" and getting hung up on the ends of the fingers in any way?

Try adjusting the pedal engagement down?

Or the pivot or fork worn and the fork ending up off-center of the bearing upon full engagement and the back force by the bearing on the misaligned fork on "release" is pushing the fork back on the pivot at an odd, albeit small, angle to cause it to bind temporarily on the pivot. (And if worn is the fork making contact with the bearing while disengaged, causing vibrating pedal? In addition to which the fork spring may be weak.)

This may not make any sense, but Keep It Simple is not my mantra.

SO, I was told that the previous clutch failed pretty catastrophically. It had warped the flywheel, threw a few of the anti-vibration clips, and wore the clutch all the way down. Apparently it was pretty screwed!

The shop seems to think that everything is still in spec, but I'll let them know to take another look at the fork. Thanks guys, and keep the ideas coming!

"It had warped the flywheel."
If the flywheel warped upon catastrophic failure, I assume they checked the crank flange for runout damage.

Yep, they said they did both times.

They are going to change the CMC to fix the sticking.

As for the vibration, I talked to the owner a bit more, and it seems he has been riding the clutch (hence the failure), and the vibration he feels is just when it starts to engage. Basically, he's driving with the clutch pedal barely engaged, and is feeling the throwout bearing. It is fine for the rest of the time.

Pretty simple, huh? As I said KISS is not my mantra. ;)

It is weird, but the guy still won't accept that it is the problem, since it apparently didn't do it before. He went from 'annoying' to 'd-bag' as soon as I mentioned he was riding the clutch, so I'm not helping anymore.

He'll just have to burn out another clutch. Human nature: hardheaded is as hardheaded stays.