vibration in clutch pedal coming from balancer?

[timzak]

I just got my '94 Mustang GT back from Aamco transmissions. I took it in because of a buzzing vibration in the clutch pedal between 1500-2000 rpm that would go away if you rested your foot on the pedal. They said the clutch and tranny are fine, the buzzing is traveling down to the clutch pedal from one of the pulleys and causing the clutch pedal to vibrate. I got my car back no charge (cool).

Now, about 2500 miles ago I had my balancer replaced (typical balancer going bad in the '94-'95 Mustang GTs) with an Autozone model. It still looks fine. Could my old balancer have damaged the shaft to the point of causing this buzzing vibration? Could the new balancer installation been done improperly?

The car is a weekend driver, so I'm not going to drive it anymore until I fix the problem. But I'd like some opinions from you guys on what the problem could be and how much damage has already been done.

Any help appreciated.

[ September 16, 2003, 11:46 PM: Message edited by: timzak ]

 

[got boost?]

be more descriptive as to the noise/vibration, what is the frequency? is it happening only in one gear? did this start happening before/after the balancer was replaced?

 

[timzak]

quote:

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Originally posted by got boost?:
be more descriptive as to the noise/vibration, what is the frequency? is it happening only in one gear? did this start happening before/after the balancer was replaced?

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Thanks for the reply. "Buzzing" is about as descriptive as I can get. It's like a rapid-fire clicking (ie, no whining, screeching or other similar sounds).

It is most easily heard in 1st and 2nd gear, but I think it happens in all gears, but it's harder to hear in gears 3-5 because by that point vehicle speed is such that road noise is masking it. Only in the 1500-2000 rpm range. With the stereo off and windows closed you can easily hear it start once you hit about 1500, and die out once you pass 2000. If I cruise anywhere between that range in 1st or 2nd gear, then lightly rest my foot on the clutch (not push it in, just the weight of my foot on it), the sound goes away instantly. If I remove my foot from the clutch, the sound comes back.

I've been given a number of opinions already, most of them are of the "wait and see if it gets worse" variety. Someone suggested it might be normal clutch pedal vibration due to age of the car (9 years). Someone else said the new balancer might be slightly out of spec, or weighted slightly different than the original. Someone else insisted the problem is either in the clutch or flywheel area and is related to flywheel balancing issues. As you can see, the suggestions pretty much cover the gamut.

Hopefully this is descriptive enough to help you out, goot boost?

Thanks.

 

[BOBISTHEOILGUY]

Any time you just rest your foot lightly on the clutch, what you are doing is allowing the weight to press on the thow out bearing only, which barely rides against the clutch pressure plates fingers. When you do this, you are basicly putting a light pressure on the bearing. The fingers on the clutch pressure plate isn't affected as it takes pressure to get them to move. That IMO would mean and is very common, particularly in varing weather condtions/hot and cold, the thow out bearing is making your noise. Very common and will not actually hurt anything at this stage. What will happen is that it will eventually get louder as the wear will get worse. The other thing is that it will become more noticable in cooler weather. Has your weather become slightly cooler? notice it more on some days than others?. This is just another indicator for bearing wear. Also, vibration can come from the pilot bearing. Ok, it's not really a bearing as you'd know it, it's a bushing that is pushed into the back of the engine block which is where the shaft from the transmission is pushed into, so that it holds the shaft in place. This should be replaced anytime a clutch is replaced as it will wear and allow for vibration as well.

To replace either bearing/bushing, you might as well replace both at the same time. Heck, down that far, put in another pressure plate, and clutch. You'll have less than 100.00 bucks into it if you replace it yourself. That way, it's all new and no worries.
heres a basic diagram on the internals on how a clutch works.
How a clutch works

[ September 18, 2003, 11:09 AM: Message edited by: BOBISTHEOILGUY ]

 

[timzak]

Sweet, thanks Bob!

The car is driven less than 200 miles a month on average, so I won't sweat it at this point.

BTW, I'm still not entirely convinced it's NOT coming from somewhere else. Why would Aamco turn away an opportunity to make some money if they weren't reasonably sure the problem wasn't clutch related?

I'll keep a close eye on the noise levels and if they relate to weather and driving conditions. Thanks again, Bob.

Tim

 

[BOBISTHEOILGUY]

A noise such as you describe is common from other areas but the dead give a way is the fact it disappears when you rest your foot on the throw out bearing(clutch pedal). If not for that, it could be anything from the speedometer cable spinning in the cable housing, Wheel bearings to drive line problems.

But, again, clutch touched, it goes away, got to be the bearing. Only thing you're doing to it to cause it to quite down.

I hoped that picture helps demonstrate how it works.

 

[timzak]

quote:

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Originally posted by BOBISTHEOILGUY:
A noise such as you describe is common from other areas but the dead give a way is the fact it disappears when you rest your foot on the throw out bearing(clutch pedal). If not for that, it could be anything from the speedometer cable spinning in the cable housing, Wheel bearings to drive line problems.

But, again, clutch touched, it goes away, got to be the bearing. Only thing you're doing to it to cause it to quite down.

I hoped that picture helps demonstrate how it works.

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Yes Bob, the picture did help, thanks. One last question, would it help extend bearing life if I drove with my foot resting on the clutch between shifts?

 

[BOBISTHEOILGUY]

No sir!. The bearing is just floating with no load so no real friction is occuring. Chances are, the bearing has no lubrication in there or very limited amount, that's why most give out, being exposed to the heat and water intrusion that gets splashed up in normal use.

to keep pressure on it, will cause it to run constantly, and that will create more heat and reduce the bearing life as well. Being that you live in the outskirts of LA, where it stays warm, I'd bet you'll have a while before it really gets bad. Especially since you only use it on the side with min driving. If me, just make a little side job of it, taking your time and drop the trannie, and pull the clutch assb out, and replace with all new. I bet you'd find it fun and interesting.

BTW, forgot to explain. In the picture I supplied you, notice the bearing is all the time up against the little forks (what they call diaphragm Spring). This is what you would be doing if you keep your foot on the pedal. The bearing normally will have a slight little play in it. This play is the distance of where your clutch pedal travels from the top, until you feel it touch. (the free travel play on the pedal). This is where you'd adjust the free travel and you always want some play where the throw out is not up against the clutch all the time as you can adjust it to ride all the time, which will cause it to wear out prematurely.