Vibration in clutch pedal when engaging/disengaging

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mshanno1
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Vibration in clutch pedal when engaging/disengaging

Postby mshanno1 » Mon Jan 09, 2012 5:56 pm

Most of the time when I press or release the clutch pedal, the pedal itself is smooth; however, whenever I shift to 3rd gear or higher with higher RPMs (4k+), I feel a slight vibration in the clutch when engaging/disengaging. The pedal itself isn't shaking, but its like I can feel the RPMs in the pedal. I feels like I am doing something incorrectly. I had my girlfriend drive my car as I described (higher RPMs) because she is experienced with MTs, and she states that she doesn't feel anything. Any ideas if this is normal?

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bk7794
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Re: Vibration in clutch pedal when engaging/disengaging

Postby bk7794 » Mon Jan 09, 2012 11:35 pm

I get that sometimes...its like a shudder correct?

I think mine is due to hotspots on my flywheel.
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theholycow
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Re: Vibration in clutch pedal when engaging/disengaging

Postby theholycow » Tue Jan 10, 2012 7:47 am

I could swear in some old pre-hydraulic-clutch vehicles I've felt RPM in the clutch pedal, and that was part of why I had so much trouble re-learning when I got the 2008 VW and ended up on this forum...I was used to feeling that.
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Re: Vibration in clutch pedal when engaging/disengaging

Postby Rope-Pusher » Wed Jan 11, 2012 12:57 am

Fur the moss part, the clutch doan no if it's driving the wheels. Put the trans in Neutrals and bring yup the tach to 1000 rpm, then actuate the clutch pedal through the full stroke several times. Take it up another 200 rpm and try it again. Keep doing that until you mebbe find a particular rpm where the pedal comes alive. Keep going up-n-up by 200 rpms until mebbe it goes away, ....or gets wurst!

Has the phun started yetti?
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Re: Vibration in clutch pedal when engaging/disengaging

Postby mapman85 » Sun Apr 01, 2012 2:06 pm

This topic particularly interested me because I have noticed the same thing sometimes. Usually it happens on the 2>3 or 3>4 shifts at higher RPMs (>4000 or so). However, I've also started noticing it on occasion during calm, around-town driving. It seems inconsistent when I notice it though, but usually occurs while shifting (versus say, depressing the clutch when coming to a stop, or even during a launch for that matter). I've come up with these possible causes:

- It's a quirk of the car (a guy who helped me out after I bought it said it was one of the quirkier cars he had driven)
- Something is messed up or going bad (whether by me or the previous owners, but jeez, it only has 30,000 miles on it)
- I am doing something wrong/different on these shifts (different accelerator/clutch transition, shifting out of gear before clutch is fully depressed, ??)

Any additional thoughts? Something I should have checked out (it seems to have no effect on the quality of the shift though)? Thanks!
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bk7794
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Re: Vibration in clutch pedal when engaging/disengaging

Postby bk7794 » Sun Apr 01, 2012 3:44 pm

mapman85 wrote:This topic particularly interested me because I have noticed the same thing sometimes. Usually it happens on the 2>3 or 3>4 shifts at higher RPMs (>4000 or so). However, I've also started noticing it on occasion during calm, around-town driving. It seems inconsistent when I notice it though, but usually occurs while shifting (versus say, depressing the clutch when coming to a stop, or even during a launch for that matter). I've come up with these possible causes:

- It's a quirk of the car (a guy who helped me out after I bought it said it was one of the quirkier cars he had driven)
- Something is messed up or going bad (whether by me or the previous owners, but jeez, it only has 30,000 miles on it)
- I am doing something wrong/different on these shifts (different accelerator/clutch transition, shifting out of gear before clutch is fully depressed, ??)

Any additional thoughts? Something I should have checked out (it seems to have no effect on the quality of the shift though)? Thanks!


When I short shift and I try to accelerate in second by slipping the clutch (sort of like a launch) then I get a launch...Since I figured out about that I tried to stop doing that..it annoys me.
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Re: Vibration in clutch pedal when engaging/disengaging

Postby potownrob » Wed Apr 11, 2012 3:31 am

i've felt that before, especially when the rubber grip pad thing fell off the clutch pedal the other day :lol:
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Paul46
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Re: Vibration in clutch pedal when engaging/disengaging

Postby Paul46 » Wed Apr 20, 2016 3:20 pm

Hi mshanno1

I recently came across you post from 2012. I know it's been a while since you wrote it so here it is again:
[Most of the time when I press or release the clutch pedal, the pedal itself is smooth; however, whenever I shift to 3rd gear or higher with higher RPMs (4k+), I feel a slight vibration in the clutch when engaging/disengaging. The pedal itself isn't shaking, but its like I can feel the RPMs in the pedal. I feels like I am doing something incorrectly. I had my girlfriend drive my car as I described (higher RPMs) because she is experienced with MTs, and she states that she doesn't feel anything. Any ideas if this is normal? ]

I'm having exactly the same problem as you described. My BMW is 5 years old, I bought it 2 years ago and have had the problem for as long.
Could I ask if you ever found out the cause of the problem? And if so I would be grateful if you could explain what you discovered.
Thanks in advance.
Paul

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Re: Vibration in clutch pedal when engaging/disengaging

Postby Rope-Pusher » Wed Apr 20, 2016 11:21 pm

We used to run into something we called "Growl" when operating the clutch pedal at high rpm on a diesel engined vehicle. Some thoughts were that the end of the crankshaft was whipping around due to crankshaft bending and this was making the flywheel and clutch cover asembly oscillate. Really, it was more of an issue with cable clutch release systems. Hydraulic release systems use dampers to reduce the transmission of the pulses to the pedal.

I say "Some Thoughts", because manglement wanted a solution by the end of the meeting, no matter how little we really knew about the issue. They weren't willing to wait for a "root cause" study to be completed.
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Paul46
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Re: Vibration in clutch pedal when engaging/disengaging

Postby Paul46 » Sat Apr 23, 2016 4:59 am

Thank you Rope-Pusher,

Sounds like a thorough manglement.

I've recently had the DMFly replaced (Car had done 80,000 miles) to try and solve it but it hasn't made any real difference, in fact the 'RPM-grinding-mild-vibration', for want of another term, is probably more noticeable since.
So assuming this is caused by a bending crankshaft, is it something that could be fixed? i.e. is it something wrong with my 320d or all of them?

Regards

P

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Re: Vibration in clutch pedal when engaging/disengaging

Postby Rope-Pusher » Sat Apr 23, 2016 9:46 am

People like the dynamic smoothness of an in-line 6,
Image
but that long crankshaft is more "Bendy" than the short crankshaft of a opposed "boxer" 6.

(That was an issue even more-so with in-line 8 cylinder motors)

I wouldn't worry about it - it's not a durability problem.

Oh, also, engines are often designed with a net-thrust along the crankshaft toward the flywheel end.

When you push in the clutch pedal, and force is applied to the clutch cover diaphragm spring, this force opposes the thrust from the piston rods and it can move the crankshaft off the rear side of the thrust bearing and toward the front side of the thrust bearing. That noise could be the noise of the crankshaft shuttling from one side of that bearing to another as each piston rod shoves the crank back in opposition to the clutch release force shoving it forward.

If it didn't cost time and money, one, or two, could write a neat paper on what might be discovered about this.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"


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