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The 3000 Forum

Clutch pedal vibration

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bipbip Juan Luis REDO
Vinaros, Vinaros, Spain   ESP
In reply to # 207900 by RAC68 Hi All,

I must admit I am a little surprised that others feel hydraulic flutter could cause peddle vibration. I do feel a misaligned or broken pressure plate arm could cause the release bearing to vibrate but am unsure this vibration would be transmitted through the slave and master cylinder links and passed to be felt in the peddle. Keep in mind that, although Juan has had shifting difficulties recently, I would expect the amplitude of the vibration emanating from the pressure-plate/release-bearing would be far short of that needed to overcome the fluid reservoir buffers of both slave and master cylinder to appear in the peddle.

However, I have heard where a fluids harmonic amplitude can increase with frequency so I wonder if this is not happening here and wonder if a change of hydraulic fluid would eliminate peddle vibration? Juan, what fluid are you using in your hydraulic clutch system (master/slave)? Has the fluid been changed recently?

All the best,
Ray(64BJ8P1)

Hello Ray,
I have not changed the cluth hydraulic fluid expressly but when change the hose. I have the original single bottle for brake and clutch and I use FERODO DOT 5.1, I think the best one.
Regards,
Juan Luis

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cpcooper Craig Cooper
Chico, CA, USA   USA
I think it's plausible movement of an out of true collar on the pressure plate rattling against the release bearing could transmit back through the slave and master cylinders to the clutch pedal. The master cylinder forces fluid through the line to move the slave cylinder, so why not the reverse? If I were to tap the end of your clutch arm with a hammer, moving the slave piston ever so slightly, wouldn't you feel it if your foot was on the pedal? Here, the out of true collar is whacking the release bearing maybe 50 times per second and my guess is that's the source of the vibration. It should go away with pressure on the clutch as the release bearing will be steadying it. I know this doesn't account for the shifting difficulties, but since that is only noted from fourth to third, I can't see it being related to a clutch issue, such as dragging or not fully releasing, as that would cause problems third to second and certainly neutral to any gear. So, why is the collar on the pressure plate not running true on two consecutive new pressure plates? I would start with checking the clutch mount surface on the flywheel with a dial indicator while slowly turning the crankshaft by hand. Seems very unlikely the surface wouldn't be true, but it's possible the flywheel is not correctly seated on the crankshaft flange; improper fit, or foreign material on the mating surfaces. If it's aluminum, could it have been damaged when the ring gear was installed? If the flywheel surface checks out OK, I'd mount the clutch and check the release collar the same way with the dial indicator and see if that runs true. Take a hard look at your old release bearing to see if there are any clues (I assume you're replacing this along with the other clutch parts). Next, the release arm/clutch fork is a possibility. I had a 100 clutch that rattled like yours and the release arm bushings were worn. I replaced them and the pressure plate at the same time, which resolved the problem, but you have done as much and your problem persists. Any chance your clutch arm is bent, cracked, worn where it cradles the ears on the release bearing such that the bearing doesn't meet squarely with the surface on the collar on the pressure plate? There is a smoking gun here somewhere, and with patience you'll find it.

bipbip Juan Luis REDO
Vinaros, Vinaros, Spain   ESP
Hello,

Thank you for your reasoning. In reference to the shifting difficulties, from fourth to third, that could be explained because at fourth it's when the vibration in hard because more speed and revolutions. On fact if a let that the car down speed, I can reduce directly without double clutch.

Summary:

- First check not only the mounts engine and gearbox, also the mount welds and frame.

If all is right, we will have to take out the geabox and cluth.
- Check orientation clutch. I cannot rule out.
- Check old release bearing to see if there are any clues. Sure!
- Check flywheel is not correctly seated: that was checked last time and we thought that we have found the origen, but the problem didn't disappear. We check it again.
- Check flywheel surface. That could be also a reason!! as you say it was manipuled to install the ring and could be damaged. I think also in the possibility to buy another one, I don't want to make this again and work is more expensive than parts.
- If all right, balance flywheel with ring and clutch.
- check clutch arm: bent, cracked, worn where it cradles the ears on the release bearing.
- Intall new bush and shaft arm. Nwe pilot bushing.
- New hose

I will inform you.

Juan

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cpcooper Craig Cooper
Chico, CA, USA   USA
Juan: The problem being the most pronounced at higher speeds is a huge clue.

Does the car have to be moving to create the vibration? Or, can you make it vibrate by reving the engine with the car stationary? If you were to drive 60 mph, put the transmission in neutral, and take your foot off the gas would it still vibrate?

A vibration caused by a clutch for flywheel would increase with engine speed, so it would feel about the same at a given RPM in any gear. If your vibration gets worse the faster the car goes, regardless of what gear you are in or engine RPM, it’s probably not the clutch or flywheel.

When the transmission was out the first time, was the driveshaft serviced? Possibly universal joints replaced? Any chance the driveshaft sliding yoke was removed, then put back together out of sync with the rear yoke? I also wondering if someone could’ve taken a shortcut when removing driveshaft, parted it at the sliding yoke, then got it back on in the wrong place. It is very important that the yokes on the two ends of the driveshaft are exactly in line with each other. The driveshaft could vibrate violently if they are out of sync.

bipbip Juan Luis REDO
Vinaros, Vinaros, Spain   ESP
In reply to # 207931 by cpcooper Juan: The problem being the most pronounced at higher speeds is a huge clue.

Does the car have to be moving to create the vibration? Or, can you make it vibrate by reving the engine with the car stationary? If you were to drive 60 mph, put the transmission in neutral, and take your foot off the gas would it still vibrate?

A vibration caused by a clutch for flywheel would increase with engine speed, so it would feel about the same at a given RPM in any gear. If your vibration gets worse the faster the car goes, regardless of what gear you are in or engine RPM, it’s probably not the clutch or flywheel.

When the transmission was out the first time, was the driveshaft serviced? Possibly universal joints replaced? Any chance the driveshaft sliding yoke was removed, then put back together out of sync with the rear yoke? I also wondering if someone could’ve taken a shortcut when removing driveshaft, parted it at the sliding yoke, then got it back on in the wrong place. It is very important that the yokes on the two ends of the driveshaft are exactly in line with each other. The driveshaft could vibrate violently if they are out of sync.
Hello,
Hello Coorper,
No, the vibration go and down with the engine speed, so ti comes from release beraing / cluth / flywheel.
I think that when I reduce from 4th to 3th is when the engine takes more rpm. But when I changed the clutch and the vibration was almos not noticeable, I had not problem to reduce from 4th to 3th, and later, with more vibration, I need to make double clutch.
Happy new year!

bipbip Juan Luis REDO
Vinaros, Vinaros, Spain   ESP
Hello,

We were checking in the workshop and we did'nt see any problem with mounts, frames...

We noticed that in the arm cluch the vibration is noticed. We are going to install a spring to take away the release bearing from the cover assy when cluth is not pressed, so at this moment the vibration is all time, so the bearing is touching the cover.

But the most important: we found the old clutch and there is important observation (see photos). It had only 5.000 milles aprox.





As you can see, the mark left by the release bearing, is not centered with respect to the hole cover assy cluth. I also remember that the release bearing was not evenly worn. So the pearing is not pushing off-center and sideways. I think that this could be the reason of vibration. What do you think? why this happens?

I remember that when installing the bearing I was thinking about to check if the release bering is pushing properly, but how to check this? you cannot see when you mount the bell.

Thank you by help!!!

Juan

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