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Clutch pedal vibration

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

I have owned a 3000 Austin Healey last 10 years with a lot of good moments and 50.000 milles, but last years is a nightmare.

Two years ago I changed the clutch and took the opportunity to install a lightweight steering wheel. But since then the clutch pedal vibrates, it's a bit annoying.

The work shop does not give importance but also twice end up breaking the slave cylinder hose steel braid. They took out the box again, intalled other new clutch, they revised, new fork kit was installed so it had clearences (sure due to vibrations) and reassembled. The vibration was reduced a little bit, but not at all, I'm sure that this is not good for gearbox, which also scratches more than usual and double clutch is necessary from fourth to third.

I have not idea of the origin.

Thank you by help and Happy Christmas!!



Edited 2 time(s). Last edit at 2018-12-24 12:43 PM by bipbip.

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RAC68 Avatar
RAC68 Raymond Carbone
NJ, Jersey Shore, USA   USA
Hi Juan and Merry Christmas,

My first thought is to check for a broken or loose motor or transmission mount that is causing the drive train to misalign and vibrate. Also, I would check the frame for cracks that could also allow the drivetrain to misalign.

You mentioned replacing the original Steering wheel with a light weight version. I suspect you meant the Flywheel was replaced and, if all mounts are found to be in good condition, I expect the new Flywheel was not balanced, not mounted correctly, or the pilot bushing was warn or not installed.

Just my initial thoughts.
Joy to you and your Family on this Christmas day and have a Happy and Prosperous New Year,
Ray(64BJ8P1)



Edited 1 time(s). Last edit at 2018-12-25 09:53 AM by RAC68.

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

Thank you by your help!

We changed the clutch and flywheel and the pedal vibration appeared. After 3000 milles, the clutch begun to don't work properly, we changed again the clutch, and changed the gearbox mounts and cheked the engine ones. Chequed the flywheel, also the pilot bushing was replaced again.

The cracked frame could be a possibility so my frame is very tired (55 yeard old + intensive use last years), but the vibration only apperared after to change the flywheel and clutch, so the problem should be there.

I bought the lighted flywheel in AH Spares, so I think it was factory balanced. I think it was a mistake to change it, so probably the original one was balanced with the crank... but this could be the origen of this easily noticeable vibration? I have installed light flywheels in other cars with no problem.

The vibration is noticeable also without to touch the pedal, so the relesase bearing is touching the clutch. Is that normal?

Thank You!!

Juan

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RAC68 Avatar
RAC68 Raymond Carbone
NJ, Jersey Shore, USA   USA
Hi Juan,

Based on what you have added, I would have AH Spares verify that the lightened flywheel is, in fact, balanced and then reinstall the original to verify the problem does not remain and is not within the clutch, pressure plate, or flywheel. I appreciate this will be a pain but since the issue still needs to be corrected, you will need to determine whether the problem is within or outside of the flywheel/clutch/pressure-plate/release-bearing components.

You have indicated that the clutch pedal vibrates without being pressed. Keep in mind that the Healey's clutch pedal actuates a hydraulic master cylinder and the clutch fork/release-bearing is moved by the responding slave cylinder. As a result of the clutch actuation system using a hydraulic link, I find it doubtful, but possible, that physical clutch vibration will be transmitted through this hydraulic path from clutch/release-bearing to pedal. However, clutch vibration could be transmitted through vibration within the drive-train/clutch-housing and/or via hard contact between these components and the body area supporting the pedal itself.

Sorry I can't be more definitive,
Ray(64BJ8P1)

RAC68 Avatar
RAC68 Raymond Carbone
NJ, Jersey Shore, USA   USA
Juan,

You mentioned that your last disassembly showed no problems in the flywheel, clutch, pressure plate, or release bearing/fork but a little while later you were having difficulty with the operation of the clutch. Imbalanced components in this area will cause vibration and eventually component failure. A fracture of any pressure plate tines (fingers) pressed by the release bearing will cause the application/release of the clutch to be uneven and eventually cause it to break. This could cause quite a vibration of the drive train and allow it to come into hard contact with the trans enclosure.

Just another thought,
Ray(64BJ8P1)



Edited 1 time(s). Last edit at 2018-12-26 08:57 AM by RAC68.

NaDaDawgRacer John Jones
Waxhaw, NC, USA   USA
Just a thought, did you install the clutch disk in the proper orientation? Also most any good engine machine shop should be able to balance the new flywheel
John

petnatcar Avatar
petnatcar Silver Member Peter Carbone
Watertown, NY, USA   USA
Juan,

How old is the Flexible Line to the Clutch Slave Cylinder?

Like the Flexible Lines to the Brake Calipers these will fail over time and effect the brake performance.
This could be the problem if it's very old.

I'd replace that first.

If that doesn't help you may have to put the old Flywheel back in but
you can always lighten that one as was described in an article last week on this website.

Good luck,
Peter

RAC68 Avatar
RAC68 Raymond Carbone
NJ, Jersey Shore, USA   USA
Peter,

Juan did indicate that clutch operational problems had developed but did not go into any detail. If the flex tube does collapse, the slave cylinder will not actuate properly but I don't think it will cause the peddle to vibrate.

Since we have a hydraulically actuation soft link (including flex tubing) between release-bearing/folk and peddle, I doubt any vibration starting in the clutch would ever reach, or be felt, at/in the peddle. If anything, I expect Juan's clutch peddle is vibrating from a cause much more in hard contact, i.e. bell housing vibration (from a clutch component imbalance) transmitted through contact with peddle housing. This condition would only happen if an engine mount displacement or other mispositioned component has taken up what should be the open space (buffer) space that should be between the two hard components and would indicate more then one contributing issues.

Just my thoughts and Happy New year,
Ray(64BJ8P1)

petnatcar Avatar
petnatcar Silver Member Peter Carbone
Watertown, NY, USA   USA
Hi Ray,

I've never experienced a vibration like Juan has so I'm just shooting from the hip on this one but I
know those flexible hoses can cause problems if undetected.

It would be easier to change that hose instead of the Flywheel.

I'm thinking if the hose is blocked it may prevent the Slave Cylinder from releasing all the way
there by keeping some pressure on the Release Bearing which might cause a vibration.

It sounds to good to be that easy but ya never know...

Peter

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

Thank you to think about the problem and possible solltions.

Las time we changed the cluth (1.000 milles ago) we changed also the slave cilinder and the flexible hose. On fact, I think that like a consequence of vibration, the flexible hose was collapsed and the cluth didn't work properly. The pedal vibration comes of a pressure hit in the hidraulic clutch system, that arrive to the pedal. It´s like to push the cluth a lot of times at the inverse, so the hose is aged sooner.

Today AH spares answer me about the factory balanced flywheel question. They confirm me that it was balanced by they suggested me - without to talk them abpout the problem - that it's advisable to have the complete assembly balanced when the starer ring gear and clutch are fitted. That seems to be very coherent and we dind't do it.

So today I talk with the workshop mechanic and we decided:

- 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, and to install a new one clutch, now balanced all together. I will check the proper orientation of clutch. Unfortunately I can not find the original steering flywheel, I think I threw it away. I never throw anything but I'm tired of saving useless things, it was very heavy and I thought I will never need it. But as I said, I think it was a mistake to light the flywheel in this engine, I didn't noticed any improvement but a lot of problems. Perhaps in very performance cars, but not always will be better, I think.

I will inform you. Happy new year!

Juan

cpcooper Craig Cooper
Chico, CA, USA   USA
First of all... If you give up on that light flywheel, I'd love to buy it. I don't think that's your problem though. I think it is the pressure plate or clutch cover... Look at the one in the picture below. Think what would happen if the collar in the center that meets the surface of the release bearing is not running perfectly parallel to the surface of the flywheel. Since the bearing runs fairly close to that surface, if the collar is not running true, it seems it could rattle against the face of the release bearing and transmit vibration through the hydraulics and up into the pedal. I think a faulty pressure plate might also account for the difficulty downshifting from fourth to third, although if it were causing the clutch to drag you'd have a lot of other shifting issues. I think you are on the right track taking the flywheel and pressure plate to be balanced together. I would make sure it is a new pressure plate though.


Attachments:
Healey Clutch.jpg    39.5 KB
Healey Clutch.jpg

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

Exactly this " if the collar is not running true, it seems it could rattle against the face of the release bearing and transmit vibration through the hydraulics and up into the pedal" is what I think is happening. This is the reason of transmission of vibration to the pedal clutch but is this the reason or a conseqüence?

After 1.000 milles we changed again the clutch so we thougt that probably the pressure plate was faulty, as you indicate, but with all new compponents (clutch, plate, hoses, pilot buhing...) the problem is again.

When we changed the clutch, that area that you indicate, showed inappropriate wear.

Sorry with my poor English. I hope that you understand me.

Thank you!

cpcooper Craig Cooper
Chico, CA, USA   USA
Juan, your English is fine. I was going to try to reply in Spanish, but lost my courage! I think you should send me that light flywheel so I can install it in my car and I’ll let you know if I have the same problems. (Forgive me, a small joke)

You have an unusual set of problems that may not share a common cause. Reading through your posts again, I see:

Clutch pedal vibrates

First replacement clutch failed after about 1000 miles

Pressure plate release collar had abnormal wear

Shifting from fourth to third requires double clutching

Two steel braided hydraulic clutch hoses have failed

Work done so far:

New AH Spares light flywheel installed

Complete clutch assembly (disc, pressure plate,release bearing)

New release fork kit installed

New slave cylinder and flex hose installed

New gearbox mounts installed

Another new pressure plate installed

Is that everything? You’re right about the nightmare part, but it will be a great day for you when you solve the problem or, more likely, problems. There’s a lot of expertise and experience in this forum and someone here is going to know how to fix your car. Maybe it would help to start with questions back to you:

What was the initial reason for replacing the clutch and flywheel?

Was there any vibration before the work was done?

Was the entire clutch assembly replaced

What’s included in a “fork kit”?

Does the vibration change with light pressure on th clutch pedal?

Does it vibrate when the engine is reved in neutral? How about with the cutch pushed in? Any difference?

Any problems changing gears before the initial clutch and flywheel job?

Any problems shifting into first or reverse from neutral?

I could go on, but this should get us started. I have a couple of other ideas, but would like to know more first, and there are guys way smarter tan me here who will hopefully figure it out. What the heck makes a hydraulic clutch pedal rattle, destroys braided lines, and makes it hard to shift from fourth to third?

RAC68 Avatar
RAC68 Raymond Carbone
NJ, Jersey Shore, USA   USA
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)

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

you summarized well what happened.

I will try to answer your questions:

What was the initial reason for replacing the clutch and flywheel?
After a lot of milles without problems the clutch was spent. We were going to change only the cluth but ther was not stock of 10" clutches - my car is a BJ7 - I had to wait 2 months and the gearbox was already out, so I decided to change the flywheel to a 9'5" and instal a 9,5 kit clutch.

Was there any vibration before the work was done?
No.

Was the entire clutch assembly replaced
Yes, 2 times,

What’s included in a “fork kit”?
A new bush and new shaft, so due to vibrations it had clearances.

Does the vibration change with light pressure on th clutch pedal?
After change the cluch, the vibration is almost anappreciable, but with the use it increases. At the beginig only noticeable when you begin to push the pedal, later you can hear it and notice it when you put the foot on the pedal.

Does it vibrate when the engine is reved in neutral? Yes, all time. How about with the cutch pushed in? Any difference? When you are pushing the pedal - from middle to end - you don't notice it.

Any problems changing gears before the initial clutch and flywheel job? I think no, it was 3 years ago and I don't remeber well.

Any problems shifting into first or reverse from neutral? No specially.

I thank everyone for your interest!!

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