Advice needed on vibrating clutch.

[Matlock1000]

Evening all,

I need some advice on a vibration I’m getting from a new clutch.

The engine on my minor died and not being able to afford a reconditioned engine I bought a second hand one. I had my local mechanic fit the second hand engine and at the same time fit a new clutch. All went well except I noticed a distinct vibration coming from the clutch pedal when I pressed it.

On inspection it was found that the thrust plate was not square. Thus when I pressed the clutch pedal down to the point where the release bearing made contact with the trust plate I would feel the vibration.

I know of others having similar problems with the springs in the clutch being knocked on assembly so I advised my mechanic of this and he removed the engine again, checked the clutch and then re-fitted the engine being extra careful. But we still had the vibration.

So I have now had the clutch removed and replaced with another new clutch, however the vibration is still there!! Obviously once in gear and with the clutch pedal released the vibration stops.

Is this vibration normal on minors?
(I don’t remember vibrations like this before the new clutch was fitted but then I hadn’t had her long before the problem with the engine.)

Any ideas on what is causing this?

Thanks in advance

Nath

[aupickup]

could be the thrust washers in the engine

[MarkyB]

See if the engine is shaking about when the clutch is depressed.
If the clutch plate if fitted the wrong way round things bind up and get noisy with the clutch down too.

[bmcecosse]

It's certainly not normal. I wonder if the flywheel is running true? Did you fit the fly from your old engine - or did it come with a fly? Did you fit a new bronze bush in the tail of the crank? This bush supports the first motion shaft from the gearbox - if it's not there -the 1st motion with the clutch plate on it's splines will flap about. I'm sorry to say - it looks like engine out again....

[robedney]

Just a thought, but is the throw-out bearing live or solid? I once had a car that I did a clutch on and replaced the existing throw out bearing -- which was solid carbon/graphite/something -- with a modern, live bearing. Depressing the clutch felt awful. I pulled the trans again, checked everything. The cure -- in the end -- was to track down a new solid throw out bearing and replace the live one. Shouldn't be that way, but the clutch felt and worked normally afterwards and got the car back on the road (and still was ten years later last I knew...).

The live bearings assumes more or less perfect alignment of everything, whilst the solid ones allow some room for deviation. Also, if it's a live bearing, it could be that the forks the hold the throw out bearing need to be centered to the pressure plate.

[Matlock1000]

Thank you all for your replies.
I’m not a mechanic, so please excuse my ignorance …..

Aupickup:
If it’s the thrust washers in the engine wouldn’t the vibration be continuous and not just when pressing the clutch down?

MarkyB:
I don’t recall noticing the engine shaking around when the clutch was depressed. I will check this again and report back.

Bmcecosse:
Have checked the flywheel and its running true (within about 3 thou). Didn’t fit a new bronze bush, to be honest didn’t check to see if it even had one at all. Would this bush really make a big enough difference to cause the pressure plate to be out of square and the vibration?

Robedney:
The old bearing was a “solid” type and it was replaced with a new solid type so I don’t think it’s the bearing but thanks for the advice.

[bmcecosse]

Well - the flywheel seems true enough - so yes, if there is no bush in the crank then the first motion shaft will be free to rattle around......

[rayofleamington]

I've never heard of a missing spigot bush giving a vibrating pedal.

The uneven pressure plate is usually a fault in the pressure plate itself - however the 'even-jness' of the realease pad depends also on the clutch plate being even.

It's fairly unlikely (but not impossible) that the clutch disk/lining iteself is uneven (thicker in one place than another). This would cause the symptoms you describe and is likely to make the clutch a bit more 'grabby/jerky' as well.

[bmcecosse]

It's an all NEW clutch - make unknown of course - so I would certainly hope it's in decent condition. The only unknown for me is the spigot bush - and it's supposed to be there to support that 1st motion shaft..... What symptoms would you associate with a missing spigot bush Ray ?

[Matlock1000]

BMC,
Is there anyway of checking if the bush is missing/ deteriorated before I remove the engine (again)?

RAY,
The second clutch was “checked” before it was installed because of the problems with the first one. Unfortunately to what extent it was “checked” I don’t know but no obvious problems were noted.

[Bazzalucas]

The last time I had my engine out I noted that there was no spigot bush. There was nothing about clutch action, vibration or trans/driveline noise to suggest that it was missing. I put one in as a matter of course, and the effect was....unnoticeable.

[bmcecosse]

I can't really think of a way to check without removing the engine...... Just how bad IS this vibration - severe - or just a sensation??

[MarkyB]

Also, can you feel it throughout the pedal travel or just at the end?

[Matlock1000]

Hi guys,

Sorry for the delay in replying but I have been visiting relatives over Christmas.

To give you some idea of the problem and the severity of the vibration I have taken some videos.

The first shows the bearing on the left with the pressure plate on the right and the engine being turned over by hand slowly. From this you should be able to see the miss alignment of the pressure plate to the clutch housing and the bearing.

http://youtu.be/hQsK0e9pjvs


In this second video the engine is running and the clutch is being pressed down to the point of contact with the pressure plate and then to its full travel. This should give you an idea of the severity of the vibration.

http://youtu.be/1fz9f2bizto


Hope you all had a good Christmas, and wishing you all the best for the New Year.

[bmcecosse]

That's hopeless - it has been smashed out of alignment during installation......don't run it!

[Matlock1000]

BMC
What do you mean "smashed" ??

The mechanics who put the engine in for me, assured me that they had put the engine in very carefully (especially as this was the 3rd or 4th time).

What would be causing that much miss-alignment?
Do you think that if the bush in the tail of the crank is missing it would give this much of miss-alignment?

[bmcecosse]

No that's not the bush! That's the operating 'platform' of the clutch pressure plate that has been smashed off centre when the engine was being fitted back on the gearbox. maybe it's just been dislodged from the supporting springs- no way to tell if there is any other damage till you take the engine back out.

[Bazzalucas]

I have to concur with BMC on this one. Ask me how I know!

[robedney]

I could be wrong about this, but: It looks as if one or more of the springs in the pressure plate have somehow been disabled -- broken, displaced, whatever. You can't keep running it like this -- something more expensive is likely to suffer. No mechanic could look at what you've shown in your videos and not immediately acknowledge the problem and understand that the engine's got to come out again. In fact, no good mechanic would let a car out of the shop like this. BMC is right. It's likely that whatever went wrong happened during the installation. I'd take the car to another mechanic -- one who works of MM's and does clutches -- and show them what you've shown in the videos. Get a second opinion, then go back to the people who took your money and make an issue of it. You've not been well treated! By the by, I would insist -- flatly insist -- on a new clutch kit at no additional charge -- including pressure plate, disk, throw-out bearing (or whatever you all call it) and -- while your at it -- a new pilot bushing. So you know, the worst thing a bad pilot bushing is likely to do is squeal like a stuck pig -- but it's all noise.

[mike.perry]

What is the original clutch unit like? I normally only replace the drive plate and thrust bearing unless the pressure plate is showing signs of wear