mk1-forum.net

I took the mini out last night. It was fine when I left but over 20 miles developed a pretty nasty noise when the clutch is pressed, I know it's impossible to diagnose noises over the net, but just interested in peoples ideas.

When the clutch is depressed, it disengages and re-engages correctly.
I can feel a 'roughness' through the pedal and it has started to make a graunch. This happens in any gear or neutral.
In gear it drives perfectly and I can't feel any vibration. The graunch/roughness starts as soon as the clutch starts to disengage.
I have full oil pressure etc.

The engine and gearbox were fully rebuilt about 4 years ago and have done 2.5k since.

The things that I can think of are that the clutch release bearing has broken up (it has a grey diaphragm clutch in it so it is under more load and I suspect that the low mileage doesn't do it any good!).
The flywheel could have come loose, but I suspect not as I would expect to know about this when driving it.
The thrusts could have gone, but again I suspect not as I have full oil pressure and it was rebuilt so recently.
The clutch could be breaking up, but I doubt it would happen in such a short mileage or happen over 20 miles or so.
I don't think it can be idler gears as it happens with the clutch disengaged.

.... any other ideas?

I will have to investigate at the weekend but am interested in thoughts ....

S

Some of the clutch diaphragm inserts that the thrust bearings push against are too soft (I don't know if this problem has been sorted out yet) I had one that ended up with a bad groove from the thrust bearing face (the rest of the bearing face was nearly touching) that was making some nasty noises, the 'fix' at the time was to fit and older hardened one from a second hand diaphragm, so I'd say it's hopefully either this / the bearing or both

I agree, release bearing or diaphragm insert, but if you want to put your mind at rest regarding crank thrusts, with the engine off, depress & release the clutch pedal, get a tyre lever or bar, place it between the bottom radiator bracket & the bottom crank pulley. lever against the pulley, if it doesn't move in, there is no problem there.

Sounds like there is a good chance I'm on the right track. The thing that worries me slightly is that clutch release bearings don't tend to break up. Maybe the clutch diaphragm is a more likely explanation.

Thanks

Simon

True to say that Mini clutch release bearings do not normally break up, in over 40 years with Minis, I've only encountered a few that made a light 'whirring' sound, but there were two that I replaced that sounded so bad I thought the crank had to be grinding it's way through the block, but not so, replacing the bearing was all that was needed. Sometimes you just get a bad bearing. I hope that's all you will need to do. Please let us know what you find when you take it apart.
Good luck, Rich.

Had one making some noise. One day there was screech and it seized up. It corrected itself so I could get home but I changed it straight away.

My experience with the modern bearings is that they do break down and make a horrible noise when they do. The older style with the flat thrust face seem much better than the newer ones with the narrow projecting rim.

Tim

Was the clutch set up when assembled,if not a grey diaphragm fitted to a lightened flywheel can put a tremendous load on the release bearing. The engine revs shouldn't drop when the clutch is actuated

Hi

It was set up when assembled and has worked up until now. There isn't a drop in revs when the clutch is engaged. I'm going to remove the endcover tomorrow and start to investigate, hopefully the cause will be obvious, I'm fairly sure it's outside of the engine in the clutch.

Thanks

Simon

It was the release bearing broken up. Fitted a new one and everything is fine!
Nice to have an easy problem to solve for a change.

Cheers

Simon

Relatively cheap fix, thank goodness.

Check out some of the posts and other information about
"Getting the clutch spring flat"...

For example, here...
http://www.minimania.com/Clutch_FAQ__non_Verto_

and here...
viewtopic.php?f=3&t=8141

Please note that "flat" relates to the diaphragm spring,
NOT the straps...

If you have a heavy clutch, like a grey, you end up stressing the
release bearing far more if the spring is not "flat".

If it's set up correctly, the assembly in its static position is all held
together with the maximum clamping capability of the spring applied
to the disk. ie, when you press the clutch, you are already at the
"top of the hill" so far as clamping is concerned. Any movement will
be under reduced clamping conditions, which is great, because you
are releasing the clutch...

If the spring was not installed "flat", when you press the clutch, you
are first pushing the spring pressure upwards before this goes over
the top. It is this that can lead to excessive wear and/or failure of
the release bearings.

If your clutch feels "springy", it's probably not set up correctly. If it
feels the same stiffness all the way down, it probably is...

I have had a couple of bearings where I have "pushed the middle out",
so I always have a spare bearing on the shelf...

Ian