Vibration.

[cuk]

Hi, 1972 traveller.

Have a bit of a problem at the moment!
When the clutch pedal is pushed all the way down, on tick over, I get this terrible low vibration through the car, also the tick over drops and ignition light is nearly on. (as if putting extra strain on the engine)
Let the clutch up and all fine tick over spot on - engine speed perfect.

Wondered if anyone has come across this same problem?
Any comment's greatly appreciated.

Paul.

[philthehill]

Sounds normal to me.

The engine will reduce in revs when the clutch pedal is depressed.

The idling speed/revs should be adjusted so that when the clutch is depressed the ignition warning light starts to come on and glimmer.

[Myrtles Man]

Sounds normal to me.

The engine will reduce in revs when the clutch pedal is depressed.

Pardon my ignorance Phil but why should that be? My own expectation would have been for the revs to rise as the slight load of the gearbox was removed. Clearly not the case but I can't really fathom it.

[cuk]

Sounds normal to me.

The engine will reduce in revs when the clutch pedal is depressed.

The idling speed/revs should be adjusted so that when the clutch is depressed the ignition warning light starts to come on and glimmer.

Thanks phil.
Have already done this. I cant increase tick over any more as I start to get a bit of pre ignition when turned off, All timing correct.

[philthehill]

Myrtles Man
When the clutch pedal is depressed the carbon thrust presses on the clutch pressure plate which loads the engine causing the engine revs to reduce.

cuk

You should not be experiencing pre-ignition or running on of the engine when the ignition is switched off. Pre-ignition is usually caused by a hot spot inside the combustion chamber.

When was the engine last de-coked?

[Myrtles Man]

Thanks for the clarification Phil; you lives 'n' learns. So, it now appears that I've been barking up the wrong tree for, essentially, all my motoring life insofar as I've always depressed the clutch when starting an engine, especially from cold and in the winter, on the basis that doing so removes the extra burden of the possibly gloopy oil in the gearbox, enabling the starter motor to spin the engine that bit more vigorously. That's a misconception then, presumably.

[cuk]

Myrtles Man
When the clutch pedal is depressed the carbon thrust presses on the clutch pressure plate which loads the engine causing the engine revs to reduce.

cuk

You should not be experiencing pre-ignition or running on of the engine when the ignition is switched off. Pre-ignition is usually caused by a hot spot inside the combustion chamber.

When was the engine last de-coked?

Yes understand about hotspot, but don't think that's my problem now. When I drive to work, I get caught in traffic jam for about 30-40 minutes (bumper to bumper) so engine temp must rise, so cant take up tick over to high. its fine now, but to rise it anymore, would be too fast.
Also everything is new. Engine, radiator, carburettor, distributor, (not gearbox) All done about 2,000 miles. Its just this clutch vibration problem.

[philthehill]

myrtles Man
If you have a roller/ball bearing release clutch thrust pad (unlike the Minor which in standard form is a carbon thrust) the rotational/resistance/loading on the rear of the crankshaft and thrust bearings is greatly reduced when the clutch pedal is depressed. Then you will then get some benefit of disengaging the gearbox internals from the engine on cold mornings.

I had originally a carbon thrust operating a heavy duty clutch and that did load the rear of the crankshaft and thrust bearings causing the engine revs to reduce when the clutch pedal was depressed..
Now I have a ball bearing release with the full comp clutch assy and it is much better though the end of the crankshaft and thrust bearings are still loaded but the rotational resistance is considerably less.

[Myrtles Man]

OK thanks, that makes sense. I'll continue with my clutch-down starting ritual then (except on the Minor of course).

[ManyMinors]

Also everything is new. Engine, radiator, carburettor, distributor, (not gearbox) All done about 2,000 miles. Its just this clutch vibration problem.

If you had so many new parts recently you probably had a new clutch fitted too? Many members have reported problems with recent replacement clutches. Have you tried some adjustment to the clutch mechanism to see if that improves it at all? There really shouldn't be a "terrible vibration" as you describe and my best guess is that you have a faulty clutch.

[geoberni]

OK thanks, that makes sense. I'll continue with my clutch-down starting ritual then (except on the Minor of course).

I've always depressed the clutch because of the 'lighten the load' theory, but also in case it was left in gear; back in the day it wasn't always clear where the gearstick was when driving a different car.

On my 'modern' I must depress the clutch because it's a push button start.

[cuk]

Also everything is new. Engine, radiator, carburettor, distributor, (not gearbox) All done about 2,000 miles. Its just this clutch vibration problem.

If you had so many new parts recently you probably had a new clutch fitted too? Many members have reported problems with recent replacement clutches. Have you tried some adjustment to the clutch mechanism to see if that improves it at all? There really shouldn't be a "terrible vibration" as you describe and my best guess is that you have a faulty clutch.

Thanks for your reply. Yes I did have a new clutch assembly + clutch + bearing, although not sure were the garage got this from. (gearbox was fine).
I will try what you said and see if they're is any difference.
Cheers.

[ManyMinors]

If you had a new clutch fitted only 2000 miles ago by a garage, I'd be taking it back to them

[paul 300358]

Can you fit a DTI to the front pulley and then measure the play in the crank thrust bearings by pressing the clutch and seeing how much the crank moves forward?

[cuk]

If you had a new clutch fitted only 2000 miles ago by a garage, I'd be taking it back to them

Thanks will let you know.

[cuk]

Can you fit a DTI to the front pulley and then measure the play in the crank thrust bearings by pressing the clutch and seeing how much the crank moves forward?

Thanks for reply. But I don't have one of those, also that's a bit out of my league!
But I will let everyone know, when I locate the problem.