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MG Midget and Sprite Technical - MG Midget Clutch Vibration

Any one got any experience of vibrations from the transmission which stops if you dip the clutch briefly. It appears to be intermittent. Currently have removed prop shaft and UJ’s appear ok. Wondering if it is associated with the release bearing? It doesn’t rumble.

Any thoughts gratefully received.


1972 MG midget.
David Lewis

Hello David,
other much more knowledgeable people will be along - what happens if you hold the clutch pedal down?

My (quick) thoughts would be clutch, have you checked the hydraulics, flexi-hose needs replacing perhaps, problem on slave cylinder (or master), release fork bent, releasing bearing worn, foot pedal not fully operating.

Clutch worn.

I need to rest after all that, for me, brain effort.

Nigel Atkins

I'd just add to nigels list

Ghost of a dead dog living in the clutch

I think nigels covered this one pretty well

1 Paper

Here is a really Really long shot... maybe some wear in the engines thrust bearings

Have someone one depress the clutch peddle back and forth while your watching engine front pulpy to move back and forth
1 Paper

Bad clutch disk
Stan Kowznofski

David
It all depends on when it vibrates
Does it do it on the road
Can you get it to do it stationary in neutral
Is it under load or cruising etc.
When you say it's coming from the transmission I guess you mean the gearbox area or ??? or is it the gearlever vibrating
William Revit

With what happens if you hold the clutch pedal down I was thinking when the car is stationary.

Also do you start the car with the clutch pedal pressed down?
Nigel Atkins

ETA: Gear lever tizzing is a good thought from Willy - and the other questions, I was giving a quick answer and to encourage others but it was given on not enough information to fully answer.
Nigel Atkins

There are four small damper springs arranged radially around the splined centre of the clutch driven plate. Has one or more broken, or is the centre of the plate starting to break up and pull away from the rest of the plate?

Bernie.
b higginson

Thanks all for the feedback. My first enquiry so didn't check for a couple of days!!!
To cover some of the many suggestions. There is no noise from the release bearing in neutral when clutch depressed. The vibration is only noticeable when cruising in top gear. Enough to make the bonnet rattle until I installed some rubber support blocks. Dipping the clutch gets rid of the vibration. It doesn't reappear until going back down through gears then back upto cruising speed. There may be slight noise and or vibration as speed is built up but unless your Midget gearboxes are significantly quieter and refined than mine you will understand the uncertainty!!!
I will have a close look at the front of the engine and pulley as suggested.
The gear stick does not vibrate as I recall.
Cannot road test at the moment as have all brakes stripped for service ready for the fantastic weather that is just round the corner. Started the work when we were snowed in!!!
Beginning to think may have to have a peer at the clutch.
Again thanks all for your replies.
David
David Lewis

Dipping the clutch drops the revs, and coming down the gears raises them, so it's revs related. You might try dipping the clutch and raising the revs to see if the vibration stays away. Sounds almost as if the harmonic balancer is about to let go, or you've lost a fan blade. I would have thought something broken in the clutch assembly would be heard or felt on take up - not necessarily at cruising speed. You might look for a broken engine / gearbox mount or a broken exhaust mount - something that would give rise to a harmonic vibration more related to engine speed.
f pollock

Have you checked the rear axle?
Nigel Atkins

I'm with F.

I'd have a good look at the exhaust pipe for any shaking going on... can the pipe be moved up or down side to side by grabbing it cold, and giving it a good rattle

Check and make sure your alt belt is tight and not flopping
1 Paper

Does it do it revving it up in neutral
William Revit

When its running again you could try removing the fan belt and re-testing. This will isolate water pump and alternator, take some lateral load off the harmonic damper pully and also cut down on other noises - which can help. But only for a short test for diagnosis purposes as the water pump won't be assisting.

I also wonder if it may be a slight misfire if it is mainly happening at constant low revs but slight driving load in top gear. Check the plug condition and the carb damper oil level.
GuyW

David,
there's a whole world of possibilities, they may help to be resolved or resolved with the car together and road testing and/or a thorough servicing check.

Following the theme of slight misfire it could include any of our old friends like electronic ignition, rotor arm, CB points, (condenser, coil)or HT leads, dissy cap, or perhaps fuel side or even the fuel - mostly all stuff checked in a service.

I'm afraid 1972 Midget doesn't tell us a lot, is it factory standard, updated/uprated, souped up to high heaven(?).

If you want to, you don’t have to obviously, you can add your ‘vehicle profile’ with details and set the link to be viewable which can sometimes help with enquiries – having put that I notice mine is the only one on this thread but if you look at other threads you’ll see I’m not alone in doing this.

Keep reporting back as your findings can help others now and in the future.

Nigel Atkins

Thanks all. I will work through your suggestions and report back.
'I may be some time' as the saying goes!!
David
David Lewis

Has it had any new parts fitted recently? Engine mounts, for example.
Dave O'Neill 2

This thread was discussed between 04/03/2018 and 08/03/2018

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