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MG Midget and Sprite Technical - Stalls when clutch depressed

Hi Guys, Its been a long time since I've been on here - I'm doing a SLOW rebuild midget so I'm driving the MGBGT. A friends MkIII Midget keeps stalling at idle when the clutch is depressed and he's asked for some help. I haven't looked at yet but I thought I'd get some ideas. Initial thoughts are it could be the release bearing or even the engine thrust bearings but I wondering if there could be some simpler reasons. Thanks, Chris
Chris Hale

Could be a clutch disk that has started to come apart and is slightly bent. Or, something that once happened to me, could be a pressure plate problem. Mine had a the part break that the levers pivoted on. Because of that they were not fully releasing the clutch.

Oh, many years ago I had a pilot bearing so tight that I could not shift from neutral when at a stop.

These things are only a possibility if it is happening when the transmission is in gear and it stalls. Then when it is in neutral and does not stall.
tomshobby

Thanks Tom, although I haven't been to check it out yet I think it stalls in neutral so I don't think it associated with the gear box. I'll have to check the gear changes to see if there is any associated clutch drag or noises indicating a problem in that area. Chris
Chris Hale

Have you measured the amount the crank pulley moves back and forth when you push in the clutch peddle?

Prop
Prop

Prop, not yet as I won't get to go round for a week. I must admit it was my first thought that it might be the crank thrust washers and will check end float as you suggest whilst my mate pushes the clutch. Just hoped I might have overlooked some simpler/cheaper reason! Chris
Chris Hale

driving a midget will certianly create an addiction to hope and wishing

Ill mainline some hope and and snort some wish for you for a simpler issue and remedy
Prop

collapsed/cracked/snaggy carbon release bush thing?
Rob Armstrong

Chris,
It sounds tome like it is the release bearing worn down so there is too much drag when the clutch is pressed. I would have thought that this would be accompanied with some noise though.
It could be too much end float on the crank as Prop says. It could also be that the idle is too low in the first place. The clutch depressed puts a little extra load on the engine and the revs always drop slightly. That may be just too much. Also make sure that there are no air leaks in the carb/inlet. A weak mixture will make the engine rev higher at tick over but it will not be a powerful and slightly more load with the clutch depressed may be enough to stall it.
D Brown

Hey D,

Now thats an intresting thought

I was exploring the idea of the revs being to low also but could only come up with He might have been wearing diffeart shoes and is not giving it enough gas....

cha chug, cha chug, cha chug, LOL.

Prop

Prop

Thanks Guys. Like I say I haven't had chance to look at it yet, but D, I think a slow idle and the extra load on depressing the clutch might be the culprit. He did say that he had adjusted the idle so might be that. He didn't mention any noise as failing release bearings tend to show up like that in my experience. Cheers, Chris
Chris Hale

idle needs to be around 800 to 1000...but im a beliver in 900 minume, as thats the point where the oil pump starts to become In effeciant
Prop

I know I'm chipping in a bit late here, but I had a release bearing worn away to nothing in my car, it was running on the metal housing for the bearing. It caused the revs to drop when the clutch was pressed yet made no noise, presumably due to the traditional A series lubrication in this area!
AndrewF

This thread was discussed between 21/10/2010 and 01/11/2010

MG Midget and Sprite Technical index

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