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MG MGB Technical - clutch issue

i aquired a 76 B last fall which has sat in dry storage for the past 10 years.the sub frame,inner rockers and floor were pretty much shot which i have replaceed.the engine was rebuilt before putting it to bed which had siezed which i have freed up and it runs fantastic.does not puff or rattle and oil pressure is great.my problem is that when i dep ressed the clutch the drivetrain engages.when i let the clutch up it would stop and i can shift gears.now its at the point where i can shift gears no matter what and the car will not move.this is new for me,any feedback would be great. DEZ
z dezsenyi

I would chack and see if the driveshaft is turning when you let the clutch out with it in gear.. It sound like a broken half shaft.
DARNOC31

if that was the case would it not grind putting into gear.i can put into gear with or without depressing the clutch pedal.
z dezsenyi

Hard to understand what your problem is due to your method of communication (mis-communication?). But, the clutch connects the engine to the transmission. If the transmission grinds when being engaged, it generally indicates a clutch that does not release properly. If, when the engine is running, the transmission can be shifted without grinding the gears, it generally indicates that the clutch is stuck in the released position and is never properly engaging the flywheel.

The reasons that a clutch would become fully disengaged would be either a hydraulic system problem or a broken pressure plate.

A broken pressure plate would require removing the engine and the gearbox for disassembly and inspection.

A bad hydraulic system would be recognized by the clutch fork being held backwards by the pushrod out of the slave cylinder bolted to the transmission.

I think this is what you were trying to ask?

Les
Les Bengtson

good morning Les,because of a couple heart attacks 3 years ago the brain factory has a hard time putting thoughts into words ,so here we go.when i first fired this car up after 10 years it would not go into gear.i shut the car off,slide it into gear and started the car back up.with the pedal to the floor it would move,and when i let the clutch up it would stop rolling.now it,s at the point where you can slide it in and out of gear with the pedal engaged and dissengaged.also as a side line this engine was out of the car 10 years ago for a rebuild. THANK YOU DEZ
z dezsenyi

You mean you had drive with the clutch pedal to the floor, but no drive when the pedal was released? In gear and engine running both times?

Could be friction plate reversed.

"now it,s at the point where you can slide it in and out of gear with the pedal engaged and dissengaged"

Are you now saying that with the engine running, you can put it in and out of gear with no grinding noises regardless of whether the clutch pedal is up or down?

Could be release arm jammed down for some reason holding the clutch fully disengaged. It *could* be a broken half-shaft, but I'd expect some noises, and it will be easy to check if the prop-shaft is turning (broken half-shaft) or not (no drive through the gearbox).

But given both these situations, unless you have changed something in the clutch system in the meantime, it seems to me there is some major malfunction with the clutch which needs the engine out to investigate.
PaulH Solihull

you nailed my discription perfectly paul.looks like when they put it together they screwed up.i will need to pull the engine and have a look. i was also wondering if it could have anything to do with the slave cylinder.
z dezsenyi

There are several problems you can get with the slave, one is caused by air in the hydraulics or the push-rod that operates the release arm being too short, such that it cannot disengage the friction plate far enough, causing grinding when trying to select reverse with the engine running. The second is that the push-rod is too long, and the piston is getting to the bottom of the cylinder but still not allowing the clutch to fully engage, causing clutch-slip or possibly not engaging at all. The first thing to check is that you should be able to push the push-rod and hence the piston back into the cylinder a little way at least. Releasing it again should allow the internal spring to push it back out again gradually.

The release arm or release bearing could also be incorrectly seated, or incorrect parts causing either of these problems. The clutch slave, or the master, could be the incorrect part giving the wrong ratio of pedal travel to slave piston travel. The second check is to measure the push-rod travel as the clutch pedal is fully operated and released, you should get about 1/2".

Depending on the results of those tests might help in deciding whether the engine has to come out or not. However any problems in those areas would normally result in consistent symptoms, until something breaks at any rate. Given the complete switch in symptoms I doubt it is simply a hydraulic or clutch slave issue.
PaulH Solihull

This thread was discussed between 07/04/2013 and 08/04/2013

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