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MG Midget and Sprite Technical - Type 9 Clutch Problem

Eventually got the frog back on the road complete with new clutch. Only trouble is when it gets hot it refuses to disengage the engine from the gearbox!!!
Specifications:
1330 A plus engine, Type 9 gearbox, frontline bellhousing, operating arm and roller bearing release with 1275 clutch master, slave and pushrod. New standard 6.5" clutch with a replacement frontline plate (the plate was in the car when I got it and I had it refurbished when I stripped the car as you cannot get them now).
The clutch worked fine before the rebuild even though the front bearing was floating around loose rather than fitted in the flywheel.
Went to a friends this Saturday and it was hot, got to his house and couldn't select reverse, lots of graunching noises. Went and had a cup of tea (of course)after which the whole thing cooled down and selection worked again with a tiny gaunch. When it was graunching, if put in gear before starting then started it would not pull until the clutch pedal was released. Before you ask, the holes in the operating arm aren't worn and there is no excess play anywhere.
Anybody got any ideas?? If not I'm going to have to bodge the push rod!!
Graham.
Graham P

Is the gearlever a quickshift?
Daniel Thirteen-Twelve

Graham
"The clutch worked fine before the rebuild even though the front bearing was floating around loose rather than fitted in the flywheel."
Are you refering to the spigot bushing.I had similar symptoms in my MGA with T9 box last year.The problem turned out to be the spigot bushing not seated correctly in the end of the crankshaft.The shoulder on the gearbox mainshaft was rubbing on the spigot bushing,everything was fine with cold engine but after running for awhile could not get reverse without turning off the engine.My solution was machine 40 thou off the face of the spigot bushing and make sure there was clearance there before reassembly.It works fine now.
Tony


Tony Cox

Daniel, the answer is yes it is a quickshift. However I can't see what difference that would make to the mechanical operation of the clutch. It is not that it is difficult to select, but that the primary shaft in the gearbox keeps spinning even when the clutch is operated and won't allow the non synchro reverse gear to mesh.

Tony, I think you might be onto something, I had to have a new bearing (spigot bush) turned from phosphor bronze and I'm wondering if it is a thou or so undersized internally, in which case high temperatures might cause it to expand slightly, grab the primary shaft and make it reluctant to disengage. Engine cools down, bush loosens it's grip, clutch works again!!!!
Looks like an engine out job some time in the future, but it'll have to wait till the weather is a lot worse as I'm not missing this fabulous driving weather.
thanks guys, Graham.
Graham P

I once had a problem selecting reverse gear when the engine and gearbox was hot which was entirely due to the quickshift. The problem didn't occur with the regular shift and the quickshift was sent away for modification and return to me.
Daniel Thirteen-Twelve

Try a replacement gearlever saddle bush (£8 plastic)

afteer the second fail on my clutch a deeper competition MGA clutch release bearing was fitted
Nigel Atkins

Graham, I think Tony and yourself are onto something with your suggestion. Sounds like the sort of thing it could be. That spigot bush for the conversion is a nightmare. I had 3 that were too loose and and in the end like you I got one made myself. Probably needs opening up slightly and then lubing when putting back together. Pity its such a big job to get to it. Been there!
John Payne

Yes John, I think Tony is right, it fits the symptons perfectly and I can't think of any other set of circumstances that would. So I'm hoping to keep it cool until I have the engine out.
Graham.
Graham P

This thread was discussed between 18/08/2012 and 21/08/2012

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