MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - 78 B Clutch issue

I am looking at purchasing a 78 B. The car was last driven several years ago and according to the owner, it drove fine into the garage where it has set.
While inspecting the car today, I tried to push the car in gear and the car moved freely, but the engine did not turn. I tried all gears. The prop shaft is turning as I push. The clutch pedal feels a little soft, like the return spring might be missing. I have not crawled under the car to check the motion of the slave pin.
Any suggestions for what to look for?
Cleve Crews

I have heard of plenty of instances where the clutch has frozen engaged, but never when disengaged. I can't imagine what is happening, but someone will know! Did the owner store the car with the clutch pedal wedged down perhaps?
Mike Howlett

Ditto. If the clutch was stuck in the disengaged position, which I reckon is virtually impossible, a couple of pumps of the clutch pedal would end up feeling solid, not soft, as the master would be trying to pump fluid into the slave cylinder but it's piston won't be able to move any more. Unless, there is a return spring on the release arm, which would be non-standard.

Either there is something grossly wrong with the clutch or gearbox, or it simply isn't in gear when the prop-shaft is turning.
Paul Hunt

there can be many other problems with a car that hasn't been driven for several years and could involve a lot of recommissioning work to get it ready for use let alone reliable use - but that might be the type of work you're looking for
Nigel Atkins

Does it have overdrive?
Dave O'Neill 2

Dave,
That would be nice, but no it doesn't have OD.
I tried every gear and pushed it both frontwards and backwards with the prop shaft moving, but no engine movement.
I'm going back to look at it tomorrow.
Cleve Crews

Sounds to me that the clutch slave cyl is very stiff/almost seized and pushing the pedal down has disengaged the clutch which is not seized therefore the gearbox turns but no connection to eng.
Garth
J G Bagnall

Well, well, well...
So, I've never seen this before, but it's what it sounded like was going on to me. The slave piston was stuck out as if the clutch pedal was depressed and was not allowing the slave pin to retract. I knocked out the pivot pin and the release arm popped back in the relaxed position.
Looks like it needs the clutch slave/master/hose replaced. Good news!!!

Cleve Crews

I once had this on the move, driving through traffic in my local town. It threw me at the time, particularly as by the time the car had got home (on a trailer) it was working again.

Seized slave cylinder (to my shame it still had same fluid/not been bled over previous 26 years!). New cylinder and hose fixed prob - a bit of a pain to bleed, I recall. This was all a couple of weeks before a trip to Le Mans. On that journey a different clutch fault manifested itself: the carbon in the release bearing totally disintegrated. Maybe connected with earlier fault. Managed to get it home with much graunching!
P A Allen

Possibly the piston getting cocked in the bore, I have heard of that happening once, although based on mine I'd have said there simply wasn't enough room for that to happen.

As far as bleeding goes many report difficulties. I've always reverse bled mine, in fact reverse filled which does the bleeding at the same time, by linking the left caliper and slave nipples (they are the same size) and using the brake pedal slowly and carefully, shutting the caliper nipple on each up-stroke and opening it for each down-stroke.

However recently someone wrote how he bled his simply by filling the master and pumping the pedal about 40 or 50 times, until it felt right, and it seems to have worked.
Paul Hunt

I purchased an MGA from a motel parking lot for the great sum of $75.00. THe owner said the transmission was gone again and he was not paying any more as his son was always breaking it. I towed the car home and in less than 15 minutes was driving it with all being OK. The slave cylinder piston had cupped and locked outside the cylinder.I popped the piston back in and bled the system.
Eventually I had to replace the rod as the hole to the clutch lever was well worn along with the corresponding hole in the lever.
P.S. This was way back in 1968.Wish I still had it.
Sandy
ss sanders

This thread was discussed between 31/07/2014 and 02/08/2014

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now