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MG Midget and Sprite Technical - 1275 clutch problems

My car (Healey IOW Frogeye) slips into gear nicely when cold but in heavy traffic with lots of gear changes the pedal travel gets less and less, the clutch doesn't disengage properly,and crunching begins. This gets progressively worse until it won't change at all, and staying in second (don't have first - worn layshaft) isn't an option as it creeps then stalls when the brakes need to be applied.
This started on the Bridges of London run, which was a bit awkward to say the least! I've bled it three times since then, but no visible air bubbles. However, once bled, there is plenty of pedal travel again - until next time.
There is no loss of fluid and I have those heavy duty steel wrapped pipes, so I doubt expansion is an issue.
One suggestion has been a master cyclinder seal on the way out - could this be an answer if there is no visible fluid loss?
Any ideas greatly appreciated.
C Whiting

Just noticed the previous thread which is along rather similar lines - but might be a different problem altogether of course.
C Whiting

Very different problem mate.

Your problems are either a slave cylinder seal fault pull back the rubber boot on the slave and see if fluid runs out

or

The master cylinder seal is faulty again remove the covers of the master cylinder and check for fluid leaks

If this diagnosis is correct then you should be able to get a better clutch by pumping the pedal a couple of times before operation
Robert (Bob) Midget Turbo

Thanks for that - there is no fluid leak in the master boot and the reservoir is still up to the upper mark - I will however take a look at the slave boot though next time I get some daylight. Pumping I have tried - but it makes no difference once there is insufficient travel in the pedal. But the clutch operation does instantly improve when bled again.
If the seal in either cylinder was poor, wouldn't there be fluid loss? Or air in the system?
C Whiting

Not necessarily sometimes a bad seal will allow air to enter the system.
Robert (Bob) Midget Turbo

...but there isn't any air in the system - at least no bubbles when I bleed it. Can fluid absorb air and become less functional despite showing no bubbles? I'm using a one-man system with a one-way valve and watching as the expelled fluid exits into a jar filled with clutch fluid to above the level of the tube end - might I be missing something? The fluid is new. But there's definately something wrong somewhere...
C Whiting

CW,
Unless, when bleeding, your push the slave piston back up the bore of the slave cylinder and secure it there, it is possible for air to remain trapped within the "dead" area of the slave and not be dispelled from the system. Only problem is this wouldn't then explain why your clutch appears to work for a while before deteriorating again.

Guy
Guy Oneandahalf Sprites

As for the bleeding part - If you can force yourself into the space beneath the steering wheel or take the seat out this is the simplest and in my opion the best way - the problem is the bleed nipple restricts the fluid and air being cleared quickly enough.

This always works for me (and our Australian friends !):-

http://www.spriteparts.com.au/tech/bleeding.html



richard boobier

Richard
Save your poor back. Fit a remote bleed and do it all standing beside the master cylinder.
Alan.
A Anstead

Someone had already fitted a remote to my car - which is an absolute godsend. I can stand there pumping the pedal with one foot while watching the fluid exit into the jar (while smoking a cheroot and sipping a glass of wine at the same time if I so fancied).
But seriously, I hadn't realised the importance of wedging or wiring the slave piston.
There is definately no leakage from the master, so I thought about buying a repair kit for the slave - until I found you can get a new unit for 25 from Sussex Classics on eBay. On the grounds that there might be damage to the old slave interior anyway, I forked out for a new one rather than mess about with a kit which might not work.
The fact that it works fine immediately after a bleed indicates, I think, that the old one has had it.
Thanks for all the advice.
C Whiting

It is a good starting point mate.
The only issue is that it seems to be a long way out of the cylinder but who knows.
Best of luck
Bob Turbo Midget England

When the new slave arrives. Cut the top mounting hole into a slot facing outward. Screw the top bolt into the bellhousing to an approximation of the thickness of the hole lug on the slave. Slide the slave up onto the bolt and insert ther bottom bolt as per norm. The top bolt is a b****r to get in (on a standard Frogeye) and this method eases the pain
Alan
A Anstead

I think that the problem is the release bearing, not the hydraulics or slave cylinder at all. I suspect that this could fit all your symptoms:

1. The bearing has worn / part disintegrated so that is effectively thinner and when the clutch is operated, the lever and therefore the pushrod has to move further rearward to disengage the clutch.(as in photos)
2. Coupled with this the slave piston is reaching the end of its travel and coming up against the end circlip before the clutch is fully disengaged, giving the "solid stop" feel to it.
3. The partially disintegrated thrust is no longer running smoothly on the clutch cover fingers so that in use it gets "kicked back" as the clutch rotates. Whilst it is re-aligned initially when you bleed the clutch, this then quickly deteriorates when you begin to drive the car.

You could possibly check this last theory by repeatedly pressing and releasing the clutch with the engine off. Then start it and see if it is temporarily improved. It may not be the bleeding, so much as merely pumping the clutch with the engine off that is temporarily improving it.

Whilst you may need a new slave cylinder, I doubt that it will solve your problems. You could just be wasting money on that.

If it is the thrust bearing, then 13,000 is a low mileage for it to disintegrate, but there was a thread on here a little while back about a batch of badly manufactured ones that fail early. Secondly, a good new one will likely get damaged if the pushrod is too long so that it remains permanently in contact with the clutch - effectively "riding the clutch" all the time. The carbon ones are not designed to do that!
Guy Oneandahalf Sprites

Bit confused - mileage isn't 13,000 (it's 22,500) and I haven't posted any pictures (as in "seems a long way out of the cylinder") - might this thread have become confused with the one about the 1500 midget with clutch problems?
I have new slave and am going at the top lug hammer and tongs with a junior hacksaw as recommended by Alan.
C Whiting

Sorry mate you are right I am confused with the other thread. Hope my senior moment has not caused you pain.
Robert (Bob) Midget Turbo

Me too, my apologies! I got completely muddled about which thread I was responding to! My detailed reply relates entirely to M J Chapman's problems with his 1966, 1098cc car.

Sorry!
Guy
Guy Oneandahalf Sprites

Not a problem at all - I'm still stunned by the amount of helpful advice offered on the site. Have just opened up the upper lug of the new slave cylinder with hacksaw and file as advised by Alan and am greatly looking forward to my day off tommorow, when I can lie in a huge muddy puddle under the car and remove all the skin from left and right knuckles in near darkness. With a song in my heart and an eye full of clutch fluid.
C Whiting

Does anyone know where I get hold of the bloke who worked at Abingdon in 1958 and designed the clutch slave cylinder mounting to the bellhousing? I'd love to share a few thoughts with him, once I've had the skin grafts to my knuckles sorted at East Grinstead.
However, I would like to buy a beer for whichever of the former owners of my car had the good sense to modify not one but both lugs of the body with a hacksaw. The bottom one came off easy as blinking anyway, but I don't think there's any way the top one could ever be fully unscrewed with the tubular frame member in the way. I still had to saw my best (ok, only) 9/16in AF spanner in half to manage the two turns in half an hour it took to shift the thing.
But after two hours cursing and swearing and a frantic sprint into the kitchen to wash clutch fluid drops out of my left eye using eldest daughter's shot glass, I now have a fully-functioning clutch.
I was a bit worried by the metallic tinging coming from the clutch when I moved the lever by hand when old slave was disconnected, but now it's all back together it seems to work fine.
Thanks to everyone for the advice - much appreciated.

C Whiting

A most useful description of how to do that awkward job. Had you considered writing am alternative maintenance manual. Many would find it a very helpful guide of what to expect.
Guy Oneandahalf Sprites

LOL it was designed like that well before it was fitted to Abingdon cars and well before 1958.
Robert (Bob) Midget Turbo

There already is a humerous handbook on slave cylinder removal - the Haynes MG Midget and AH Sprite workshop manual. Chapter 5, section 3, Slave cylinder removal and refitting.
"Undo and remove the two bolts securing the slave cylinder to the clutch housing."
Absolutely hilarious.
I would be no good writing an alternative manual though. My knowledge is still in its infancy and everything technical and useful was mentioned by other members on this thread - for which many thanks. Took it up to London (with the roof down this time) yesterday and clutch was fine, if a little noisy.
C Whiting

This thread was discussed between 09/01/2011 and 16/01/2011

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