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MG Midget and Sprite Technical - stuck clutch

Afternoon, chaps.

I've popped a thread on here before about a clutch that won't disengage but i thought i'd ask for a last bit of advice prior to undertaking the unthinkable task of removing the engine and making sure the clutch hasn't been installed back-to-front.

Tactics employed so far include:

Being towed by another vehicle with my foot on the clutch
Starting the car in first, build up a (very) small amount of speed then jam on the brakes with my foot on the clutch
Starting the car in gear with my foot firmly on the brakes and clutch

I’ve been told about another technique of jacking the back end up and then dropping the car off the axle stands but that sounds frankly terrifying.

Any other pearls of wisdom? Brand new master and slave cylinders have been installed together with a new line so it’s unlikely they have let me down although it wouldn’t be the first time a new part has failed...

Cheers,

Jamie
Jamie Watt

Hi Jamie

If none of those techniques worked I would question is your clutch release mechanism working ie the hydraulics?

How confident are you that the hydraulics are working correctly?
Bob Turbo Midget England

Bob, im 90% certain but i guess i won't know unless i get another new slave cylinder and see if it works...
Jamie Watt

apart from the dropping the car off the axle stands - from what I've heard from others you can afford to be quite brutal with the other techniques

I'm sure Bob's with me that 90% certain about hydraulics isn't enough if you've been quite brutal in your previous efforts
Nigel Atkins

If im being honest, i've been a bit of a pansy with previous efforts. Its a newly built engine having run for less than an hour so im loathed to treat it roughly, im a bit of a girl like that! I think a new slave cylinder is probably a good investment if it potentially saves the engine coming out. At the very least it will tick a box and eliminate a potential cause.
Jamie Watt

Hi Jamie,
I know we have been through these things before, but since you are starting out again on your quest for the eternal truth.....

I would start by watching closely to see what the slave pushrod actually does when someone else presses the pedal. I only suggest that someone else does the pedal pressing task as it is fairly difficult - though not absolutely impossible - to do both things on your own!
So get under there, get comfy. take a torch, tape measure, emergency whistle and some sandwiches.

What you are looking for is how much movement of the pushrod occurs with a single press of the pedal. It should be about 5/8" (10 - 12mm) Anything less and you have a hydraulics problem.

The second thing to look for is that the slave cylinder piston moves its full distance without coming up against the end circlip of the cylinder. Its 5/8" journey needs to take place fairly well up inside the cylinder. If the movement is close to the end of the cylinder then it may be stopped by the end circlip before it has sufficiently compressed the clutch cover diaphragm spring.

And then last of all, whilst you are still under there gazing at the legs of your attractive assistant (or at the slave cylinder, which is what you should be looking at)....Check that the clutch fork isn't fouling on the bell housing case when it is moved.
Guy

how the master cylinder too ???

system might just need bleeding again

the stuff I've heard about is from a racer and the race engine was probably freshly rebuilt

You have to check with others (cos I don't really know) but I think up to a certain limit your engine and g/box will take the abuse

At least you don't need to worry too much about about damaging your clutch as you have little to lose

ETA: Guy posted as I was typing so my comments are out of order
Nigel Atkins

The reason I didn't mention the master is because if one focusses on what the slave is actually doing - and it is doing what it should, then one can simply rule out a whole bunch of potentially troublesome things "upstream" These would include master and slave cylinder faults, clutch pedal pivot wear, m/c pushrod and other bleeding problems.
Guy

Mine "stuck" after the winter, the gentle way I released mine was to get the engine right up to temp by running for over half an hour,then turning engine off, wedging the clutch down with a wood prop, then going to bed.
Next morning, a free clutch!!

Colin
C Martin

Sorry Guy I was just ladling on the doom

Collin’s is as he says a nice gentle method
Nigel Atkins

Don't apologise Nigel. Nothing like a bit of doom-mongering. But I do like Colin's gentle method.
'cept you don't get to lie under the car and contemplate life, the universe and things.
Guy

Jamie is this a 1275 a series midget?
If it is then an easy way to assume the hydraulics are fine is to get under the car and feel the clutch arm (this is the arm that enters the gearbox and is pushed by the rod in the slave cylinder.
If this is loose then get someone to press the clutch pedal, the arm should immediately become stiff as it will be trapped between the clutch and the slave rod. If this occurs it is a pretty good bet the hydraulics are fine. However if this remains loose for most of the pedal travel then this needs sorting before any other thing.
Robert (Bob) Midget Turbo

I only like laying under the car for shade

But your with the right person for doom, that why I like to keep my vehicles undersides black, I'm your 'the glass is half empty because it got a crack in the bottom and is a very dirty glass any way' type of person - and it appears to be a self fulfilling prophecy - Jack Dee stole my act and is not as natural as me at it


If there were more 'View vehicle profile' put up then it would speed things up

It's very easy to do, must be I've managed

Nigel Atkins

In the past I had a stuck clutch on a Mini. Tried all the usual methods. It took starting in gear and a 7 mile drive in 2nd (very early on a Sunday) to get it to free up. I had in fact just given up and turned round to head home when it broke loose.
G Hawkins

Its a 1500 midget, i've updated my profile to explain the nuances of the midget but always room for more detail!

There is definitely some push in the cylinder although how forceful that push is, its impossible to tell with the slave cylinder in place.

I have a niggling thought in the back of my mind that i'll share with you. With the slave off and the push rod sticking through the bell housing, i am able to push the rod freely forward by about an inch (more detailed measurements will take place shortly) before the release bearing makes contact with the plate with a very definite 'clunk'. Is this normal? My concern being that the slave might be working perfectly but it never pushes the release arm far enough to disengage the clutch.

This is driving me mad!!
Jamie Watt

Jamie,
That slackness in the slave pushrod and lever arm can occur when the clutch fork pivot pin has dropped out. But I think you already checked that didn't you?
Guy

Jamie I can't really help with your clutch but I did mean to make your car's profile available for others to see and thanks for taking that idea but your car's profile doesn't show

it's easy to get it to show here's how (best to cut and paste the info to elsewhere whilst you actually do it)

On your Welcome page - top l/h/s box - click on My cars

click on Edit (your car)

on that page click on drop down box to show 'Yes' after 'Allow others to see data'

then press ‘Upload’ button - youve done it

go back to BBS and it will appear (with your next post I think)
Nigel Atkins

Thanks Nigel, my profile page says that it should be available for others to see but for some reason it doesn't show, not sure whats going on.

Guy - i've checked the pivot pin and it seems to be in place. Should there be any slack at all like the slack i've got or should there only be a small amount of movement in the push rod before the release arm (and release bearing) make contact with the plate?
Jamie Watt

bl**dy computers

mind you if you'd followed my instructions below (or made the same mistake it wouldn't)

I misread Upload as Update

sorry to be off-topic but for others instructions should be;

On your Welcome page, - top l/h/s box – click on My cars

click on Edit (your car)

on that page click on the drop down box to show ‘Yes’ after ‘Allow others to see data’

press ‘Upload’ button if you want to add photo

then press ‘Submit Details’, you’ve done it

go back to BBS and it will appear with your next post
Nigel Atkins

Jamie,
Its a while since I had a 1500, but I think that in normal operation there would only be a small amount of fore-and-aft slack in the pushrod / clutch fork. But that would be with the slave cylinder in position. Presumably if you remove the slave there is nothing to stop the pushrod / clutch fork from pulling back away from the clutch.

Do check that pivot though. I seem to remember that there is a sleeve in the bellhouse casting that could be confused with being the actual pivot pin. The latter is supposed to go inside the sleeve. I do know that in my case the pin dropped put and I had very much the symptoms that you describe. I replaced it in situ by dropping an old coach bolt down through the pivot bushes, and that lasted well for years.

Sorry if I am flogging a dead horse on this idea!
Guy

Guy, i will definitely re-check the pivot pin, i'll re-check absolutely anything if it saves me from lifting out the engine! Just had a look on Moss, replacement slaves are £45, might try absolutely everything before committing to such a spend!
Jamie Watt

This thread was discussed between 28/03/2011 and 30/03/2011

MG Midget and Sprite Technical index

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