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MG Midget and Sprite Technical - Clutch Slip

hello All
I have just took the old girl out for its first unoffical spin And the clutch seems to be slipping

It is a marina engine and it is fine in 1st gear but when given some stick in 2nd the revs increase with only a small amount of acceleration. The push rod from the slave cylinder has already been cut down But I am wondering if I should cut it down a bit more as first gear is ok

Thanks Ian
I Pickering

With the clutch not pressed there should be a small amount of free play in the clutch operating arm.
Jeremy Cogman

ok will look at this
Thanks
I Pickering

Jeremy
How much is a small amount of play? is 1mm sufficient or should it be more ?

Thanks Ian
I Pickering

did it slip before ...what did you do, that this is the "1st spin/drive" was it a restro....or a repair.


what engine do you have and the carb set-up?


the reason I ask, is if its NOT sliping in 1st gear but doing it in 2nd, 3rd, and 4th....Im wondering if you got a popit valve malfuntioning/burnt or a butterfly vavle mis-aligned


if the clutch was spining, it would spin the most obvious in 1st gear, as it has to pull the car from a stop.....

prop
Prop

No Prop, what he describes sounds like clutch slippage.
Trevor-Jessie

Prop,
Trevor is right. The part you are missing is that the higher the gear, the MORE it resists accelerating. First gear has the best mechanical advantage (longest lever). In normal wear, you will first notice clutch slippage in high gear.
David "too many slipping clutches" Lieb
David Lieb

Depends where you measure it but as long as the arm can be moved a little then it's not pressing against the clutch and 'pre-releasing' it (my term).
Jeremy Cogman

Thanks David, I couldn't think of a good way to explain it. I just wanted Prop to be able to focus his creative energies elsewhere. ;)
Trevor-Jessie

Prop
It was the first go after 20 years off the road, it is definetly clutch slip but I am unsure of the set up for the marina engine Like I said the push rod has already been shortened I hope it just needs another lump off it

Thanks Ian
I Pickering

Ian, I am confused. This should not be a guessing matter of just lopping lumps off the slave cylinder push rod. Plus why would a marina engine make any difference. If the pushrod was too long in the slave cylinder then you would not have been able to bolt up the slave cylinder to the gearbox without a struggle. You would have had to depress the pressure plate by pushing the slave cylinder to get the bolts to line up.

That said you ought to be able to feel the slave cylinder as being loose when the pedal is not depressed. I have a slight suspicion that the clutch fluid is returning to the master cylinder and pressure is building up in the system and holding the slave pushrod onto the clutch actuating arm and making it slip. I think you should do a simple check first and try pushing the rod back into the slave cylinder. If you can not push it back into the cylinder then open the bleed nipple and try again, if it goes back in it will force fluid out of the nipple and will prove the master cylinder has not cleared the vent hole.
Bob (Robert) Midget Turbo

Bob,
I believe you intended to say " I have a slight suspicion that the clutch fluid is NOT returning to the master cylinder..."
I would agree. I would say that the afore-mentioned 1mm of travel is nowhere near adequate. Perhaps using the wrong rod at the master cylinder?
David "that master/slave thing's ok, but not that way round -- Les Barker" Lieb
David Lieb

Ok just had a look underneath there is a small amount of movement on the push rod so that should be ok but there is some oily crappy stuff on the flange of the bell housing at the bottom.

New master + cylinder already fitted
I Pickering

Have you replaced the flex line? You may have debris that is preventing a "clean" return.
Trevor-Jessie

Ian sorry to be a bore but it was not a case of new master cylinder or not. It is a case of the pushrod of the master cylinder perhaps not clearing the vent hole in the master cylinder. Did you try to push the slave pushrod back into the slave cylinder? and did you do the same with the bleed nipple slackened off?
With a midget there is always oily stuf on the bottom of the flange, although contamination of the clutch is a distinct possibility
Bob (Robert) Midget Turbo

Thanks Bob I will Give this a Try over the weekend should i disconnect the push rod from the clutch linkage before I do this test

Thanks Ian
I Pickering

would it be possible to get the other half to operate the clutch while I watch the slave cylinder operate to see of it stroking correctly ??
I Pickering

thanks for the correction...and sorry for the poor advice....I have only delt with worn out clutch on several occasions....it seemed they always slipped to a degree in all gears.... your explanation is good info to know


agian thanks
prop
Prop

I can push the slave cylinder push rod back in and it does return but there is a strange clicking noise that happens when it is returning

I think my next option is engine and box out unless anyone can suggest otherwise

Thanks Ian
I Pickering

Check to make sure the tops of your pedal, where it attaches to the pushrod is in good condition? remove clevis pin and inspect hole in the top of the pedal and the end of the pushrod where it attaches, If the are severly oblong?? I did a clutch in a '79 Midget and it was slipping after I finished, could not figure it out, took off the rusted on pedal box cover and found the top of the clutch pedal completely trashed, it was hanging on by a thread.
Worth checking
Mike
MK Mike

This thread was discussed between 17/09/2008 and 18/09/2008

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