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MG Midget and Sprite Technical - Clutch 1098-1275 issue.

Took my midget to the Motor museum today furthest it’s travelled in 30 yrs after a prolonged state of hibernation and being in bits . I am having a trouble with the speed the clutch re engages between gear shifts. I lift my foot up and the clutch take a second to re engage causing over revving as I go back on the throttle . A couple of guys today suggested a fluid return issue . It is a 66 car with its original gearbox and 1275 engine and clutch with the 3/4 dual master cylinder. It looks like I put an earlier slave on it for the 7/8 set up for drum cars . Could this be the issue? The clutch is very heavy. If I was to replace the slave I would put a remote bleed and slot the top bolt hole too this time . Any ideas welcome , thanks .



Mike Fairclough

Looks like you have a flexible pipe there, it may have partially collapsed inside causing slow fluid return. I used a 7/8" MC for a number of years with no issue and disc brakes on the front and only changed to the later 3/4" MC when a replacement was required.
David Billington

I'm with David on this. I had the hose for the rear brakes collapse once and the slow return symptoms were the same. Replaced the hose and the problem went away.
Martin

Mike

Is everything the same with the hydraulics as the last time it ran, or have you replaced any pipes or hoses?
Dave O'Neill 2

I believe the earlier slave did not use the flexible pipe. Yours looks like the later slave with the larger bore unless you used an adapter? I agree with the others that the pipe needs to be checked first.
With the larger bore slave and 3/4 master the clutch is not at all heavy. There is also less risk of the clutch overthrowing
The 1275 slave is the same as fitted to a MGB V8.
Bob Beaumont

Thanks for all the input , the collapsed pipe is a possibility. Dave I honestly can’t remember. The car has only been shunted round not actually driven on the road for years. I think I replaced the slave since it has been laid up . Bob the flexi pipe goes down from the MC towards the slave then has a female cone nut on the the flexi is then attached to that . It’s free not on a lug on the chassis leg like the older cars . I’m thinking if I go for the pipe might as well do the cylinder whilst I am at it . If I do go do that route do you suggest the later 1275 cylinder? Will I have to change pushrods too ?
Mike Fairclough

mike, So yours has no metal pipe running from the M/C to the clutch slave? Just a flexible pipe? Was your car originally a 1098cc car with a dual clutch/brake master cylinder?
Bob Beaumont

Sorry Bob didn’t explain that very well . No it’s a copper pipe coming from the dual cylinder down to the lower chassis leg where it joins a short flexi to the cylinder . Yes the car is a 66 with dual cylinder, disc brakes and originally had a 1098 the engine was swapped over long before I had it . I have definitely replaced the slave and flexi pipe probably about 20 yrs ago and sadly car has moved much until now . Maybe I put the wrong one on when I replaced it but I seem to remember I replaced like for like .
Mike Fairclough

Sounds like a flexi hose issue from here--just renew the hose and see what happens
William Revit

Thanks Mike

Yes the flexy pipe is the first check. If you are thinking of changing the slave then the later GSY113 slave from the 1275 Spridget gives a nicer clutch feel. Its 1" bore rather than the 7/8".
I use this on my Frog which has a 1275 engine and 3/4" bore M/C.
Its quite possible the original 7/8" bore slave was retained when the engine was changed and you replaced like for like. It works ok with the 1275 clutch just gives a harder pedal.
Bob Beaumont

I agree with Bob - I have exactly the same set up. I don't have a flexy pipe but the copper pipe is coiled to allow for movement. I had it custom made by Automec to accommodate the different connector to the 1275 slave.
Bill Bretherton

That’s great Bob and Bill I will go down the new flexi and later slave and hope that solves it . Just hope it’s not the MC !
Mike Fairclough

Something else to check is that the clutch pedal can move freely. Pull the clevis pin and make sure the pedal isn’t sticking.
Dave O'Neill 2

I was one of those "couple of guys at Gaydon" - I'm glad everyone agrees with my initial diagnosis!

Nice to meet you and chat Mike. Hope you get it fixed soon.

Cheers,
Malc.
Malcolm

Thanks David , I have checked the pedal and bolt through all seems freely moving . Yes Malc it was me who picked your brains thank you and a few others too , it is a great thing that we can tap into others knowledge like this .
Mike Fairclough

Well I got the old slave off and cut the flexible pipe through and the bore inside was tiny and very soft so this is probably the culprit. As I have now got a 1275 cylinder to go but I hadn’t realised the fittings for the pipe are so different. Bill I see you had a pipe made up . Did anyone else have any other suggestions ? Brake / clutch pipe threads and sizes are a mystery to me .
Mike Fairclough

Mike, there's a screw in adaptor that screws into the slave and matches the standard pipe to that slave. Sorry, I used one but now have no idea of part numbers or supplier though.
GuyW

By coincidence, bleeding the front brakes on my Capri today, to cure slight uneven braking, when braking gently. Hard braking is even.

Nearside easy. Without needing to press the pedal, open the bleed nipple and fluid flows freely.

Offside, open the bleed nipple, nothing. Open a bit more nothing. Take out the bleed nipple, nothing. It takes a press on the pedal to get fluid to emerge.

Took off flexi, can't blow through it. Collapsed. New one ordered, 10 quid.
anamnesis

Mike,

I got my adapter from Powertrack. https://www.powertrackbrakes.co.uk/

Bob
Bob Beaumont

Thanks for all the input. Things have escalated ( like they do ) and I now have the whole pedal box out on the bench in bits , it was a bit of mess. I will probably see if I can get a copper pipe made up to go direct from the M/ C with a correct fitting to go straight into the slave.
Mike Fairclough

If you are 'going all the way' in copper, remember to get them to add the double loop coil to allow for movement and vibration between body tub and gearbox and prevent future cracking.
GuyW

This thread was discussed between 21/05/2023 and 25/05/2023

MG Midget and Sprite Technical index

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