Diaphragm Clutch

[Jonseddon]

Hi I’m getting my 1275 A+ engine rebuilt. Currently it has a spring clutch which feels weak.

Looking at fitting a diaphragm clutch to mating to my rib case gearbox. Can I use a midget release bearing in my clutch fork to make it work or are there any other parts I should use.

Thanks in advance

[philthehill]

Are you using a ESM Minor modified flywheel with Marina/Ital crankshaft?
https://www.morrisminorspares.com/engin ... s-p1239064
The use of the release bearing depends upon the method of operating the diaphragm clutch cover operating fingers. Some diaphragm clutch covers have a bearing pad which presses against operating fingers and which will allow the use of a carbon thrust. If the diaphragm clutch cover does not have a bearing pad then the carbon thrust cannot be used - you have to use a roller release bearing. A roller release bearing is available from the likes of Peter May Engineering.
https://www.petermayengineering.com/pro ... aring-kit/
Make sure that the diaphragm clutch cover will fit inside the gearbox bell housing. You may have to grind a small amount of metal from the inside of the bell housing to allow the diaphragm clutch cover to fit without metal to metal contact.
Have a look at the link below:-
http://gerardsgarage.com/Garage/Tech/TO ... arings.htm

[Jonseddon]

Sorry Phil, the engine is away getting rebuilt so not clear on what flywheel is on it. Currently it has a spring clutch and the rebuilders have noted that the diaphragm clutch has a different depth.

I could just got back to a new spring clutch,just wasn’t impressed with the old one which was almost new a felt like it could easily slip. The rebuilt engine will have a torquier cam, wanted to make sure I didn’t just slip straight away.

[philthehill]

The Marina/Ital flywheel will not fit the Minor bellhousing so a non starter there.
You have to use a ESM Modified Minor flywheel on the Marina crankshaft or fit a 1275cc Midget crankshaft with a 1275cc Midget flywheel fitted with a 1275cc Midget diaphragm clutch. 1275cc Midget con rods have to be used with the 1275cc Midget crankshaft as the Marina/Ital and Midget rod journals are different sizes.
You have to use a ESM modified rear engine plate when fitting the Marina/Ital engine to a Minor gearbox. The Marina/Ital rear engine plate fitted to the Marina/Ital engine is not suitable for use with the Minor gearbox.

[Jonseddon]

Sorry Phil it was previously running in the Traveller, 1275 A+ mated to a rib case box, the clutch was a spring one. Trying to understand what needs to be done if I wanted to fit a diaphragm clutch.

[philthehill]

Thank you for the clarification.
You will need the type of release bearing in the Peter May link above.
The clutch cover in the link below is suitable so long as the mounting bolt holes in the flywheel are located the same though it is an easy task to index drill new mounting holes and clutch cover locating pegs in the flywheel. Your local engineering shop should be able to do that if required. If you already have a 7.5" dia clutch cover fitted you may be able to get away with not having to re-drill the mounting holes and fitting clutch cover locating pegs though this is dependent upon the make and style of diaphragm clutch
https://www.petermayengineering.com/pro ... ver-helix/
When I fitted the original diaphragm clutch to my MG 1275cc engine I had the 1275cc flywheel refaced and index drilled for the new 7.5" diaphragm clutch cover. I have done this several times so know the routine. The clutch current fitted to my minor is a 7.5" diaphragm unit mounted on a steel flywheel and is a Ford RS 2000 unit used with a roller release bearing.
With the information given in this post and those of mine above you should have no problem in upgrading to a diaphragm clutch.
Good luck.
Phil

[Jonseddon]

Thanks

[Jonseddon]

The existing clutch is wider in diameter than the new diaphragm clutch the engine builders tell me.

I have been told a midget release bearing should match up to the rib case box using the existing clutch fork.

Any ideas?

[philthehill]

I suspect that the existing coil spring clutch is 7.5" dia. The modified ESM flywheel is machined & indexed drilled for a 7.5" clutch. The 1275cc Midget diaphragm clutch is just over 6". As I said above the 1275cc 'A' Plus flywheel will not fit into the rib gearbox bell housing so the flywheel I am pretty sure will be a modified ESM item unless the 1275cc Midget crank, rods and flywheel have been fitted.
The use of the Midget release bearing will depend upon whether the clutch cover has a bearing pad or not.
You will note that the diaphragm clutch in the Peter May link does not have a bearing pad so a roller release bearing is a prerequisite.
As an aside -If you do use the Minor mechanical linkage you will find the clutch very heavy to operate so a well used mod is to lengthen the pedal lever on the intermediate relay shaft. Replace the chassis relay shaft bush with a poly bush otherwise the rubber bush will not last long.

[Jonseddon]

Thanks again Phil