Morris Minor Owners Club

IslipMinor wrote: The 1275 A-Series flywheel is the same basic size as the 948/1098 engines and the gearbox bellhousing is also the same size, irrespective of engine.

Never actually measured them I do have a 1275cc Midget one that I can measure has someone got a 1098 Moggie one they can measure.

But with different size clutches the mounting holes must be in different diameter circles and on the couple of cars I have driven with the 6 1/2" clutch on the midget engine it was quite sharp when compared to a Moggie flywheel with a 7 1/4" clutch and Mike has hit on a point the Midget 1275cc clutch is diaphragm against the standard coil spring clutch unless you alter the relay shaft as Mike mentions.

The diameter of the flywheels for 948/1098 and Spridget 1275 are all the same - but yes the wear faces and the fixing holes for the pressure plates are different. AND - 1275 engines have 6 bolt fixing to the crank, 948/1098 are 4 bolt. The Marina/Ital flywheels are larger diameter overall - thus the backplate and gearbox bellhousing are larger to suit - and the starter is mounted further out from the crank centreline.

Without this modification the clutch will be very sharp and heavy and you will not enjoy driving in traffic.

I can only repeat what I said before, 1275 diaphragm clutch, completely standard Minor linkage, nice progressive action with no problems in traffic at all - the Lord Mayor's Show parade was as good a test as any of whether a clutch works well in traffic!

As a general rule, for the same driving torque capacity, diaphragm clutches are lighter to operate than one with coil springs. That's one of the reasons they have completely replaced coil spring units and I can't see that the 1275 one is an exception?

You have got me thinking now Richard I wonder if you have hit the nail on the head.
Is the heavy clutch action caused by using the Moggie coil spring clutch instead of the Midget Diaphragm clutch when using the Midget flywheel.

I can only go from personal experience. I fitted the 1275 Midget engine complete with diaphram clutch and unmodified linkage and found it to be heavy and extremely sharp. I modified the linkage as detailed which resulted in a perfect pedal movement and weight. A friend with a Midget engine with an unmodified clutch says that his is also heavy.
If the diaphram clutch was no heavier then why go to the trouble of installing a hydraulic clutch?

And why did they not arrange the hydraulic 'leverage' to be such that the clutch action was smooth and light ? Sounds like your extended linkage is the easy and sensible way to go on this !

Like I said, it works for me. The one inch extension was pure guesswork, too much and it would have had too much pedal movement resulting in the clutch not disengaging at the bottom end or slipping at the top end.
For a lighter clutch the extension could possibly go to 11/4 in max.
I kept a spare relay shaft in case it all went wrong.
Ref. Kevin's last comments, the Midget and Minor clutches are different diameters so a Minor coil spring clutch will not fit a Midget flywheel which is why I fitted the diaphram clutch in the first place.