Replace spring type clutch with diaphragm type on S1...any experience?

I need to replace my removed spring type clutch and would like to fit a diaphragm type. Does anyone have personal experience of doing this (and can share) or do all S1 owners stick to the original spring type when replacing?
I have no experience of driving with the spring type clutch. Is not noticeably heavy?

Also, my flywheel is a little scored (not much) Is it possible to have it skimmed or is it not worth the bother (thinking about balancing and clutch plate tolerances)

A spring pressure plate is noticeably heavier on the foot, than a diaphragm: it’s not a huge deal, but the flywheel has to be redrilled and -doweled for a diaphragm clutch.

Get that flywheel faced, too.

I’m trying to figure out why you have a spring clutch. Is this a 66? I’ve always understood the 10" spring clutch to be a 3.8 thing.

IME the spring clutch is quite noticeably stiffer than the diaphragm. The diaphragms I’ve driven felt downright modern whereas my spring clutch is a major workout. Of course there are other variables like whether the pedal return spring is in one piece or broken, and how tight the slave spring is adjusted.

Judging from the photo of your flywheel it appears to me to already have two sets of drillings, for both type clutches and inner course and an outer? Whether it’s an original that has been modified or is a replacement type I couldn’t guess. I know places have been selling dual purpose flywheels for a while.

The one and only benefit I know of with the spring clutch is that it is stronger. It won’t slip under load until the friction plate is basically gone, so it’s good for high performance racing engines. I’m doubting a 2+2 falls under that category.

Good catch! I think the OP is set.

The major difference is with the spring clutch, the further down the pedal goes, the more force you have to apply. Holding the pedal down takes significant effort. With the diaphragm clutch, for part of the travel, the force increases, the further down the pedal goes, then it starts getting lighter. It takes considerably LESS force on the pedal to hold the pedal all the way down. Max effort for an E-Type spring clutch is typically on the order of 2X that for a diaphragm clutch.

OTOH, we put a new diaphragm clutch in a friends S2 back in January, and his pedal effort is actually HIGHER than that on the spring clutch in my 3.8! Go figure! I have to wonder if he was sold a “high-performance” clutch, as I’ve never felt a S2 with such a heavy pedal.

Ray L.

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The removed clutch has 17 Apr 1970 painted on it. I assume it was possibly old stock fitted in 1970?
Thats good news if it is drilled for the Diaphragm type.

OP? what is that?
Does it also need dowels?

You should have locating dowels. I assume the diaphragm should as well.

Original Poster… you!

Dowels are easy: any good industrial supply will have them, or you can likely reuse the ones already there.

I guessed so…just wanted to be sure !

i presume they are interference fit. How do you remove and fit them?

Grab them with a good set of vise grips, then twist them out.

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On most flywheels, you will find the holes are in are drilled all the way through. Much easier to tap them out from the back and not damage them with vise grips.


Good point, if through holes exist: IME, for clutch cover dowels, they are often blind holes, for good reason.

Done properly, the Vise Grips leave little to no damage.

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There is a serviceable 10" spring pressure plate on Ebay now if you’d like to stay original.

I have thought about it Mitchell, but if I can, I want a diaphragm for ease of use. I have no experience of a spring PP, but don’t want a heavy clutch (with todays traffic jams) I really could do with trying one on a test drive as it may be an unreasonable fear.

I have thought about it Mitchell, but if I can, I want a diaphragm for ease of use. I have no experience of a spring PP, but don’t want a heavy clutch (with todays traffic jams) I really could do with trying one on a test drive as it may be an unreasonable fear.

I truly don’t know why you would use a spring clutch. Their use seems to have been largely abandoned in favor of the diaphragm clutch, for the good reasons set out here. I also think that the use of locating dowels has been largely abandoned as well.

In the early 80’s I had both an Stype and a MK2, one had a diaphragm the other a spring. I couldn’t tell the difference. However in those days the spring rate was different depending on the model. Today I believe the suppliers only make one clutch and that is designed to take the full torque of the 4.2 E type. The spring version has purple springs, hence some owners fund it hard work.
For what it’s worth my Mk9 has the purple springs, it was fitted about 20,000 miles ago and is in perfect condition, hence it’s going back in when I finish my engine rebuild. I found it ok, but the Mk9 has a different actuating mechanism to the Etype which I think make life easier.

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The coil spring clutch is not original for all S1s. All 3.8 and some early 4.2a. If you swap, which you should, remember to switch release bearing as well as they are different.

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