Clutch plate differences coil or diaphragm

[Paudman]

Hi folks - can anyone clarify for me is there much, if any, difference between the coil spring clutch plate and the later diaphragm clutch plate?
I seem to have amassed a few spares in my time but they're all listed as diaphragm and I am wondering if there's any difference, as I want to replace a coil-spring clutch into the 1200 to use with an alloy bellhousing.
I have a full three piece set by Borg and Beck but it's diaphragm: HB1655RT
There is also a BNW clutch plate part number HB1655 which is close in part number to the B&B set above so probably diaphragm again.
I have Unipart GCP222 which MAY be Herald as that's what is written in pen on the box but appears to be Spitfire from on-line parts lists.
(The other one is GCP244 which I know to be Toledo, for a single-rail conversion in the Herald.)
Will any of the top three fit the coil spring clutch? They're all identical in size and appearance to the old plate that I removed, but I need to make sure there's no subtle difference that may cause problems. It's from a 1964 1200.
Thanks!

[Mark Hammond]

Hi Colin,

When you say is there much difference, what do you mean?  In terms of operation, in my experience, the coil spring clutch gives a softer pedal, but the diaphragm type is springier.  To change it, you'll need the matching flywheel.  As the later cover won't fit the earlier flywheel and vice-versa.

I had mine changed to diaphragm when restored as replacement coil spring clutches are thin on ground and the original clutch only lasted 27000 miles (or perhaps that was my Mother's driving).

Mark

[heraldcoupe]

Coil spring clutch plate is interchangeable with some A-series types, so readily available for Sprite, Midget and Minor.
GCP222 is 10-spline diaphragm for a Spitfire, it will be perfectly happy in a Herald but only with a diaphragm cover.
The application for the others are as you've listed.

You can swap to the full diaphragm setup by using the appropriate slave cylinder, flywheel and release bearing carrier.

Cheers,
Bill.

[Paudman]

Sorry guys, maybe I wasn't clear on the problem, my mistake. I have a NOS coil spring cover to use with a 1200 originally fitted with a coil spring clutch, so all the bits are there with the car. The only thing that isn't is the clutch plate, but I have the spare ones listed above. I'm confused as to whether those plates that I have can be used with all the other coil-spring parts, since many suppliers list a different plate number for either type of clutch. If I can use one of the plates that I have, I can reassemble the setup today; if not it'll have to be more parts by post...
Sorry for the confusion.

[Mark Hammond]

I believe that you need the correct coil spring type plate to match the cover.  I thought that diameter was also different.

Mark

[herald948]

Coil-spring clutch plates were described as 6 1/4", while diaphragm clutch plates were 6 1/2", if that makes any difference!

[Paudman]

It does! With such a small difference in diameter I thought there was actually no difference, but at 1/8 per side it's not surprising I missed it. New coil spring clutch plate needed then. Thanks!

[Pete Lewis]

a coil cover disc will also be about a 1mm thicker , if you use a thinner  diaphragm disc on a coil cover you will start off with a higher pedal load and a low clamp load., as it wears this will get worse until you loose clamp and have premature slip.  if that helps,
if you fit a coil disc to a diaphragm cover you get the reverse effect the pedal load reduces and the clamp load is excessive..  

Peter

[Paudman]

Thanks Pete; it's on the shopping list for Stafford. I might as well do it right first time and save trouble later.

[Mark Hammond]

There are coil clutches on eBay from time to time.  I'd just convert to the later type.  Triumph changed it for a good reason I guess.

M.

[Paudman]

Possibly cheaper to manufacture, not always a good thing....  ;D
If I were to do so, am I correct that the diaphragm clutch fork is a different fitting to my coil clutch fork, so am I right in that I'll also require a bellhousing? Which means I can't use my early alloy one...

My current one is this type: http://www.ebay.co.uk/itm/triumph-spitfire-clutch-fork-/261075013978?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3cc948915a#ht_500wt_1413

But the diaphragm sort appears to be this type:

http://www.ebay.co.uk/itm/triumph-herald-clutch-fork-/261075014619?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3cc94893db#ht_500wt_1413

Am I correct?? This is the only photo of a different type that I can find, and all mine in my garage are the alloy type.

[Mark Hammond]

You are correct.

M.

[Jezmond]

No, that's not correct. I've just gone through the process of returning to the original alloy bellhousing but with a diaphragm clutch. I had mistakenly used a horrible heavy cast iron bellhousing 20 years ago and wanted to go back to alloy. What you need is:

1. Flywheel from a diaphragm clutch car. So late 1200 or 13/60
2. The bearing carrier for a diaphragm clutch. Not the clutch release arm, just the carrier. They are very different in depth.
3. Full diaphragm clutch including release bearing. (Canley Classics are recommended)
4. Slave cylinder for a diaphragm clutch.

Bear in mind that you will almost certainly have to file out the slave cylinder so that it fits further into the bellhousing. 5mm is about right.

I have photos I can post if necessary.

[Mark Hammond]

No, what I meant was that the forks/carriers are different between coil spring and diaphragm clutches.  You can of course intermix bellhousings with the correct mix of carrier/fork/clutch etc.

M.

[Jezmond]

Ah yes, quite right Mark :-)

[heraldcoupe]

490 wrote:

But the diaphragm sort appears to be this type:

http://www.ebay.co.uk/itm/triumph-herald-clutch-fork-/261075014619?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3cc94893db#ht_500wt_1413

Am I correct?? This is the only photo of a different type that I can find, and all mine in my garage are the alloy type.

That's not suitable for any Herald I've encountered.
The clutch fork is the same on all Heralds from mid-1960 onwards, only the bearing carrier differs. The fork in the first listing is the correct type.
Until mid-1960, the all-alloy gearbox casing was in use, and that had a clutch fork with integral hinge. Not relevant to any herald with separate bellhousings, whether iron or alloy.

Didn't we go through exactly the same conversation on the Yahoo group last week?

Cheers,
Bill.

[Paudman]

heraldcoupe wrote:

Didn't we go through exactly the same conversation on the Yahoo group last week?

Cheers,
Bill.

That was the pivot pin thread, however I did raise the question of differing release arms in one of my posts to which you replied:

"The bearing carrier is different, the rest of the release arm assembly
is the same across all clutch types from about Q2 1960 onwards.
The all-alloy gearbox has a different release arm altogether though,
which may be what you're thinking of. That has an inbuilt hinge, which
is screwed in place inside the bellhousing, no pivot pin to drop out......"

Flywheel I have (13/60) and half a dozen later bellhousings so am bound to have a later release arm, full diaphragm clutch kit awaits but not keen on having to file the slave cylinder... I just want to fit and forget things...  ;D

[heraldcoupe]

490 wrote:

not keen on having to file the slave cylinder... I just want to fit and forget things...  ;D

I thought you were talking about NOS clutch components, rather than the modern approximations. Opening the slot in the slave cylinder is often needed to make the modern components operate correctly, whereas a clutch to the original (coil or diaphragm) should operate correctly when used as a matched set of parts,

Cheers,
Bill.