I eventually managed to get a used clutch for my 43 M20 project. A you can imagine most of it was horrible, but good enough to work out how it should have been. (I hope)
After some hunting it seems that only Indian quality parts are readily available. Even if so called UK made they should be ashamed of themselves.
I have tracked down Surflex friction plates and have ordered some.
It seems that even though Surflex have part numbers for the steel plates, know one carries them.
If this is indeed the case, I'll approach them and see how many the minimum order is. (A lot I expect)
Mark
email (option): pes.sales@btconnect.com
Fibre plates should be .093" thick....Watch out for pattern items that are too thick. The steel plates are all .048" thick (18 gauge) with a 'tang' clearance of .030" in the relevant slots...
Interestingly the material for the two plate types was different...A3-2 for the driving plate and A1-3 for the driven plates...
I've looked that up but have not determined to date how that equates to a modern spec...
I've used Saftek (in Yorkshire) in the past to make batches of the fibre plates in the correct thickness...I also got them made in a material that would run 'wet', removing the need for the 'top hat' cover and gasket...Ian
email (option): ian@wright52.plus.com
Thanks Ian,
The Surflex ones are supposed to be 2.5mm, so just a little over.
As for sheet steel it's become a living hell to get what you want. 16g invariably ends up be 1.4mm Which is nearer 17g
Ask for it in a specific temper, and they don't know what your on about.
Cold rolled sheet much about 3mm is next to non existent.
To ask for a particular chemical composition would be a waste of time.
It might change if you purchased a tonne at a time, but we only make little things.
email (option): pes.sales@btconnect.com
The internal tangs of the steel plates don't wear much, most of the wear occurs on the external tangs and the clutch basket..The clutch has plenty of friction area due to the one piece fibre plates and the unusually high number of plates overall...
I did work out that by reducing the overall number of plates and increasing the thickness of the plates that wear to improve the amount of load bearing surface on the edges, the overall plate stack could be kept pretty much to the standard height...
I didn't actually try that out but it would be an experiment worth doing.. A one off set of the required plates could be readily produced by a laser cutting company at a reasonable price...Or you could fit a Triumph clutch instead!!...Ian
email (option): ian@wright52.plus.com
It's funny how many people think laser cutting is the answer to many profiling jobs in thin sheet material. And for welded assemblies, in many cases it can be.
As for many sheet type engine components it's horrific. The cut edge often acts as a saw! The other problem I came across, was how poor the accuracy is. If you Ian, or I was operating the machine I expect in many cases it would be good. But often the operator is under orders to cut as fast as possible. I've had stuff up to 1mm off due to thermal shift on the plate.
Water jet cutting is much better in many ways, but the price isn't so good.
The best tool I've found for low numbers is the CNC mill. Draw the profile in CAD and ask the CAM software to output a file to the mill.
I'll play around and see how well I can make the original design work before I tamper.
We have an A65 clutch which is yet to be released that could be adapted as a universal clutch of other projects if I live long enough.
email (option): pes.sales@btconnect.com
I have sets of Ian’s wet plates I believe Ron has as well and they cure the oil problems on dry plates ,running wet means less wear on every thing well worth the effort to track them down
email (option): warbikes@gmail.com
Over the 30 years have been running the M20 I have probably tried every variation you can think of.
The one I found best was welding the drive plates in pairs and running one set short with old worn fiber plates .
Now I do a lot of engine breaking so that might contribute to the extreme corrigations in the drum but the double plates dresses nice & square seemed to last the longest & work best.
Remembering I oxy weld so the welded face tend to be quite soft.
What gets fitted at any particular point of time depends upon what I have in hand or can get either quickly or cheaply ( both better still )
The B series 6 spring could be made to run very sweetly but regularly required adjustments
The next on I hope to fit will be an A10 4 spring if I can get the gear box internals together & working before the clutch is toast
If we ever get the mill happening then I will mill out the battered slots of the drums with sprockets that look a bit less like a WobbyGong shark then braise in some key stock for the tangs to run against .
An old speedway racer did that to my A 10 six spring and that took all of my youthful neglect with flying colours.
I did try to do it myself but my skills with a file leave a bit to be desired and to work the edges of the slots need to be dead square.
I showed this to a club member who worked at one of the universities in the fabrication section and he milled a slot in a couple of lemgths of key steel and braised these into the filed out slots on his A10 outfit and that worked really well for him.
However he got retrenched , the bike went into the mortage & he left the club.
Or perhaps even resprocket some of the toothless ones .