CPS for mini

[Tom Parker]

Michael D. Porter <mdporter at rt66.com> wrote:

>Tom Parker wrote:
>> The standard Mini flywheel/clutch (its all one unit) is made of cast iron,
>> is about 10" diameter and weighs around 20lb. It's inside an alluminium
>> housing, and there is a fairly strong bulkhead between the driver and the
>> engine.

>I missed the first message, so, didn't realize you were referring to a
>Mini--a bit different problem... one which is minimized a great deal
>with a diaphragm clutch. The problem, as you say, is with clutch fingers
>coming off--and then all other hell breaking loose.

Ok, I've never seen the insides of the clutch/flywheel of any car except a
mini. I can't see how a clutch could explode without the flywheel being in on
the action. Are there clutch designs where the flywheel is not used as a face
for the friction material?

As I understand it, the weakness of the mini clutch is the pressure plate. The
pressure plate is like a big donut, and has "legs" at right angles to the
plane of the friction material. The pressure plate sits behind the flywheel,
with the legs going through holes in the flywheel and the friction material
sandwiched between. A huge spring pulls the pressure plate towards the
flywheel to clamp the friction material. There is a picture of it fully
assembled and on the engine on my web page, in the mini section, titled "A
useful modification to the SP puller"

It is the legs at right angles on the pressure plate that make it weak. These
legs set up big forces inside the pressure plate as they try and twist under
centrpetal forces.

>Here's another
>possibility, which is much lighter--make one from Kevlar cloth. Easy to
>mold around the clutch housing, and not too expensive if you can find a
>source to buy it by the yard, then fold it up and sew it into a bag. Add
>some eyelets through the bag and the Kevlar so you can tie it onto the
>clutch housing.

Very interesting. It would be strongest if you made it into a complete
loop around the bellhousing, so you wouldn't have to tie it down so much.
Or maybe you would... Hmm... If the flywheel does go, it is likely to slice
the alloy bellhousing in half leaving a kevlar loop with high speed iron and
alluminium fragments inside it... Then it wouldn't matter if it enclosed the
bellhousing as there wouldn't be any bellhousing left :-/

--
Tom Parker - tparker at nznet.gen.nz
           - http://www.geocities.com/MotorCity/Track/8381/