I don't use one- so my clutch is now self-adjusting, like 99.9% of more modern cars, including Rover Mini.

Any ideas on why they designed it to have a spring on the slave if it doesn't need it? Most small cars back then had adjustments on the clutch. 1st one that didn't I think was the Hillman Imp. When Rover fitted the Verto clutch to the Mini in 1980? they did away with this adjustment. Note their slave cylinder is almost the same, except for mounting.

Any premature throw out bearing wear? Not so far, the only load on the bearing is the ounce or two now provided by the tiny spring inside the slave cylinder.

Do you still run a 20thou gap on the arm? No, you wind the adjusting screw in so it's well away from the arm. Standard clutches that run no gap here DO overload the release bearing (and the engine's thrust washers).

I might try it without as well - I have never liked the original setup

If anyone gets stuck and for some reason needs a new clutch return spring, a mop bucket spring works perfectly found this out at a service station today.

It is a ball bearing, I am running the current design RHP one, not the early (better) flat one which is pretty well NLA now.

lucky enough to have 3 of the flat one still in my possession not counting the ones on the cars

It is a ball bearing, I am running the current design RHP one, not the early (better) flat one which is pretty well NLA now.