I'd just like to extend thanks to ...
... for their insights into rectifying my R40 clutch problem(s).
It seems I had 3 contributing factors.
1) The inside of the clutch bell had become glazed with all the slip I had generated in trying to get it set up over the last 4 weeks. A swift scouring with some 340 Wet 'n' dry cured that problem.
2) The flywheel pins were protruding some .3mm above the level of the shoe, meaning that when I measured the clutch gap, I wasnt measuring the full distance the shoe had to travel to engage. I tapped the pins through the flywheel by .5mm so that the tops sit slighly below the shoe, to allow for shoe wear. Now when measuring the gap, the bell can contact the shoe rather than perching on top of the pins, giving an accurate measurement.
3) The 2 speed had a burr on it such that while it appeared free at rest, when torque was applied, (i.e. the engine engaged), the transmission was getting stuck in second gear.
Reassembling the 2-speed with more attention to detail and de-burring cured that.
I picked up an RD logics 62604 pipe for the car off Ebay for £15ukp, and fitted that at the same time. It is a good match with the HPI RXS engine.
I tested it at the local track on Sunday, and all the clutch problems seem cured now.
The car is ballistic, and nailed. I'm looking forward to racing it, although I fear it may now be "too fast for owner"
Thanks again for all your help.
I'm still interested in...
1) Why the internal diameter of the inner thrust bearing race is 4.2mm and the outer race is 4mm: and why it is important that the bearing is fitted with that orientation.
2) Why HPI show shims on the inside of the thrust bearing, (towards the engine), where serpent, and all other centax style clutches show shims fitted on the outside of the thrust bearing. I've now fitted my shims on the outside of the thrust bearing with no apparent detrimental effect.
Did HPI make a mistake in the instructions?