Hi Ellis,
I am assuming that your SRM clutch is the type where the inner drum does not have a lip at the inner edge
and the shaft adaptor incorporates a thrust washer ??
If so then the first plate that goes into the basket is a friction, check that it sits flat against the inner face of the outer drum,
Photos are in the link I posted earlier
This is the modified design as used on late Triumps/A65s, the spring pressure is no longer concentrated against an unsupported plain plate at the back of the pack,
I use 10/40 castrol motorcycle oil in the primary, suitable for wet clutches, others prefer ATF ???
Car oils can contain anti friction additives that will cause clutch slip
HTH
John