Hi catrat,
Sorry to hear about your failure so soon after rebuild. Several things come to mind :- (1) miss alignment (A) caused by crud between the engine/trans mounting faces.
(
worn flywheel/clutch shaft spigot (pilot) bearings, ditto front trans. bearing supporting the rear of the clutch shaft.
(C) wear steps on the clutch shaft splines and inside the clutch hub missmatched after reassembly-- splines not timed back to their original worn positions-- causing the hub to sit on the shaft eccentrically and/or not parallel to the center line of the clutch shaft, this inturn causes the outer teeth tips to gyrate in and catch on the wear steps in the f/wheel drive splines and stress the disc teeth.
(D) wear steps in the flywheel clutch drive ring teeth causing abnormal twisting loads on the disc teeth also, because no two discs will be exactly the same dimensions of the old unit--especially will fit (pirate) ones-- the tips of the teeth on one side of the disc can fully engage in the wear step and the other side can be on the unworn section of the tooth causing the disc to gyrate about in the f/wheel teeth thereby over loading and fractuing those teeth which are over loaded, ie, not all teeth carry the load evenly. Next time you engage the clutch another set of teeth get overloaded and so on until failure occurs.
(2) Inferior material used in after market (will fit) part.
(3) excessively worn engine main bearings.
Attached is a scan of a SMag. article Nov. 08 1948 for a D2 replacement ring, I assume the R2 is the same clutch here and the ring will suit. If the ring is not available through Cat you can request a drawing of it and have one made if that is part of your problem, or else dress up your teeth until you are satisfied the disc teeth have clearance to work on good even surfaces without stress.
Some of these things are a bit of a long bow but I felt we needed to cover everything I could think of up to now, hopefully others may be able to share their experiences of similar failures or thoughts.
Hope this helps,
Cheers,
Eddie B.