Well Kiddies, I finally have the final on my Spec clutch "project".
I've had the thing working well enough for my 1400 lb HAMBster, but still not up to their claims for it. My latest disassembly (mostly to take up some slop in my "floater" conversion) proved the most revealing. Once again I took'er down to individual parts, and noticed, now that there's enough wear to produce a pattern, that the pressure plate's face is worn more on one side than the other. Curiosity being one of my albatroses, I looked into why.
Further critical inspection noted that the contact ring/point with the diaphragm was irregular. Well, something like that certainly might produce the wear pattern I saw. Onto the granite table it went, and out came the gauges.
Didn't take long to verify that the diaphragm contact point was short vertically by .094" on the side over the unworn part of the face. Spec (or their jobber?) had milled the damn back at a slight angle to the face, rather than parallel.
I have no idea whether this is an anomoly, or a production problem (and thus the cause of other folks' Spec problems as well), but I decided (my damn Hoosier bone headedness) to rectify it myself. I see no sense in taking something back to where it was done wrong in the first place.
About an hour spent on the granite, with a large flat file and height gauge, and the back was properly parallel with the face.
So back into the car it went, and lo & behold, it's easily twice the clutch it was just yesterday. Gee ...... what a shock.
Anyway, I thought I'd pass along the info. A pressure plate only pressing on one side doesn't make for much of a clutch, Spec's or anyone's.