Even though I have a Garretson proportioning valve that keeps the
pedal feel pretty good, there's always a bunch of free play before
the brakes start really working.

Anyway, I had an excuse to get into the rear wheels, and I adjusted
all the adjusters like 1/32 of a turn back from where they grab the
wheels. The pedal free play was much much less and all was right
with the world. Of course about 3 days later we did the autocross,
and by the time I was driving home the excessive free play was back.
.

If this wasn't a street car in a stickler inspection state, and a sort-of
'classic' car that I want to keep close to normal, I'd go to a real rear
caliper design.

if you went to the real rear caliper design, what would you do about an emergency brake?

The actual adjustment is 0.008"............. 1/32" equates to 0.03125. Hmmmmmmmm

I'm sure it's also related to the cubit
But seriously you would have to know the
threads per inch and tolerance of the screw
and use pi in there somewhere.

The important part is that the 0.008 which
is factory spec would be crappy even if it turns
out to be accurate. The front brakes are
spec'ed for 0.002 (as I'm sure most other
regular disc brakes are). I have never heard
anyone claim that you must set to 0.008 or bad
things will happen. So my method is get as
close to dragging as possible.

I just wish it would last.

I set 0.004" and they stay great for a period of time. I didn't look, but you're running a /6 - the pistons are a few mm larger and put more pressure on the pads. Maybe they just wear faster.

Long ago, and far, far away, the instructor at P-car school said to ignore the 0.008" figure and use 0.004" (measured at the thickest point of the rotor). It works, and resolves most of the low pedal issues I've ever encountered. I can't recall any time when the adjustment got loose enough to recognize as a problem, but then I don't work on many track cars, and the couple I've done in the past didn't have stock brakes. Going to a system where you lose the handbrake is shaky, at best, and illegal in most (if not all) states. The Cap'n