Regarding the line-up of the lever and hole, I agree that this is ballpark
at best. My final setting is always based on getting the ball above the
seat sufficiently to get the pressure to the pistons in a "reasonable" time.
On a related note, I just learned recently of the reason for decreasing the
diameter of the accumulator piston on the later A-types. The original
larger accumulator piston results in a greater volume of oil being
"accumulated" under pressure. When the unit is engaged, the pressure falls
off as the oil rushes to the operating pistons, but it only falls slightly
because of the volume in the system. By going to a smaller piston and less
volume, the pressure drops off more and it takes the pump slightly longer to
build up the oil pressure which results in a smoother shift. In other
words, the later units will not "slam in" as hard as the older units seem to
sometimes. Made sense to me.
Mike
The point about setting the operating valve is a good one; but incorrect
setting will normally just cause the unit to shift slowly or not work at
all, rather than slip in overdrive. Best practice, IMO, is to ignore the
"setting lever" and measure the ball movement directly. Opinions vary on
how much the ball should move (See Nelson's article for a study of behavior
at various lifts), but I use .030 - .040" based on an old article by Del
Border (which was actually for a big Healey, and said 1/32" - 1/16"). The
TR4 OD I have in my TR3 gives almost exactly 1/32" lift with the setting
lever lined up, and does have some wear in the linkage, so I feel this gives
credence to the numbers that Del quoted.
Randall
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