Originally Posted by
JohnW
Dick; I guess you ARE indeed correct...the shoes are the SAME LENGTH and the associated parts ARE located straight across the centerline. How they are "handed" is because of the way they are cast. There is an offset cast into the shoes to properly space them away from the backing plate. That is, the WIDER SIDE of each shoe ass'y being closest to the backing plate. Incorrectly installed, the brake cylinder bars will not match up to the tangs on the shoes correctly and the shoes will scrub on the drum (They sometimes do anyway!). If I had correctly mentioned that I was referring to "left and right" while assuming "straight up" (12:00 position on each side) as the reference, I would have been "acceptably clear" (I think!). Mea culpa. This explains naming them "Rt and Lt" as to which way the casting is "offline" when viewed from the "outside". [Hmmm. I wonder if I am going to reget saying that???]
So, When the brakes are installed on the gearleg so that the inlet fitting for each brake line is in the extreme-most "aft" position...on the RIGHT SIDE Brake, the "R" shoe is DOWN (or RIGHT OF -CLOCKWISE TO- the pivot); on the LEFT SIDE Brake, the "L" shoe is DOWN.
On a correctly installed setup with original Piper shoes, BOTH the shoes have the part numbers readable from the "wheel and tire" side of the brake (got a complete setup right here in my fat hand). If later Piper castings and/or aftermarket replacement part shoes are different, then I am unaware of that!
If you are assembling the shoes to the backplates on the bench, view with the pivot at 12:00 and the "R" shoe goes on the left, and the "L" shoe on the right...for both brakes. Then when they are installed on the gearleg in the original Piper positions (straight AFT of the axle), the shoes are correct as described two paragraphs up.
So sorry for the confusion. Strictly MY fault! BTW, all these brakes work perfectly well no matter HOW the units are "timed" to the axle. Piper used "straight back" as the brake line inlet position to best protect the "plumbing" from ground damage by hiding everything behind the relatively "massive" axle structure, but you can occasionally find them installed in different positions (sometimes to clean up a non-standard wheelpant installation, sometimes because they were just installed wrong, and anything -logical or not- in between).
Mike; Don't overlook that the "leak downstream of the parking brake" may actually be IN the parking brake itself. There were two different makes of P. Brake valves originally, and they use different O-rings internally (fortunately, you only waste a couple bucks if you buy both kinds!). In a LOT of cases, you also can spot a cracked flare somewhere under a B-nut. Why these so many times do not leak enough to readily spot where the problem is, is beyond me. Also, its not uncommon to find that you MAY have old, old rubber brake lines up inside the belly to allow the brake lines to flex at the gear attach points, that "balloon" when you mash on the brakes. That will cause similar "creep away" issues. Them puppies are about 70 bux per side.
MANY PEOPLE do their runups "on the move", steering with feet, braking with one hand and "checking" with the other.