Drum Brakes 101?

[RoadWarrior222]

Hi folks,

Getting my brain fried by messing with the drum brakes on my Ford Escort, but asking general questions about drum brakes here...

So what was on the car was two shoes of equal length and layout each side. What I got in the box new both had equal length linings on, but had two differing positions on the plate. One has about 1/2" gap on the top, the other is positioned lower with about a 3/4" gap on the top. These are some sort of leading/trailing or dual servo design, however, the ones ahead of the piston, the primary or leading pads wore out more in the last set. Conventional wisdom is that the shorter shoe goes in the primary position on dual servo. Neither is shorter, but the one lining is lower on the plate, so I put that one in the primary/leading position. There is no help in any of the manuals I have, chilton, haynes or Ford FSM, all the pics in those make it look like the shoes are exactly equal.. The linings themselves have exactly the same number printed on the side of them.. so they're the same stuff.

Thing is, I'm getting slight ticking or vibration on application, so I'm wondering if it's the shoes jumping or not. New drums are on... I'm going to swap them side to side to see if I got a bad one and the ticking moves, but wanted to be sure I have the shoes in the right way round... if there is a right way... checked with a bazillion sources and from what I am finding and having to read between the lines, and memory of brake jobs past, the lower mounted one should be in front.. checked everything for the eleventy fifth time and it all looks right... but still ticks...

thanks for any clues or confirmation,

RW222

[inplansight]

Are the hubs in good condtion ? Run out?

Paul B

[turbovanman²]

Did you machine the new drums? If you got elcheapo beer can made units, they are seldom true.

[RoadWarrior222]

Are the hubs in good condtion ? Run out?

Can't feel anything in the bearing, seems very smooth, no play.

Did you machine the new drums? If you got elcheapo beer can made units, they are seldom true.

Well, inexpensive, "We don't get them coming back." but they might now.

Gonna flip sides later.

[RoadWarrior222]

So yup, the problem moved with the drum, then I mounted it backwards and rigged the depth gauge on a digital caliper to a stand, and it was warped somewhere around 10-15 thou. I think the tapping was the pads lifting and slapping on the backing plate. So, took it back and got another one... put it in... first, light, application tap tap tap AAAAARGH... but then I pressed hard and it went away. What I think happened there was that the surface finish on the drums is like small grooves, and the shoes wore to the groove on the bad drum, very slightly wore, and because that was off, the shoes got grooves that were at a slight angle rather than parallel. Then the new drum went on and under very light application the shoes lined themselves up in the grooves, which made the corners of the shoes rattle or something when they pushed out of line. Anyway, went away after a couple of stomps.

So, brakes straight, drives straight, guess I'm set. These brakes don't quite have the "wow" factor of the last set I put on the Voyager though. What I put on that, have very progressive feel and bite really hard. These, not so much so far, hope they bed in a tad better.