Hi, This should be an easy question> It has been awhile since I did any drum brake work. Does the "short" shoe belong on the front side on both driver and passenger side? This is on rear drums if that matters. This is were I have it now on a disc/drum set up and constantly have a problem with the back brakes locking up too soon.
the shorter one should be forward side of car.......primary shoe is shorter..secondary shoe longer... **for shorter(primary) shoe drivers side ....on left side passenger side....on right side...
To fully understand why the shoes are different, one has to also grasp why the return springs are different tension. That's our quiz for the day. JW
The operating term here is "self energizing" or "servo action" The primary and secondary shoes are also of a different composition. When you apply the brakes, they move with the drum until the one shoes is stopped by the anchor pin. Then the other shoe is stopped by the star adjuster. They are also forced outward at the same time. They kind of wedge them selves against the drum. Thats the brakes are grabby when you reverse the shoes I think this was on my ASE test years ago
Yes.. Simply put, the forward shoe reacts first to the wheel cylinder pressure, and comes out an meets the drum, due to the fact it has a lighter return spring on it. This pivots the entire brake shoe assembly and uses the energy of the spinning drum to pivot the assembly into the back of the drum, and mulitply the force applied to the larger rear shoe. Instead of simply answering the question, a full understanding of how the drum brakes work will help you realize why it's important to lubricate the backing plate to shoe contact area with so the shoes can pivot freely. This is also why correct brake shoe adjustment is important. JW
wow, thanks guys. This is why this board is great. by the way, I replaced all the return springs and pins last night with new. It made a noticeable difference.
I make it a habit of dabbing some anti-sieze on the six pads. Whatever you do, make sure you use the correct brake spring tools. Never use a screwdriver to install the springs. My ex boss knew a guy he worked with who tried to pry the springs on with a flat blade screwdriver. The screwdriver slipped, and he wound up sticking the screwdriver into his eyeball. And i dont mean he poked his eye with it, the screwdriver was in his eyeball. Needless to say, he's down one eyeball.
The "pads" are really shoes and crack because of the heat and the quality of the materials in the shoe. You generally find the riveted shoes don't crack.
brakes 101 Also worth mentioning- Make sure when you replace shoes that you have the drums measured and turned on a lathe. Drums that have been machined too large wear the shoes unevenly. You want a perfectly smooth surface on the drum to match the smooth surface of the new shoe. If the drum is too large- discard it. The lathe tends to make "record player grooves" in the surface. Take a piece of 80 grit sandpaper and sand the drum surface. As the drum is spinning on the lathe, sand the surface with a back and forth motion. Your trying to achieve a non directional finish. Vert important on brake rotors as well. Shoes and pads need to wear themselves in. Thats why when you do brakes (especially fronts) the brakes feel like they're "gliding" to a stop. As you use them, they gain more and more friction. A complete brake job is more than just replacing shoes or pads
