Brake question
 

Taken from Les Andrews book..."The rear brake shoes need to be centered to the drum in the horizontal plane. This will allow the arch of the shoe to fit the full arch of the drum"....
My question: I have my brakes and they have been rebuilt with all new parts. I'm getting new cast drums. If I have the drums trued and then the shoes arched to the drums is the centering necessary?

Re: Brake question
 

Read over this previous entry to Fordbarn

https://www.fordbarn.com/forum/showthread.php?p=37150

On a quick thought I would say no. That is providing you have arched the shoes correctly. Still, I might use a dial indicator and check your shoes for concentricity before you apply the drum.

The first time you apply the brakes the double ended "cam" slides in the shaft hole and automatically centers the shoes, and takes up all the lost motion around the shoe clevises and pushes the clevises to the adjustment wedge/cone.

After this first application is where you might want to try a little bluing on the inside of the brake drum. Find out exactly where the high spots are on the shoes and verify full contact. If you have 75 to 80 percent contact and it's at the "center" of the shoe, I would consider that acceptable for arching AND centering.

Some actually "relieve" the shoe a bit at the leading edge of the shoe if found touching. Maybe 20 percent of the total shoe surface. This to prevent brake squeal and lead to better wear-in.

Joe K

Re: Brake question
 

JoeK,
A common practice that I always did, was to arc the shoes .010" LESS than the drum diameter, to eliminate squeeling/squeeking in the initial "settling" in of the lining, thus eliminating the need to "relieve" the leading & trailing ends of the linings.
Bill W.

Re: Brake question
 

Heh. Makes sense. Strongest contact at the "center" of the shoe. I took a file to my shoes to get what is in essence a smaller diameter.

Of course I haven't mentioned the story I read about "lining" the brake drum with sandpaper held there with picture framer's spray-tack, and then on assembly "turning" the drum and moving the lever to abrade the shoes at the high spot first. The OP wasn't asking about that.

What thickness is sandpaper when you consider the grit? Maybe 0.010? And when the sandpaper is removed what do you have?

I love it. Practical mechanics of the most practical kind.

Joe K

Re: Brake question
 

I fit my brake shoes to the drum this way I use 80 gritt self stick sanding board paper to line drum. Seem to work for me.