OK, everyone. Pop quiz. Does a primary brake shoe have a longer or shorter lining than a secondary brake shoe? Time's up! The correct answer is it has a shorter lining. I find that very counterintuitive since most things called "primary" are larger than those called "secondary". Sheesh! I was operating under this assumption when I reassembled my front brakes and, as a result, I will have to redo them to swap the shoes. Arrrgh!

Now, believe or not, I tried to do my homework. I looked in several manuals and parts books but all the illustrations showed linings of equal size and the only references used in the manuals were primary and secondary. No explanation as to what the difference was. I guess you are just supposed to know or you don't have any business working on a truck. Well, that may be the case with me but it never stopped me before! I finally found a reference on a Raybestos online training web page with a pretty picture for me to look at.

I also tried using my parts truck as a reference but when I pulled the left front wheel off, the shoes were there but the linings were gone along with the star adjuster. What the?! There wasn't a bit of evidence as to where the linings had been on the shoes. Did the PO really wear them completely off? No help there. Let's pull the right front wheel, shall we? Cripes! ALL the hardware is missing except the wheel cylinder. I went into the woods for a few minutes to cry where Dad couldn't see me. While there I contemplated jumping into a pile of thornbushes because, quite frankly, that sounded like more fun than I was having.

So, I ended up putting the primary shoes with the small linings where the secondary shoes with the big linings were supposed to go and vice versa. I'm bummed.

Kevin Kessler
1953 Ford F-100

 

Look on the bright side, this time around it will only take you have the time to remove and install On a serious note, I remember someone saying it doesnt really matter if they are reversed.

 

From my experience it doesn't matter. I bought an old Ford years ago and happened to notice that the shoes were reversed when I was repacking the front wheel bearings. I had been driving the car for thousands of miles and the shoes were only about half gone. So, there's no telling how far they had been driven that way. Did I change them? Heck no. The brakes worked great, so I left well enough alone...

Vern

 

Thanks for the Raybestos link. Basic level information like that is often hard to find. It's now saved in my favorites for later reference.

 

You wouldn't believe how many people don't know what goes where. I got a new axle out of the wrecking yard and when I got to looking at the brakes, both primary shoes were on the left side and both secondaries on the right. Also had some hardware swapped. Easiest way to remember is that primary is first (or front), secondary is second (or back). Also, secondary is longer name=longer pad. Something else people don't realize is that the adjuster lever and the star have a left and right and are stamped as such.

 

It is my understanding that the short shoe is for braking in reverse and the long shoe is for braking going forward. Since we tend to do more driving forward and more braking, there needs to be more material for a larger area of contact.

 

Here's some info not mentioned. The primary brake retracting spring is installed before the secondary spring. Does anyone know why? I don't.

 

I know this post is really old but here is my guess. If you install the springs the other way, the primary shoe spring sits outboard further on the anchor pin and tends to pull the shoe away from the backing plate. The shoe won't sit flat against the backing plate so it winds up crooked and dragging in the drum.

 

The rotation of the drum is a big part of what makes the brakes work. The shorter shoe (primary) goes to the front and is shorter becuase it actually has less of the stopping force applied to it. The whole brake shoe and spring assy pivots off the top pin. As the brakes are applied the primary shoe makes contact and the turning force of the drum tries to rotate the whole brake assy, thereby forcing the the longer shoe (secondary) into the rear of the drum. So, not only do you get braking force from the action of the wheel cylinder pushing out at the tops of both shoes but the rotational force of the drum acts to force the rear shoe into the drum.

I recently went through the search to find which shoe was the primary and the secondary as I was upgrading my 1960 9" to have self adjusters from a 1969. Usually when I work on a drum style system I only take one side apart at a time, that way if you get interrupted or forget or whatever, you can always pull the opposite drum and check see how it all goes (unless of course your other side is a complete mess or your parts truck is missing everything)

Bobby

 

I have spent a lot of time turning wrenches, and I never really realized the thought that goes into some of the processes. I was always taught that the big lining goes to the rear. I never questioned it, because it was my dad that taught me. For me, there has never been a better mechanic in existance than my father. If he said it was so, then it was so. I guess I'm glad that my dad knows what he's talking about, especially since I have gained so much from him over the years, and with some college, and a lot of shop experience I find myself stumping even some of the best mechanics, and answering their questions for them. I remember a few years back, I applied for a job at Schucks, and they weren't sure if they were going to hire me until an older woman came in with questions, and I was the only person in the store able to correctly answer and explain everything to her. They later took me in for the computer test interview, and I recieved a perfect score. Anyhow, I was always taught the big n!@@#$ sits in the back. (to quote my fathers explanation).

 

Bobbytnm..your explanation of how the drum system works hit it right on the money...and saved me typing it..thanks

 

SSHHHH!!!! don't say stuff like that out loud!!! I have a reputation to keep and it wouldn't do for people to know I can actually give a correct answer...

I'm glad it was helpful
Bobby

 

Hey Bobby, do what I do..when I get one right I treat myself to a trip to the junkyard..

 

I just picked up one of those Haynes Series Repair books on brakes repair and it had a great description of the physics involved in leading/trailing brake shoe pads and the size mismatch.

 

How much of a Headache was it to put the Self-adjusters on?
How are they working out?
Please post Pix of them installed.
I remember Father doing the Up-grade on our '60 Ranch-wagon & F-100 when the Self-adjusters 1st became available as an Option, but I just don't remember how easy or difficult it was to put them on, as he was rather Stoked about Not having to crawl under & adjust the brakes by hand anymore.