FedEx just dropped off a care package of some goodies needed for my rolling pile of Joy.

The old brake shoes for rear drum brakes have a primary and secondary shoe, the forward shoe having the shorter lining length to aid in the servo action. The Centric replacements are 4 identical shoes, did they make a mistake?

edit: Just checked out a set O'Reilly had in stock here in town. Same thing all shoes identical. Hm.

 

Typically the front shoe doesn't need to be the same length. I can't see there being a problem because they are though. But yeah - I've done easily 1000 brake jobs by now and that's a first for me.

 

Well they seem pretty thin too for new shoes. It's a pretty common brake shoe, used for a long time. Monroe BX55 for example. Many different manufacturers offer a variation with the number 55 these are Centric 112.00550

 

I don't know if the same length would effect anything, never tried it. Are the shoes bonded or riveted? It seems bonded are a little thinner then riveted.

 

I bought centric shoes for my 64 f350... They had a primary/secondary however the old shoes I took out did not, they were all 4 the same size.

 

The different length shoes are for a reason and part of the bendix design. During braking the primary shoe in front tends to rotate along with the drum and away from the top anchor pin and through the adjuster link transfers this force to the secondary shoe and basically jams the rear shoe in tight against the drum and anchor pin. The secondary shoe is thicker for this reason.

That's why they are called "self energizing" duo servo brakes, because the braking force that results is much greater than the pedal force required. Whether this characteristic is diminished by using equal length shoes, I don't know. I would expect so since Bendix did it that way for a reason. But, maybe it makes no difference, the different length linings was a cost saving measure, and expense of making and stocking different shoes is today too much trouble and they are now made the same length. The new linings are riveted, the old ones bonded. I'd reuse them except they are probably oil and brake fluid soaked and don't want to trash the new drums.

 

That same p/n probably fits many applications now, not just Fords.


I put them on my 66 and they worked fine.

 

I don't doubt that at all. But the question is, maybe they would work even better, when they are setup as primary and secondary. At least I got everything pretty much buttoned up, going to bleed everything tomorrow and take 'er for a spin.

 

11" x 2" front brakes & 11" x 1 3/4" rear brakes: 1948/52 F1 - 1953/67 F100.

Pic from 1964/72 truck parts catalog. Self adjusters introduced in 1964 F100 2WD.

 

Thanks ND!

What's the deal with the double long spring, 2035? The kits don't have it, my brakes don't have it, the Shop Manual shows a picture of it, but doesn't acknowledge it, except in the text references it as an "assist" spring. Just a curiosity is all. Was it deleted at some point?

 

Notice that the parts catalog pic is generic, besides 1964/72 F100 2WD's, also applies to 1964/72 Econolines, P350/400 Parcel Delivery's, 1967 F100 4WD's & F250's.

So, your F100 doesn't use the long 2035 double spring, uses the 2035 secondary (black) & 2036 primary (red) springs instead.

Originally in order to ID which spring was which, they were painted specific colors.

 

Well the 64 Shop Manual shows it in the F100 and P100 photograph, they list each component by name with an arrow pointing to it, except that one, a bit confusing is all.

 

Left: 1964/67 F100 2WD 11" x 1 3/4" rear brakes in application chart / Right (scroll down a bit): 1st page of parts list #2 showing 2035 & 2036 springs.

 

Well the brake job is basically done and I would rate them as good to excellent. With all new parts, they should be. One thing that I noticed though that a couple people touched on. While the stopping distance is reasonable, with hard braking to purposefully (carefully) get them to lock up, the rear brakes do so first.

Or maybe "only"; The shoes aren't completely broke in, but the fronts wouldn't seem to lock up. Not much weight in the truck. I realize there is no proportioning valve in a single pot drum/drum system, the rear wheel cylinders are 7/8ths and the front wheel cylinders 1", and the OEM M/C is spec'd at a 1 and 1/16th" bore. The replacement is listed as 1" bore.

That's the proportioning right there, apparently. All four wheel adjusters are set with some drag - is it safe to increase the front wheels a bit more, so they (in the extreme) lock up first and/or simultaneously? Rear wheel lockup is usually mentioned as both bad, and normal or typical. So what's up with that?

I also understand that generally speaking wheels locking up is not desirable at all. But want these brakes to be adjusted as close to optimum as possible prior to them locking up. See where I'm goin' with that? Maybe this is as good as it gets. That's why I'm asking.

 

Adjustment will have no effect, the pressure equalizes in all the cylinders regardless of where the adjustment is. Driving with these old style drum brakes is some what of an art. They aren't idiot proof like modern anti lock brakes.

I would look further into why the OEM master was 1 1/16" and the replacement was only 1".