anyone know how to read brake lining codes?

Hi Nate, Check the 3 flats on the backing plate where the sides of the brake shoes make contact. If these areas are grooved, pitted, badly worn or heavily rusted it can cause the brakes to grab like you describe. That's an often overlooked problem on old cars. On something that old it wouldn't hurt to rub your sandpaper on those contact areas anyway and get them nice and smooth.

-jim

N8N wrote:

All of the backing plates look pretty good. The areas you describe are near pristine. I have driven cars with significant grooves in that area that stopped better than this one. I'm about at my wit's end with this, got a couple more things to try and then I will have to slap in a prop valve I think. Not sure why I am having this issue. Anyway I was told by a friend that sells big truck brakes that the "FF" is the important part of the lining edge code and that means that all the linings are nominally about the same coefficient of friction so that is likely not my problem.

nate

(becom> Hi Nate,

Follow up question: is it possible that I am having this issue because my rear shoes are still pretty fresh and the fronts appear to be about

nate

N8N wrote:

You have your leading and trailing shoes all facing the correct direction don't you?

How do you adjust the brakes on this one? Do you have one center adjuster or one adjuster for each shoe?

Steve B.

sure hope so... little ones to the front...

Typical self-energizing brakes, with a manual star wheel at the bottom. When adjusting, I run the star wheels until i can't tighten them any more and then back off 10 clicks, then fine tune so the wheels spin about evenly

nate

The adjusters could be in backwards so when the brakes are applied, the shoes are being adjusted closer to the drum causing the lockup. But all the gunk on the rears cannot be cleaned off. The wheel cyl cups need to be replaced, and maybe the axle seals (I don't know whats leaking), and remember, the short shoe is always to the front....

snip post about rear brakes locking up...

This is just a wild ass guess, but IF the drum diameter of the rears is much smaller than the fronts the rear brakes will apply first and may lock up.

I think I'd replace the front linings and check the drum diameters before spending lots of money and time trying to fix this.

They are manual, no possibility of that

There is no gunk on the rears

axle seals were replaced before the shoes

yes they are...

nate

I will attempt to extract what I see as the relevant info from your statement.

What you are saying is that this problem of grabbing brakes didn't develop over time as you drove the car, but instead, it all started when the new rear shoes were put in.

If that interpretation is correct I would guess the shoes are not the right size. That would mean either not the right width or not the right radius. You should be able to see the wear pattern on the shoes. Is it contacting only in the center of the shoes or only at the ends? Also, If the shoes are a hair too wide they could be pinched between the drum and backing plate when applied (the same could be true if the drums were turned but not cut quite wide enough).

-jim

The problem is that this car is a "barn car" that I am in the process of putting back onto the road; it has a Texas inspection sticker on the windshield reading "0" and that means that it's been off the road for at least six years, more likely 16 or 26. When I got the car the brakes were in bad shape, the linings were worn, mismatched, and fluid soaked in the front. I replaced all shoes at that time, along with the hoses, master cylinder, and three wheel cylinders (the fronts needed to be replaced; the rears appeared to be able to be "kitted" but one had a stuck bleeder screw so it was replaced as well.) The brakes were only "driveway rated" at the time I got the car so I haven't a clue how they performed when the car was last on the road.

The reason the rear shoes are newer is about 50-100 miles after I started (carefully) driving the car I ran to a parts store maybe 5 miles away to exchange a battery and as is my habit I set the parking brake in the parking lot. Apparently due to a missing spring in the parking brake linkage the rear shoes were dragging slightly as I drove back, not enough to create a perceptible drag but enough that there was a distinct smell of hot linings by the time I parked the car again. Post mortem revealed minor heat cracks in the rear linings, so the rear shoes were replaced again. This is why the front shoes are older than the rears, but none are actually "old." All were obtained from the same vendor and as I posted above appear to be consistent in their friction characteristics.

To answer your specific questions, I don't have a drum caliper but little to no perceptible ridge is evident on any of the drums. The front shoes appear to be contacting the drums more or less fully, but as the rears are pretty fresh they are only contacting the drums over maybe 30%-ish of their surface, mostly on the leading and trailing edges. I can only ASSume that this is because the friction material is thicker than stock but the drums are still relatively unworn. I would assume that shoe width is not a problem as they are stock relined shoes and the friction material does not hang over the edges of the shoes.

Unfortunately I don't have the option of going to a deserted parking lot and properly wearing in the shoes; I live in an area where such things don't exist and traffic is such that trying to "burn in" the brakes on public roads would likely result in a ticket, accident, or both. I also don't know of any shops that have the ability to "arc" my shoes for me to speed this process along...

thanks for the reply...

nate