Front brake shoes grab

[Keith]

Front Brake grabs violently when applying light to medium pressure when coming to a stop. This occurs when first starting out in the day and with a few hard quick stops it sometimes will go away for most of the ride occasionally coming back. The front brakes when applying also sound like a Mack Truck coming to a stop in that the squeal quite load.

I am running new cast iron drums with the brake shoes fitted to each drum. The linings are woven with brass wire. I have replaced all the internals, new springs, new rollers and pins, new star adjusters and tapered pins on the ends of the shoes and tracks. I also filed a nice leading taper/edge on each end of the linings.

Question: If the shoes are slightly off center will this cause the grabbing? I have access to a brake centering tool but do not know how to correct the centering if it is off. Someone mentioned bending the tracks, but they are hot riveted to the backing plates.
Keith

[nkaminar]

The tracks are key to centering the shoes. If they are worn then you will have to weld them up and file them to get the shoes centered. This can be tricky because the tolerance on the shoe centering is very tight. Bending is a quick fix but not the best.

The trailing shoe has a degree of self actuating where the friction will add to the force applied by you. This can cause the shoe to grab. I would guess that this is worse when the shoe is not centered.

Without centering the shoes by fixing the tracks, there are a couple thing you can do. I rode in a car that had good brakes and the owner told me that he centered all of the shoes by riding the brakes for a while. This wore the brakes to the point where they were centered. Another thing to do is to install a Flat Head Ted Kit. That kit will make the shoes floating so that they are self centering. The kit also reduces the amount of pedal pressure needed by making all the shoes self actuating.

[BRENT in 10-uh-C]

Originally Posted by Keith

Question: If the shoes are slightly off center will this cause the grabbing? I have access to a brake centering tool but do not know how to correct the centering if it is off. Someone mentioned bending the tracks, but they are hot riveted to the backing plates.
Keith

Keith, bending tracks is very hard to do even using a torch, AND is a bandaid for something else that is incorrect.

The Brake Centering tool is basically a check gauge to tell you something is wrong. In my shop, we don't use one because we don't need to. The issue with the track misalignment is two-fold. To begin with, Ford did not allow their Agency (Dealership) mechanics to replace or install the A-2017 Brake Centering Brackets onto the Brake Housing Plates because there was a 0.0025" allowance for misalignment. In layman's terms, that is about the thickness of a human hair. When the holes in the bracket and the holes in the plate are factored in along with the 0.247-0.249 diameter of the rivet, we have found you can be off as much as 0.030"-0.040" in either direction (too high or too low). That is why you MUST use a fixture to align the replacement Centering Brackets (tracks). It is also worth noting the dimension given in Les' book is incorrect. If the location of the brackets are incorrect, no matter how much the bracket is bent, ...or no matter if the head of the pin is shimmed, you are never going to have properly functioning brakes.

Also, many of the brake shoe cores are out of specifications and need to be restored. The holes in the A-2023 Rollers are supposed to be reamed (-not punched) to a diameter of 0.4375 (⁷⁄₁₆") and the corresponding hole in the brake shoe is to be the same size. If my memory is correct, the pin has about a 0.001" - 0.0015" clearance fit. This means there should be almost no wobble detected.

So my point in stating the above is just because you have thrown new parts at the braking system does not ensure you will have properly functioning brakes. Additionally we have found the A-2042 Adjusting Shaft lengths can vary and be out of specs. The operating Pin length is often incorrect, and even the Wedges can be shaped incorrectly. In your case, my guess is that you have a show that is too low and grabbing.

[Rob Doe]

Thank you Brent for those accurate names and dimensional details.

You can send your backing plate to Snyder's or other professionals, and they will put new parts on it, including new tracks. Or they will sell you a new set of tracks and spring hanger, rivets. The old have to have their head removed and the new have to be heated and hammered on.

[Bob Bidonde]

Flathead Ted's Brake Floaters will significantly improve the braking performance of your Model "A," and negate the need to have your brake shoes centered. His floaters enable the shoes to find their own center in the drums. You should also check your brake linings for high spots.

[Will N]

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Make sure that the four bolts holding the backing plate to the spindle are tight. A loose backing plate can cause the brakes to grab.

[J Franklin]

Nobody mentioned that grease or other contaminants on the linings or drum can cause this to happen, especially when first using the brakes.

[nkaminar]

Keith, Since you have all new parts, the assumption is that there is no grease anywhere. If some grease was introduced when you assembled the brakes then it has to be removed.

As Bob and I have both said, the Flat Head Ted Kit is a good way to go for a number of reasons. You will never get the accuracy that Brent talks about at home.

One other thing to try is to glue 80 grit sandpaper to the drums and then abrade the shoes by moving the adjustment out while turning the drums with the wheel attached. Auto paint shops sell sand paper that is self adhesive.

The chalk trick that Bob showed is another good way. A belt sander will remove the high spots. Do not breath the dust, wear a mask.

Will had some good advice in Post #6.

Here are sources for the standard FHT kit and the deluxe kit: https://www.snydersantiqueauto.com/p...7549&cat=41655, https://www.snydersantiqueauto.com/p...7547&cat=41655. In my car I did not feel the need for the deluxe kit. Snyders has instructions on their site.

[Phil Brown]

Don't forget to put a small angle on the ends of the shoe linings insted of a 90 deg. cut
Thats most likley the source of any noise and or squeal, but could also add to the tendency for the brakes to grab

[Benson]

Brent,

About post #6:

I can see where using "big Box Store" bolts with no shanks might be a problem with incorrect alignment.

Are the Repro sets like these correctly manufactured to hold backing plates in alignment?

https://modelastore.com/brakes/brake...roduct_id=3157

[BRENT in 10-uh-C]

Originally Posted by Benson

Brent,

About post #6:

I can see where using "big Box Store" bolts with no shanks might be a problem with incorrect alignment.

Are the Repro sets like these correctly manufactured to hold backing plates in alignment?

https://modelastore.com/brakes/brake...roduct_id=3157

If you are referring to the Front Backing Plate Bolts, then actually it is the hole in the middle of the Brake Housing (Backing) Plate that pilots using the Spindle's flange to hold the Plate firmly and in alignment. Theoretically, any type of bolt (keyed or not) would work as far as holding the Plate and Baffle firmly to the Spindle.

[Benson]

Thanks for reply.

I missed the fact that this was about front backing plates ...

Sorry ... xin lỗi

[bobbader]

I dare say we might need more information. You said the shoes were fit o the drums. So they were professionally "arced" to size? Did you install (or have someone else install) new roller tracks? Was the entire brake system rebuilt? Was front end work done as well? Is it possible front end work needs doing?

If you set up the brake rods, how did you adjust the fronts in relation to the front actuating levers?

If you were to jack up the car, set both axles on jackstands, had someone sit in the car and hit the brakes, would they grab evenly, side to side? front to back?

There's a lot that goes into diagnosing brake issues, especially if you've replaced many of the parts. Some more background might help.