Front Brake Adjusting Shafts

[Bruce of MN]

In the process of putting it back together after replacing the kingpin bushings, I am having trouble with the rear shoe dragging when putting the drum back on. I have Flathead Ted floaters. The rear shoe's adjusting shaft has a loose fit in the housing for the wedge and jams in the bore. The front shoe shaft slides freely. I've cleaned the bore and the shaft and re-greased it and I still have to tap the shoe with a mallet to get it to move into position against the wedge. I backed the adjuster all the way and cleaned and re-greased it. The dragging shoe makes it tough to preload the wheel bearing and if the rotating drum doesn't nudge the shoe back a bit after releasing the brakes while driving, the drag won't be any good, either.

Bushing the bore can't be easy, even for a machine shop. Maybe a backing plate in better condition is the answer; any suggestions?

[nkaminar]

I have replaced the bushings in the rear backing plate. Press the old ones out and press the new ones in.

Make sure the cam can move back and forth easily in the shaft. A little grease helps here. You may need new parts.

[Bruce of MN]

Thanks, but I'm asking about the front brake.

[burner31]

It must be hanging up on something, take a slow long look (a cold beer may help in this situation)

[Jim/GA]

Originally Posted by Bruce of MN

In the process of putting it back together after replacing the kingpin bushings, I am having trouble with the rear shoe dragging when putting the drum back on. I have Flathead Ted floaters. The rear shoe's adjusting shaft has a loose fit in the housing for the wedge and jams in the bore. The front shoe shaft slides freely. I've cleaned the bore and the shaft and re-greased it and I still have to tap the shoe with a mallet to get it to move into position against the wedge. I backed the adjuster all the way and cleaned and re-greased it. The dragging shoe makes it tough to preload the wheel bearing and if the rotating drum doesn't nudge the shoe back a bit after releasing the brakes while driving, the drag won't be any good, either.

Bushing the bore can't be easy, even for a machine shop. Maybe a backing plate in better condition is the answer; any suggestions?

Yes, you need a new backing plate with less wear in the adjusting wedge housing. Also look for a lip formed by wear on the pin that is attached to the rear brake shoe; that lip can prevent the pin from sliding into the wedge housing.

How long have you been using Ted's floaters on that car?

[Bruce of MN]

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“How long have you been using Ted's floaters on that car?”

Maybe six years. I haven’t noticed wear on the shaft like that, but I’ll look closer and see what needs to be done.

[Jim/GA]

Originally Posted by Bruce of MN

“How long have you been using Ted's floaters on that car?”

Maybe six years. I haven’t noticed wear on the shaft like that, but I’ll look closer and see what needs to be done.

Wear on the adjusting wedge housing vs. on the pins depends on which metal is softer. Based on the wear you have seen, I suspect the housing is softer.

With Ted's Floaters, those adjusting pins slide forward and back with every application of the brakes, so the pins slide against the housing, with outward pressure being applied from the adjusting wedge against the tapered end of the pins. If the pins are not lubricated, something wears.

In Ford's original Model A brake design, the adjusting cone never really moves when brakes are applied, so the pins stay fixed against it (except when you adjust the brakes). With no real movement, the pins and the housing don't wear much. Ted's new design, where the pins slide, introduces a wear point.

[Bruce of MN]

I don’t see why the shafts would move every time the brakes are applied, wouldn’t the remaining spring hold both ends of the shoe tight against the adjusting wedge at the top and the actuating wedge at the bottom?

[Jim/GA]

Originally Posted by Bruce of MN

I don’t see why the shafts would move every time the brakes are applied, wouldn’t the remaining spring hold both ends of the shoe tight against the adjusting wedge at the top and the actuating wedge at the bottom?

Yes, the pins are held tight against the adjusting wedge at the top. With Ted's floaters design, the adjusting wedge at the top slides (floats) so that the braking friction on the rear shoe pushes the pins and wedge forward to also strongly activate the front shoe. That's how you get the really strong braking with the same pedal force.

Then release the brake and the pins and wedge slide back. It's a small movement, but it's repeated thousands of times. In the installation instructions, Ted says to make sure the pins and wedge will slide forward and back freely 1/4", and no upper "long spring" is installed.

Look at the geometry of the ends of the pins and the wedge. The rear shoe pushing the pin toward the wedge, which pushes against the other pin, pushes the pins out against the adjusting wedge housing. That's there the wear occurs. A little lubrication there helps.

[old ugly]

this is true. that original adjuster block will let the shoes sag down and drag on the bottom of the drum.
thanks for posting
i didn't know this cure.

[Bruce of MN]

Thanks, that makes sense and gives the Floater name! I looked at the offending shaft and it shows no wear and it was packed in grease, so it should have been well lubed.

Originally Posted by Jim/GA

Yes, the pins are held tight against the adjusting wedge at the top. With Ted's floaters design, the adjusting wedge at the top slides (floats) so that the braking friction on the rear shoe pushes the pins and wedge forward to also strongly activate the front shoe. That's how you get the really strong braking with the same pedal force.

Then release the brake and the pins and wedge slide back. It's a small movement, but it's repeated thousands of times. In the installation instructions, Ted says to make sure the pins and wedge will slide forward and back freely 1/4", and no upper "long spring" is installed.

Look at the geometry of the ends of the pins and the wedge. The rear shoe pushing the pin toward the wedge, which pushes against the other pin, pushes the pins out against the adjusting wedge housing. That's there the wear occurs. A little lubrication there helps.

[Bruce of MN]

Your teaching here has been invaluable! First, I played with the shaft positions in the housing to shift the wedge fore and aft and got it close. Then, I broke down and read the instructions, starting at #14! http://flatheadted.com/images/storie...winter2007.pdf That did the centering task and it spins nicely with the adjuster just backed off. I haven't driven it yet, but it should be fine.

Thanks again!

Originally Posted by Jim/GA

Yes, the pins are held tight against the adjusting wedge at the top. With Ted's floaters design, the adjusting wedge at the top slides (floats) so that the braking friction on the rear shoe pushes the pins and wedge forward to also strongly activate the front shoe. That's how you get the really strong braking with the same pedal force.

Then release the brake and the pins and wedge slide back. It's a small movement, but it's repeated thousands of times. In the installation instructions, Ted says to make sure the pins and wedge will slide forward and back freely 1/4", and no upper "long spring" is installed.

Look at the geometry of the ends of the pins and the wedge. The rear shoe pushing the pin toward the wedge, which pushes against the other pin, pushes the pins out against the adjusting wedge housing. That's there the wear occurs. A little lubrication there helps.