Rear brake adjustment

[Mad Mac]

After re-lining the service brakes on the LHS rear wheel of my roadster pickup I went for a drive to check the adjustment. I gradually rotated the wedge adjusting screw in until the shoe just started to contact the drum.

I was surprised to find that the drum became very hot before there was any braking action. That seems illogical because, if the new lining is contacting the drum sufficiently to generate heat, surely any pressure on the brake pedal must instantly expand the shoe fully onto the drum? What am I missing here?

[J Franklin]

After adjusting till contact, back the adjuster off a click or two.

[bobbader]

Need more information. You only relined the left rear? You relined all but the left rear is the only one giving you a problem? Did you do the ebrake band as well? How well did the drum turn before any adjustment? Did you do adjustment with wheel & tire mounted to the drum?

[Mad Mac]

Reply to Bobbader:
I reconditioned only the service brakes on the left rear wheel, as all other brakes are working well including the e-brake which was not re-lined. After the service brake shoes on that wheel were re-lined, the wheel and tyre rotated freely when it was jacked up. Then I tested the brakes by skidding gently (at low speed) on a gravel road and observing the skid marks. The wheel with the re-lined shoes is the only one not showing a skid mark, so definitely not working. And that being so, - it should not be heating up!

Reply to J Franklin:
Yes, after the drum heated up I backed the adjuster off until I could drive without it heating, but there is still no braking action.

[J Franklin]

You will need to work with a helper pushing the brake pedal while you watch the action of the linkage and brake shoes. Did you forget a clevis pin?

[Mad Mac]

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Reply to J Franklin: - No I didn't forget a clevis pin - they are all there.

Reply to Jim/GA: - Thanks, I will check whether any of the clevises need adjusting.

Regardless of all your helpful comments, I am still left with the inescapable fact that the drum starts to heat up before there is any braking action. How can that possibly occur?

I have followed Les Andrews' recommendations all the way.

[Mad Mac]

On further reflection, I guess there is one way that it could possibly occur: The adjuster wedge is turned in sufficiently for the newly-lined shoes to contact the drum and generate heat, but the clevis adjustment suits the action of the old brake linings, which might delay the braking action. Comment?

[Jim/GA]

Originally Posted by Mad Mac

On further reflection, I guess there is one way that it could possibly occur: The adjuster wedge is turned in sufficiently for the newly-lined shoes to contact the drum and generate heat, but the clevis adjustment suits the action of the old brake linings, which might delay the braking action. Comment?

That is what it sounds like to me.

Many people will really bang the table "do not adjust the brake rod lengths" but I have found that sometimes that is what you need to get the 4 wheels braking the same amount without having the lining drag when the brakes are not applied.

Having said that, I have always replaced both left and right shoes/linings on an axle at the same time, never just one wheel. You may be making it harder on yourself than it needs to be.

[Mad Mac]

Originally Posted by Jim/GA

Having said that, I have always replaced both left and right shoes/linings on an axle at the same time, never just one wheel. You may be making it harder on yourself than it needs to be.

Thanks Jim:
The reason I replaced the linings on one wheel only, was because the lining on that wheel got covered in grease. I think I must not have used high temp grease when I did it a few years ago. I used high-temp grease this time.

[Mad Mac]

Originally Posted by Jim/GA

That is what it sounds like to me.

Many people will really bang the table "do not adjust the brake rod lengths" but I have found that sometimes that is what you need to get the 4 wheels braking the same amount without having the lining drag when the brakes are not applied. Having said that, I have always replaced both left and right shoes/linings on an axle at the same time, never just one wheel. You may be making it harder on yourself than it needs to be.

Acting on Jim's advice, I have now tried adjusting the clevis on the brake rod. Unfortunately there is not enough adjustment available before the threaded rod bottoms inside the clevis. Even after tightening the clevis up to its fullest extent, the shoes don’t expand fully onto the drum, so there is still no braking action. This is very strange, as the re-lined shoes must be thicker than the old shoes which used less of the available clevis adjustment. I must be almost there, because pulling the service brake lever slightly forward stops the wheel when rotated by hand.

[Jim/GA]

Originally Posted by Mad Mac

After re-lining the service brakes on the LHS rear wheel of my roadster pickup I went for a drive to check the adjustment. I gradually rotated the wedge adjusting screw in until the shoe just started to contact the drum.

I was surprised to find that the drum became very hot before there was any braking action. That seems illogical because, if the new lining is contacting the drum sufficiently to generate heat, surely any pressure on the brake pedal must instantly expand the shoe fully onto the drum? What am I missing here?

After major work like that, some of the adjustment is the adjusting screw. Some of it is in the brake rod clevis.

If you shorten a brake rod at the clevis to get it to brake more in time with the other wheels, you will probably have to back out that adjusting screw a bit, too. They work together.

[Rob Doe]

You may know all of this, but just in case:

Your hub may be fretting on the axle.

The axle key is in the axle, correct???

You had to use a wheel puller to get the rear wheel off originally, correct?

You washed until clean and dry, the tapered section of the hub and the tapered portion of the axle, cleaned and repacked the roller bearing, reinstalled with a new seal and the bearing retaining clip, then torqued to a least a minimum of 75 - 95 foot pounds, the axle nut, with the heavy, thick washer and its gasket, correct?

Some drive around the block and remove the wheel and tire to recheck that the nut is still tight.

The hub and the axle tapers are supposed to be smooth, clean and dry, no grease, oil or anti-sieze when assembled. When properly torqued at the nut, they act as a single unit to carry the torque of the axle to the wheel. If the axle nut is not adequately tightened, the key will wear and the key way will become loose. If the key carries too much load, the axle will eventually crack. If not discovered soon enough, the axle sometimes fails in such a way that the wheel, hub and drum leaves the car. Not good.

[Ernie Vitucci]

Good Afternoon...Can anyone show a brake adjustment board with dimensions for Mad Mac? Then he can follow the directions in Les Andrews red book, or Paul Shinn's, either one will work, and start with the brake rods loose and then do the work to get the shoes to hit the drumbs at the same time on all for wheels. Ernie in Arizona

[Bigsnapper43]

Years ago we had a worn bearing surface on the rearend housing. We ran with 3 wheel brakes. Not recommend!! Dont ask how I know.

[Rob Doe]

I suggest that all Model A Brake mechanics, especially the DIYer types, watch this video 10 times and then revisit it often. It is clear, concise and thorough. There is no stammering, stuttering or wasted words.

https://www.youtube.com/watch?v=3GFMJ7iiWiI&t=8s

[Mad Mac]

Originally Posted by Rob Doe

I suggest that all Model A Brake mechanics, especially the DIYer types, watch this video 10 times and then revisit it often. It is clear, concise and thorough. There is no stammering, stuttering or wasted words.

https://www.youtube.com/watch?v=3GFMJ7iiWiI&t=8s

Thanks Rob Doe,
Thats a great video - the best I have seen on the subject. Plenty to think about there, especially the last bit where he talks about adjusting the clevices on the brake rods. I will adjust the clevis on that rear LHS wheel, but not the others, as they are all working OK.

[Dino's A]

Originally Posted by Rob Doe

I suggest that all Model A Brake mechanics, especially the DIYer types, watch this video 10 times and then revisit it often. It is clear, concise and thorough. There is no stammering, stuttering or wasted words.

https://www.youtube.com/watch?v=3GFMJ7iiWiI&t=8s

Thank you, Excellent tutorial

[Y-Blockhead]

Are the shoes actually expanding when you step on the pedal? I may have missed it but did anyone mention the key (#12 in drawing) in the brake lever. Maybe it fell out during assembly? Easy enough to do.

[Mad Mac]

I think the Woodruff key you refer to is on the e-brake shaft, not the service brake shaft. Its the service brake shaft that I am concerned with, and that does not have a Woodruff key, as it is secured by a steel pin.

[Rob Doe]

Mac, reading your last post, I wondered if you had left the cam out of the camshaft.

But your last comment that forward movement of the lever with the hand was stopping the wheel makes me wonder if your service brake rod is connected to the cross shaft. You should not be able to operate the service brake lever by hand if both ends of the rod are hooked up properly?????

As I recall, the rear brake rod clevis is supposed to be at the cross shaft. The fixed end goes at the backing plate. Is that where you are adjusting the clevis?

How many clicks from completely backed off is your adjusting wedge?