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Old 11-20-2020, 05:40 PM   #1
Pilotdave
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Default Hard Brake Pedal - Update on Post #9

I am wrestling with a hard brake pedal issue. I decided to replace the steel drums in the car with cast iron in 2017. Drums were centered and turned. Shoes arced to the drums. System has been adjusted by several Model A mechanics, most recently last week. Worn parts were updated and shoes were re-arced. Still feels like I'm pushing against an immovable object when I step on the brake pedal. The car stops, but I am pushing really hard. This is very different from our other A's.

Today I tried this test: disconnected rear brake rods at the crossbar and test drove the car. Pedal was NOT hard - perhaps a little spongy. Reconnected rear brake rods, disconnected front brake rods at the cross bar. Same result. Reconnected front brake rods and drove it a third time. The hard pedal was back - along with the feeling that the car isn't stopping as fast as it should.

I've spoken with several knowledgeable Model A friends, searched on here, read Andrews Vol II - the results I found today are confounding them all!

I'd love to hear any ideas as to the cause of this problem! Thanks much.

Last edited by Pilotdave; 11-21-2020 at 12:03 PM.
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Old 11-20-2020, 07:04 PM   #2
Marshall V. Daut
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Default Re: Hard Brake Pedal

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Old 11-20-2020, 07:10 PM   #3
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Default Re: Hard Brake Pedal

Dave,

Saw this once with a transmission sagging in the rear enough to stop the full rotation of the brake cross shaft. Very hard pedal with limited brake rod movement.

One item to inspect.
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Old 11-20-2020, 08:00 PM   #4
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Default Re: Hard Brake Pedal

Thanks Marshall and JB-OB. I will check the cross shaft. Would a sagging tranny explain why the hard pedal disappears when only the front or rear brake rods are connected to the cross shaft?

Dave
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Old 11-21-2020, 10:30 AM   #5
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Default Re: Hard Brake Pedal

When only the front or rear brakes are connected maybe you are getting full travel of the rods. Combined the might be preventing full travel. I would check the rod length adjustments.
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Old 11-21-2020, 10:57 AM   #6
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Grasping at straws here.... When the brakes were redone in 2017, were the rear backing plates removed from the axle? There is a difference to the left and right plates. When installed the lever point upward and the clevis must angle in toward the center of the car a little bit. Perhaps they got switched side to side, and with the levers pointing upward, the clevis would angle outward instead of inward, which could cause some binding in the movement of the brake rod.
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Old 11-21-2020, 11:02 AM   #7
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Default Re: Hard Brake Pedal

Quote:
Originally Posted by Marshall V. Daut View Post
Check your "Private Messages" in the upper right corner of this webpage.
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The purpose of the forum In my opinion is to help everyone rather than one person. Please post answer rather than private message.
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Old 11-21-2020, 11:11 AM   #8
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Default Re: Hard Brake Pedal

Agree!!
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Old 11-21-2020, 12:02 PM   #9
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Default Re: Hard Brake Pedal

Here's an update. Today I enlisted the aid of my spouse to help me with a static test. She sat in the car and worked the brake pedal while I was underneath checking clearances and connecting various combinations of brake rods. For the most part, I disconnected rods at the cross shaft. Keeping in mind that testing the degree of pedal hardness this way is somewhat subjective, here's what we found:

1. The cross shaft is clearing the torque tube and the floor with considerable room to spare.
2. With all brakes disconnected, the brake pedal and rod to the cross shaft move freely.
3. There's no "hard pedal" with only the rear brakes connected.
4. The hard pedal partially reappears with only the front brakes connected.
5. The hard pedal fully reappears with all four brakes connected.
6. There's some hardness with only the LF brake connected; this increases some with only the RF brake connected.
7. With the brake rods fully disconnected at both front brake units, there doesn't seem to be any resistance when I pull the brake levers by hand on either front brake.

We then repeated the tests with me in the driver's seat....same results.

I realize that these results are different from what I originally posted. My apology for it I got anyone down the wrong path. However, I am wondering whether this MIGHT be a brake rod length issue. [The rods were all replaced last week.] Or more precisely, caused by differences in their lengths.

The backing plates were not removed when the brakes were updated in 2017. I will check the orientation of the brake levers and report back.

Thanks again for everyone's help.

Dave
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Old 11-21-2020, 12:04 PM   #10
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Default Re: Hard Brake Pedal - Update on Post #9

Check the rear motor mounts.
I once had a Model A that the brake pedal was VERY hard to push, found that the rear motor mounts were not holding anything and the trans mission was sitting on the cross shaft. I've seen it on other A's as well.
Easy check is watch the shift lever when you push the brake pedal, if it moves up you know that there's a problem.
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Old 11-21-2020, 12:17 PM   #11
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Default Re: Hard Brake Pedal - Update on Post #9

Thanks, katy. I've watched the cross shaft while my spouse was working the brake pedal - no interference to the cross shaft motion.

Dave
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Old 11-21-2020, 12:30 PM   #12
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Default Re: Hard Brake Pedal - Update on Post #9

I just did some work on my brakes so this is fresh in my mind. I would check the left front brake for some binding there. It could be that the wedge is hanging up or that something else is wrong. Take the drum off and operate the brakes without the rod connected. It should operate without any resistance.
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Old 11-21-2020, 01:49 PM   #13
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Default Re: Hard Brake Pedal - Update on Post #9

Are the front levers leaning forward about 15 degrees from vertical at rest, before you step on the pedal? If they are vertical, or leaning backward, that limits the amount of travel of the front rods, which would limit the travel of the whole system if everything is connected.
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Old 11-21-2020, 02:04 PM   #14
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Default Re: Hard Brake Pedal - Update on Post #9

nkaminar and Will - thanks for your suggestions. I did check both front brakes with rods disconnected at the brake levers and front wheels off the ground - I can spin the wheels and instantly stop them by pulling on the brake levers. No feeling of any interference on either side. Also have checked that both front brake levers are leaning forward 15 degrees with no play in the brake units.
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Old 11-21-2020, 04:19 PM   #15
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Default Re: Hard Brake Pedal - Update on Post #9

I would still be inclined to take the drums off at the front for an inspection of the mechanism. If there is nothing wrong at least you can put that question to bed. Re reading your post it seems like the problem is in the front. Did I get that right?
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Old 11-21-2020, 06:18 PM   #16
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Default Re: Hard Brake Pedal - Update on Post #9

nkaminar, I believe the problem is in the front. I'll pull the front drums and check.

Will, I checked the rear brake levers. They, as well as the photos in Andrews Vol I, have the clevis angled out toward the backing plate (see p 1-43). Maybe I am misinterpreting your comment?
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Old 11-21-2020, 06:43 PM   #17
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Default Re: Hard Brake Pedal - Update on Post #9

Dave, Two easy questions...

- At rest, the brake cross shaft is perfectly vertical ?

- What kind of material are you using for brake linings ?
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Old 11-22-2020, 07:47 AM   #18
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Default Re: Hard Brake Pedal - Update on Post #9

Quote:
Originally Posted by jb-ob View Post
Dave, Two easy questions...

- At rest, the brake cross shaft is perfectly vertical ? Yes

- What kind of material are you using for brake linings ?
Woven
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Old 11-22-2020, 08:56 AM   #19
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Default Re: Hard Brake Pedal - Update on Post #9

Dave,

Since it appears to be the front brakes causing the problem, yet you believe they work perfectly with out the brake rods attached.

Please share with us the technique you used to adjust the brake rods, especially the fronts.
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Old 11-22-2020, 09:41 AM   #20
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Default Re: Hard Brake Pedal - Update on Post #9

Quote:
Originally Posted by Pilotdave View Post
nkaminar, I believe the problem is in the front. I'll pull the front drums and check.

Will, I checked the rear brake levers. They, as well as the photos in Andrews Vol I, have the clevis angled out toward the backing plate (see p 1-43). Maybe I am misinterpreting your comment?



Aha, they should angle away from the backing plate. Think about it, the brake lever at the back wheel is further out from the center line of the car than the lever on the cross shaft is. The brake rod (in red in the crude sketch below) has to angle inward from the backing plate toward the cross shaft, so the clevis in the backing plate lever has to be angled to allow that.



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