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Extreme Veteran
Posts: 528
 
Location: Medford Oregon | I've replaced my front brake shoes, cylinders, and hoses. I'm still having problems.
1. When the engine is not running my pedal is a lower than I like, but is hard and doesn't sink. I plan on checking my adjustments for that, and would like to include adjusting the heal of the shoes. Is there a way for the home mechanic to correctly adjust the heal of the brake shoes? The old shoes were set with the arrow pointed towards the cylinders on all shoes.
2. When I start the engine the pedal goes almost to the floor. Any ideas on what would cause that?
Stanford |
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Expert
Posts: 3402
  
Location: Chestertown, NY ( near Lake George) | How were the brakes before the work was done? I assume you bled them? Start with the internal adjustments same as when disassembled, the do the major adjustment on the backing plates, till you get some lining contact, see how the pedal is, post back. |
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Extreme Veteran
Posts: 528
Location: Medford Oregon | I pulled both front hubs, inspected and adjusted the brake shoe heal (anchor bolt), reassembled and adjusted the brake toe. Here's the result.
The first picture below shows the heal adjustment. As you can see the arrow is pointed towards the drum. This should give the minimum clearance. After reassembly I adjusted the brakes so there was a light drag.
The second picture shows my foot on the brake with the engine off. The pedal is very slightly lower than the gas. I then started the engine and the pedal instantly drops almost to the floor (third picture).
 (FRHealAdjust.jpg)
 (BrakeEngOff.jpg)
 (BrakeEngOn.jpg)
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 FRHealAdjust.jpg (212KB - 107 downloads)
BrakeEngOff.jpg (162KB - 100 downloads)
BrakeEngOn.jpg (162KB - 102 downloads)
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Expert
Posts: 4046
Location: Connecticut | So when you shut the engine off, does the pedal come back up, or does it stay at the low position ?
When the engine is off, if you pump the pedal a few times, will it drop to the low position that it's in when you run the car ?
Have you measured your drums ? Book says, "When refacing, if brake drums will not clean up at .030, install new drums." This would account for low and lower conditions.
From diagnostic on power brake unit: "To determine if unit is operating, test as follows: With engine stopped, depress brake pedal several times to eliminate all vacuum from system. Apply brakes, and while holding foot pressure on brake pedal, start the engine. If unit is operating, the pedal will move forward when engine vacuum power is added to pedal pressure."
Ron
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Expert
Posts: 3402
Location: Chestertown, NY ( near Lake George) | How about the adjustment bolts on the backing plate as as a final clearance adjustment.Can you feel/hear lining contact as you spin the wheel? |
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Extreme Veteran
Posts: 528
Location: Medford Oregon | Ron - I didn't turn the drums as they didn't show any wear. The only reason I did the fronts was that a cylinder failed and contaminated the shoes. The new shoes have a slightly thinner lining than the old ones which would have a similar affect to turned drums of having to adjust the shoes further out.
In the test of the power brake unit I presume "forward" is towards the front of the car. Using that, the power brake unit is working.
Now, with all that said, I have my doubts about what the previous owner had done. Before this rebuild I replaced all the return springs because they were all weak, and then this rebuild happened after a cylinder totally failed in a panic stop. I don't think the heal adjustment was done then, and since the new shoes have a thinner lining that adjustment will have changed.
Dave - Yesterday I adjusted the front brakes as you suggested. Today I adjusted the rears as you suggested (which I didn't rebuild) and the pedal came up enough that I felt I could test drive it. It stops on light and heavy braking. I don't like the feel of the brakes, and want to determine how much of it is design and how much is something else. Thus the next questions.
Does your '55 have power brakes? If so, when you put your foot on the brake as you would in normal braking how high is the pedal compared to the gas pedal? If you push hard, how much further does the brake pedal go down?
To all - Nothing I have read suggests that the heal adjustment will affect the pedal height. Everything I have read suggests that this adjustment affects the contact area and wear pattern. This gets back to one of my early questions; is there a way for the home mechanic to adjust the heal?
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Expert
Posts: 4046
Location: Connecticut | You need to pull the drums and have them measured, especially since the linings are thinner than what they should be. Whether they looked good or not is beside the point. If there's not enough 'meat' left on the drums then you will have a low pedal and risk brake fade on a panic stop. Ron |
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Expert
Posts: 3402
Location: Chestertown, NY ( near Lake George) | Without the tool/caliper shown in the FSM, once this adjustment has been changed it is tough to reestablish, I used talcum powder on the drum to leave a trace on the lining contact area, you must back off the other adjustment to do this. |
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Expert
Posts: 1730
Location: Michigan | Have you looked at the adjustment of the brake rod coming off the top of the pedal mechanism? You could take up slack in the pedal travel. |
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1955 Chrysler Power Brakes
