Front brake lever angle

Stingray70

Stingray70

Senior Member
Ok probably overthinking this but here goes:
When setting the front brakes, the book says the lever should be set to 15 degrees forward. 15 degrees from what? Kingpin? Perpendicular to brake rod? Vertical? I can't find a reference but vertical would be almost impossible to achieve.

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Stingray....

IF your backing plates, internal brake parts & cross shafts are correctly restored, the brake lever will sit at 15 degrees forward. You may need a single brake pill but any more 'tells' you, you missed something during the front brake restoration.
 
What I mean is to what line do I measure the 15 degrees? Vertical from the floor? That would not be accurate because the car could be sitting an infinite range of angles.

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Stingray70 said:
What I mean is to what line do I measure the 15 degrees? Vertical from the floor? That would not be accurate because the car could be sitting an infinite range of angles.

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Click to expand...

90° from the floor.
 
It does not have to be exactly 15 degrees. The purpose is to have the arm near vertical when the pedal is pressed hard so that the maximum amount of the rod force is used to activate the brake.

If you want to be exact, it should be 15 degrees from a perpendicular from the brake rod. So you could cut a piece of cardboard to 75 degrees (15 degrees less than 90) and use that to set the arm relative to the brake rod.
 
What you want is for the lever to be vertical with respect to the axle when the brakes are being applied. That will give you maximum pressure on the brake shoes to drum. Have one person step on the brake pedal while another person observes the lever. If it is vertical when the brakes are applied you are good to go.


How important is it to have the 15 degrees? What if you are off ? The force on the lever is dependent on the angle. At 0 degrees you get 100 percent of the applied force. The force is proportional to the COS of the angle. Thus at an angle (when the brake are applied) of 5 degrees you get 99.6 percent of the force. Or you are loosing 0.4 percent. If you are off by 20 degrees then you get 94 percent. I doubt that any brake system will be off by that much.


Bob johnson
 
These slides should help you understand the 15-degree angle:
 

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  • Front Brake Operating Lever Setup 137kb.jpg
    Front Brake Operating Lever Setup 137kb.jpg
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    Front Brake Operating Lever Setup 183kb.jpg
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I usually put enough pills under the actuating rod to take up more slack, making the arm lean forward more than 15 degrees. Is this reducing effective braking?
 
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