Service Brakes - 2 Thoughts

[Bob Bidonde]

For what reason should a Model "A's" brake drum be cut?



My thinking is that a brake needs to be cut if it gets out-of-round.


If the braking surface of the drum becomes grovey, I would not cut the drum for this reason alone. The groves actually increase the braking area.



What brake shoe lining material is better, molded or woven?



From experience, the black molded lining material (riveted-on) is inferior to the woven lining material:

• The molded material wears much faster and produces a lot of brake dust;
• The coefficient of kinetic friction of the woven lining material is higher, so braking is better;
• Woven linings last longer;
• Woven linings wear grooves into the brake drums.

[Chuck Sea/Tac]

The drum becomes glazed. Sometimes you can use rough sandpaper and deglaze. Shops of course take .010” off.

[Dick Steinkamp]

Originally Posted by Bob Bidonde

For what reason should a Model "A's" brake drum be cut?



My thinking is that a brake needs to be cut if it gets out-of-round.


If the braking surface of the drum becomes grovey, I would not cut the drum for this reason alone. The groves actually increase the braking area.



What brake shoe lining material is better, molded or woven?



From experience, the black molded lining material (riveted-on) is inferior to the woven lining material:

• The molded material wears much faster and produces a lot of brake dust;
• The coefficient of kinetic friction of the woven lining material is higher, so braking is better;
• Woven linings last longer;
• Woven linings wear grooves into the brake drums.

Could you please provide the data and the source. If only your opinion or personal experience, please say so...

1. The groves (I think you mean grooves) increase the braking area.

2. Molded linings wear much faster.

3. The coefficient of friction for woven linings is higher than for molded linings.

4. Only woven linings wear grooves in the drum.

[Bob Bidonde]

Dick,
"My thinking is that a brake needs to be cut if it gets out-of-round." "From experience, the black molded lining material (riveted-on) is inferior to the woven lining material....."



What is your contribution to this opinionated dialog?

[Purdy Swoft]

If the brake drum is out of round it will cause the brake pedal to pulsate when the brakes are applied .

[Dick Steinkamp]

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Originally Posted by Bob Bidonde

Dick,
"My thinking is that a brake needs to be cut if it gets out-of-round." "From experience, the black molded lining material (riveted-on) is inferior to the woven lining material....."



What is your contribution to this opinionated dialog?

I was hoping you had some back up data and/or references.

Thanks for clarifying the source for your conclusions and recommendations.

[Synchro909]

I think Bob is spot on with the first part of his post and I have nothing to confirm nor contradict the second. Many drums are turned for no good reason.