Musings on brake squeal

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Stradageek
Posts: 1657
Joined: 17 Jan 2011, 1:07pm

Musings on brake squeal

Post by Stradageek »

Having just solved the latest caliper brake squeal problem I found myself musing on the fundamentals of brake squeal, the key observations being that, once cured, a non-squealing brake is a little less powerful than a squealing brake but also less prone to lock-up.

So I find myself speculating that, fundamentally, a squealing brake is one where braking friction will cause unconstrained brake blocks to bounce off the rim in any way and at whatever frequency the brake mechanism will permit.

A rapid lock-up will result when the vibrations that are (like ABS) modulating the braking power, suddenly cease (as the mechanism becomes more constrained under hard braking) and full friction is applied.

The solution must therefore either constrain/align the brake blocks so that they cannot 'bounce' off the rim, or reduce the braking friction.

In my most recent two cases exchanging oil contaminated brake blocks for clean blocks and moving to different (lower friction) brake blocks, immediately solved the issues. The slightly poorer braking performance was compensated by a reassuring absence of lock-ups under hard braking.

Just musing :wink:
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