Clare Snyder > wrote:

> If the shoes are not adjusted properly and the hand brake cable pulls
> the shoes out to where they belong (giving a decent pedal) the shoes
> are not on their anchors (depends on the type of brake) and any
> suspension movement CAN tighten the cable, initiating a brake
> application.

That must be it.

Once the leading shoe touched the drum, the trailing shoe must have been
forced to follow, causing the grabbing.

It must have been happening all the time, but only noticeable at speed.

Thanks for explaining.

My big mistake was in thinking the parking brake adjusted the "final"
position of the shoes.