What is a danger of having excessive pushrod travel when brake drums are cold?

Excessive pushrod travel when brake drums are cold can lead to a situation where the brakes may work initially but fail once heated. This phenomenon occurs because when the brakes are engaged, the additional distance that the pushrod travels may result in insufficient contact or engagement of the brake shoes with the drum. Under cold conditions, the brake components may not yet have reached their optimal operating temperatures, where materials might expand slightly and change the dynamics of their performance.

As the brakes heat up from use, the various components involved can expand, potentially altering the already excessive pushrod travel. This can exacerbate the initial disengagement, leading to a complete failure of the brakes to engage appropriately when they are needed most after having been heated by friction. Therefore, while the brakes may function correctly at first when cold, the excess travel can set up a situation that jeopardizes their reliability as temperatures rise.