Originally Posted by L-Pink

I was going to give a serious answer until I saw the post and was reminded he shouldn't be driving at all.

Anyway, On real hot days, less heat is able to escape from under the hood. Extra heat in the master cylinder can cause the internal bore to slightly expand. If the cup seal inside the bore is worn the bore expands from the heat and the seal starts to allow the brake fluid to by-pass it and the brakes become softer than that big spot on JohnnyClips head.


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