brakes dragging

[weq92f]

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Welp it's now happening to me...Noticed a drag then chased it to the front discs. Both front calipers are dragging too much. The drag on each side is equal.

Here's the twist...it doesn't drag once everything cools off. It doesn't drag until everything gets up to temp. I can't duplicate on the "bench" with it idling and me randomly pushing on the brake pedal for a while then holding it for a while, etc. and so on.

I'm thinking this is caused by pressure not releasing rather than both calipers having an issue simultaneously. Note also this brake dragging is a new thing without having made any changes to the system. But...a while back one of the lines to the master came loose and I lost brakes. The repair to that consisted of only attaching the line and pouring more fluid in. Given this...I think it's probably the proportioning valve.

What do you all think? How do I go about diagnosing the valve?

Thanks,

-weq