When the truck hasn't been driven for a day or so,I have about 1/3 of the pedal's travel free,then a good firm pedal;it gets a little less freeplay each time I use the brakes,and after the second or third use the brakes seem to start to drag worse and worse.
Something else that occurred to me-if the master cylinder got moisture in it,could some water contamination make the brakes do this,or would water heat up and make steam,making the pedal drop instead? Or maybe gear oil contamination is gumming things up to a point that nothing's returning.
I'm getting a longer and longer list of "needs" on this truck. On the "Plus" side,since I got into it as a trade,I'm not out much $,so I can probably swap the motor,do ALL the brakes,gaskets and seals on both axles,replace the smashed left door,weld up the cab,give it a new windshield,etc. and be happy with the results. It'd STILL be a rolled,rusted,banged up Toyota truck,but it'd be solid,reliable and road capable,and the "patina" (to put it very mildly) would be a DEFINITE attention-getter. The work it needs would be a couple of years of work,but now I have reliable transportation again,so I'm okay with it.
Speed