1995 Subaru Legacy, 170,000. Brakes get tight and lock up after 10-30 minutes in traffic in hot weather. The first sign is that the car doesn't coast freely. Then, after a few minutes I have to downshift more and more to get the car to move. Often after a complete stop, the car will not move at all. Engine seems to be fine. Pads, calipers, master cylinder all have been replaced recently. This has been going on for over a year. Several mechanics have not been able to find the problem. I recently moved from NY to Alabama where the hot weather is making the problem worse. Oil gaskets have also been replaced. Clutch was replaced before this started happening. I hit a NYC pothole right before I moved here, which caused a slight dent in the left front rim. Now, when the brakes lock up, black smoke comes out from inside the left front wheel. However, the brakes were locking up before the rim was bent. Please advise!