Here's the deal. My car's brakes drag. The symptoms are high pitched squeeling when driving down the road but no foot pressure on the pedal. The car just won't go, again no pressure. The car does not pull to either direction while cruising or braking. This happens only after the engine warms up and doesn't seem to be related to how much or hard I use the brakes. For example, I can have a perfectly normal brake pedal with 1-2" of free travel. I'll climb a hill and when I apply them again, there is no free travel what so ever and now I'm really getting on the gas just to go. I can pull up to a gas station, pedal feel normal, shut the car off for say 5 minutes, as soon as I get back in, the pedal is stiff with no free play. However, if it's cold out side and I'm moving, I can use the brakes quite a bit and the pedal feel stays the same, some free play, and there are no signs of dragging. At this point I'm hypothisizing that when the brake fluid heats up, it's not bleeding back into the master cylinder for some reason. Before adding a second pedal spring, I used to be able to occasionally relieve this by raising the pedal with my foot. However, that no longer works as the second spring ensures it's at the top of its travel.



The parts that have been replaced/rebuilt in chasing this are

Brake hoses
rebuilt calipers numerous times
new master cylinder
system bled and flushed with many bottles of brake fluid
An extra return spring installed on the brake pedal

While I think I was seeing to problems, the original return spring going soft and what ever problem I have now, I now suspect my current problem has something to do with the master cylinder or something not alowing fluid to bleed back into the ms when the car warms up.

Any insights would be appreciated.


Frank.
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'79 300D.

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'82 300SD