by Hans Efde » Thu Aug 06, 2009 4:54 pm
Concerning the silicone based brake fluid I recall my collegue had difficulty getting the pedal hard. It felt like there was air trapped. Whatever he did, he could not cure it. In the end he flushed it all (was a time consuming job as well) and switch to standard brake fluid. I don't know what the present standard is, I suppose Dot 3.
Concerning brake problems locking brakes when they are warm (and release when they are cold again) is likely caused by the vent hole blocked by the master cylinder piston. Seized or dragging brakes (due to long standstill etc.) are ususally caused by dirt and corrosion. Hot or cold brakes won't differ.
My problem was a soft pedal and appalling brakes. I tried everything and even took the master cylinder apart (which was fine). As a shotgun approach I got rid of the brake servo by removing it and replacing it with an adaptor plate. I wrote about it in one of the previous club mags. This solved everything and gives the car great brake feel. Obviously more brake force is needed, but I can control it perfectly. Also no play between the pedal and the master cylinder. There is instant action.
In theory a Midas should brake as well as a Metro, because all geometry is retained. But recently I had a chat with Ed whose blue coupe wasn't braking as well. There seemed to be a large dead stroke. He had replaced almost everything,including the brake servo. In the end I suggested to remove the master cylinder (just unbolt and lift, the brake lines are flexible) and put a cap o.e. on the pin that was sticking out the brake servo. This lifts the master cylinder brake piston slightly and removes play. He noticed that now the brakes would bite much earlier at the pedal stroke, but they didn't drag or seize when being warm.
Brake problems have been reported more and it seems that somehow (using parts from different cars?) play may be introduced between the pedal throw and the upward movement of the master piston. It's worth checking this, by jacking up the car, hand rotate a front wheel and let someone slowly apply the brakes. When the wheel starts dragging, check how much travel of the pedal was needed. This dead part should be as small as possible,