Confusing experience with brakes
Discussion
Originally, I put this in Suspension & Brakes. Got a couple of useful replies but there is not much traffic over there. So anybody here got some input?
The setup is twin Wilwood m/cs with ap discs and calipers. Car is only 1,500 miles from new. On Sunday 18th June in +30C, drove 130 odd miles out, parked for lunch, then set off for home. During the return journey the brake pedal went soft with long travel. System could be pumped up but braking effect seemed reduced. So I put the car away and planned to sort it out this weekend.
Before starting work I drove up and down the lane to refresh my memory. Pedal is rock firm and braking effect is perfect.
Anyone got any ideas as to what is happening?
The setup is twin Wilwood m/cs with ap discs and calipers. Car is only 1,500 miles from new. On Sunday 18th June in +30C, drove 130 odd miles out, parked for lunch, then set off for home. During the return journey the brake pedal went soft with long travel. System could be pumped up but braking effect seemed reduced. So I put the car away and planned to sort it out this weekend.
Before starting work I drove up and down the lane to refresh my memory. Pedal is rock firm and braking effect is perfect.
Anyone got any ideas as to what is happening?
Sorry to re-state the obvious but there is pretty much only 1 explanation for your initial problem.
For one of a few reasons you boiled the brake fluid, boiled brake fluid is a gas, gas is compressible & doesn't work as a hydraulic medium so you got a spongey/long pedal. On pumping the pedal you compress the gas which re-condenses mostly & works at reduced efficiency. Then overnight any gas left either completes condensing or works it's way out. The pedal is then fine, all you need to do is find out why the fluid boiled in the first place.
Reasons for the fluid to boil.
1. Over application of brakes.
2. Contaminated fluid.
3. Sticky pad/s.
4. Sticky piston/s.
5. Sticky slider/s.
For one of a few reasons you boiled the brake fluid, boiled brake fluid is a gas, gas is compressible & doesn't work as a hydraulic medium so you got a spongey/long pedal. On pumping the pedal you compress the gas which re-condenses mostly & works at reduced efficiency. Then overnight any gas left either completes condensing or works it's way out. The pedal is then fine, all you need to do is find out why the fluid boiled in the first place.
Reasons for the fluid to boil.
1. Over application of brakes.
2. Contaminated fluid.
3. Sticky pad/s.
4. Sticky piston/s.
5. Sticky slider/s.
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