Brake failure in the evening rush hour

[Welding Will]

Hello everybody,

I'm Will and new here to the forum and hope to get some insight or proposals from you on how to handle the old red S1 HPE I shared with my brother over the last one and a half years already. And I'm looking forward to it ;-)

So, I had a brake failure and intend to revise the brake system of our old HPE in a moth (yes, no time before ) and as a newby to this type of work I would appreciate any hint I could follow.

The symptoms had been as follows:
- the Brakes had been overhauled five years ago, the fluid and the master cyclinder one and a half year ago
- so I drove through the city in the evening rush with working brakes - the brakes were rather cold at that moment, as I had just come from the highway
- when I stepped on the pedal I heard a louder, somehow hollow bang from the front left - right in front of me
- I had no pressure on the pedal at all for about five hastily performed pumps
- then the pressure on the pedal returned in the oldfashioned manner
- the system turned out to be absolutely free of any leaks afterwards

The guy from the brakedown service thought it to be the right rear caliper, because a small part of the brake pad was missing. He also mentioned that the car misses some of the brakepad-clips that hold them properly in place (each has at least one though). Could these small things really have that effect? I just cant't imagine it somehow. I dind't speak much more with the mechanic from the breakdown service as he didn't want to touch the system any further.

Any advice or ideas? My first suggestion would be to go for the mastercylinder, as it sits right where I had heard that sound.

Thanks in advance,
Will

[WestonE]

Hi Will

That is frightening! Get a Beta Haynes Manual and check you have 2 wedges per caliper with the clips that keep them in place. These wedges should be greased with copper slip so the calipers can slide. Check the pedal box to master cylinder connections are mot worn or broken. What you describe sounds mechanical. Obviously check for leaks of brake fluid all over the system. Brake fluid should be changed every 2 years because it absorbs water. So once you know you have sound system bleed through new brake fluid. Wire brush the threads on the bleed screws 24 hours before and cover them in anti seize fluid. They are prone to seizing and breaking off!

I hope this helps.

Eric     

[HFStuart]

Hi - do the brakes work OK now?

It is possible that one of the brake pads or the sliding caliper was seized in place and what you heard was it moving, the pumps on the pedal would be to move the pad back up to the disc.

I agree with Eric you should check to make sure the metal sliders are in place and that the calipers move reasonable freely.

Really pleased you didn't hit anything and damage yourself or the car!

Stuart