I have lost confidence in my car last year due to brake issues all season. For some u known reason on a few occasions I hit the brakes and there was nothing there as if the pad had moved and I had brake knock off, I decide to fit a brake prop valve to see if this sorted the issue. As the issue was very inconsistent I could not tell if this sorted it. Another issue I came across was when I blead all the brakes i had a really good pedal. When I then turned the car on, the pedal would go soft. I noticed the pedal does go harder after a few pups but then goes soft again when held down. I have now stripped my car ready for next year and noticed than someone has fitted what would seem to be a DC2 brake servo and I presume a bigger master cylinder. Could this be my issue or could there be an issue with the diaphragm inside?


i also noticed that the very first pedal pump i can hear a hissing air sound and when i release the brake pedal i hear a little squeak, is this normal? I have full Braided lines throughout the car that are fully sealed and no visible leaks from the connections. Do you think having a bigger MC and Brake servo could be part of the issue? thanks for your reply, Dave.


I really don't want anymore brake issues this year! Please advise as I have limited knowledge on these cars.


Many thanks, Dave.

I have attached a few pics of my servo and master cylinder below;

 

If you got this setup use its most likely damaged. Did you bench bleed the master cylinder? Did you hook up the vacuum line to the brake booster? If you had to rebend the brake lines were they done properly? Did you bleed all wheels after the install? Did you think that just swapping them in they would fix there own problems on its own?

 

Well first of the brake booster seems to be working because its supposed to be hard when the car is off and then will get slightly softer when the car is on because the vacuum is being applied there fore doing its job.

But with the hissing sound when you let off the brake pedal sounds like something to do with the booster vacuum source. I would start by replacing the vacuum line that runs to the brake booster. It sounds like the likely culprit and is the easiest and cheapest place to start.

 

thanks for your replies. I re fitted all the brake hoses are bled the whole system more than once. As said I managed to get a stiff pedal with the engine off but when I turned the car on the pedal went soft as if the servo is too big for the standard brake setup.


The hissing sound I believe came from the bias valve (tiltson) and apparently the sqweek is also common.


All brake lines are new and are HEL lines. so there shouldn't be any issues with the brake lines. Can you please confirm to me what the brake booster is?


Thanks, Dave.

 

big black round thingie

 

The break Booster is the item on your first 2 pics, the black one, and he is referring to the hose that goes from the booster to the engine admission manifold....

 

Thanks for the replies. I was referring to the booster as the servo sorry. I have just picked up a standard 15/16 master cylinder and standard booster. Hoping this will eliminate the problem. I have been told the booster (servo) could be the issue as I'm running standard brakes with a bigger DC2 servo and MC.