Big brakes, do I need to upgrade the Master Cylinder?

[8vMatt]

Hi guys,

I've fitted Porsche Cayenne rear Brembo's 4-pots on the front of my car, I was expecting a bit of the old head through the windscreen kind of braking. But thats not the case at all. There is loads of pedal travel until it bites and no confidence in it. There is some sort of whoosh noise when the pedal is pushed.

I've had a couple people say about getting a bigger master cylinder and sort of understand about the amount of fluid moving around etc.

The car is a VR6 Corrado, is there a Golf master cylinder thats bigger than my one? Or anyone know of anything else I could look at?

Cheers all.

[Wayne]

Sounds like they need bleeding tbh.

[sharki786]

Sounds like they need bleeding tbh.

+1 was thinking that aswell

[8vMatt]

Been bled prob about 3-4 times now. Just had the brake regulator changed and the garage bled it today. No better than though. What would this whoosh noise be? Its sounds like a movement of air. What could cause that?

[Wayne]

Been bled prob about 3-4 times now. Just had the brake regulator changed and the garage bled it today. No better than though. What would this whoosh noise be? Its sounds like a movement of air. What could cause that?

They need to be bled with a pressure bleeder.

[8vMatt]

I don't know how the garage did it but one time when we bled the system, I guess it was a pressure system. The guy used a line connected to an inflated car tyre that pushed the fluid through the lines. We kept topping up the chamber when needed. I saw the bubbles coming out of the back calipers, loads of them.

Do you guys think bleeding is the issue even after 3-4 goes at it?

[Wayne]

I don't know how the garage did it but one time when we bled the system, I guess it was a pressure system. The guy used a line connected to an inflated car tyre that pushed the fluid through the lines. We kept topping up the chamber when needed. I saw the bubbles coming out of the back calipers, loads of them.

Do you guys think bleeding is the issue even after 3-4 goes at it?

Yes it sounds like air in the system.

[Agreeable Slick]

It's either that of you have a split in one of the lines or the brake cylinder.

[Santiago]

...What would this whoosh noise be? Its sounds like a movement of air. What could cause that?

That would be movement of air into the brake servo from the cabin.  This happens every time you brake, but because of your excessive pedal travel, is now noticeable. 

Nice little explanation here: http://www.kfz-tech.de/Engl/Bremskraftverst.htm