master cylinders for porsche brakes

[dgluyas]

:silly: I have Brembo 944 turbo calipers and need to know has any one used a stock 19mm master cylinder with these and did it work? I have heard a 23mm one from a 944t will work well (obviously) but some say a twin turbo one will give the right bias? Do we need to run a brake booster or will it work ok as is? I have currently 944 steel calipers at the rear and standard fronts that run well but have heard the standard m/c wont cope with the fluid requirements of the big reds? Any one got any experience?

[MattKab]

Hi, I run 944T Brembo 4pots, front and rear. I'm still using the stock master cylinder and I can confirm that it DOES displace enough fluid for proper operation. Absolutely no sign of any bias problems. However, I only have less than 50bhp and I'm losing some brake energy in the old flexi-hoses and will be fitting Goodridge braided replacements. This may reveal any bias issues........fingers crossed!

One thing I've noticed on my voltmeter, I can see the volt-drop across the brakelights and in normal, slow braking conditions, like moving upto a busy junction. The pedal effort required to activate the pressure switch is much higher. I can stop my car without the brakelights coming on. I intend to fit a reed switch and relay to the pedal, in paralell with the pressure switch. Less hassle than going through a box of old switches to find a weaker one, eh?

'hope this helps,

Matt \X/

[Steve Arndt]

I had the same brake light sensor switch sensitivity problem with 68 rear and ghia front brakes on a normal m/c. Good idea on a fix. I replaced my old switches with new and they swtiched with slightly less pedal pressure but not good enough.

Steve

[Superman]

The research that I have done (reading) shows that most are happy using the VW M/C with the Turbo [4 piston] calipers and the Porsche M/C with non-turbo brake calipers.

[Steve C]

Hi

Im using 996 rears on the front (got 'em cheap) and Boxster rears on the rear (surprise) and my stock MC works great. Tried a 21 mm and couldnt stop the car when it was cold.

MattKab Try flushing your the hole in the your pressure switch with some metho, they do glug up.

I have found an odd thing happens a traffic lights, sometimes my car will roll, even though I think I have my foot on the brake.??
Steve C

[MattKab]

The addition of Goodridge hoses appears to have remedied my brake light issue Steve, thanks for the tip.

Highly recommended. Forever guaranteed too.

What specification brake fluid does everyone run?

I'm using dot4- works well, what is standard brake fluid for the 944T?

[Murdock]

I would use some of that super blue brake fluid, comes in 1 liter cans I believed imported from Germany. I got my 2 liters from ebay at 10 bucks a pop.
I have the same problem with my ghia that the brake lights wont come on until I basically am at a stop - very dangerous especially at night. I have read that the old rubber hoses will swell almost - shut somewhere in the middle and because of this it is like having a restriction on the brake line, causing greater pedal effort to displace the fluid.
Just in case I have a new vw m/c, brake switches and DOT approved stainless steel brake hoses in the mail. ;)