Brake balance

[Tomas lopez]

Im from mexico, and we are building a 1969 911T for the carrera panamericana 2011 how dificult is to intall a brake balance device?

[Flieger]

If you mean a dual master cylinder setup wih balance bar, I think it is not too difficult, just rather expensive if you buy the unit from Fabcar or 901 Shop.

[MarkS]

If your looking at using the existing single master cylinder and installing a device to simply control front to rear brake bias Tomas they are inexpensive $60-100 USD and easy to install.

Google up 'brake proportioning valve'

[Flieger]

Those are pressure limiters, not the same thing as brake bias.

[RSTarga]

Tomas is going to do the Panamericana with this car. He needs the twin master cylinder option in my opinion. Hola Tomas!
Thought I saw these units available like what was on the SC/RS.

[RSTarga]

Flieger is correct. 2100dls
http://901shop.com/main/CustomProduc...5/Default.aspx

[edmayo]

The SCRS unit puts the master cylinders inside the car with all of the brake lines that would then make a mess inside the should you ever need to remove them. Porsche used to put the master cylinders outside where the original master cylinder is. I bought a unit made by a shop, whose name I forget, years ago that puts the cylinders outside, I'll take a picture of it tomorrow, never installed it, too many other projects kept interfering. In the meantime here is a picture of such a unit on a 74 3.0 RS.

[MarkS]

Those are pressure limiters, not the same thing as brake bias.

I undersand what they are, they allow you to change F&R brake bias correct?

[Flieger]

They put a limit on the pressure that can be reached on one circuit, so below that activation pressure, the bias is whatever the master/slave/piston hydraulic advantage ratio is. Once that pressure is reached, the pressure stays constant on the limited circuit while the other one keeps climbing, so below that point the bias is more rearward and above that point the bias becomes more and more towards the front.

That is my understanding anyway. There are some good graphs around. The pressure limiter makes a "knee" in the curve while the bias bar changes the slope of the curve.

[chris_seven]

With the SCRS box you will have to make a couple of holes for the fill pipes but other than this you can ususally bolt the box directly into the standard location and no other mods are needed. It is interesting to see that the above photograph of the RSR style box also has the fill pipes inside the car.

The RSR box will also need a section of the floor cutting away and replacing with a welded -in flat section which will allow the two master cylinders to side by side outside the passenger compartment.