Early (69) Car, Carrera Brake Calipers...which Master Cylinder?

[rennch]

I've got to replace my master cylinder, which is a stock 69 911 T setup. I thought it would be a good time to upgrade if I had the chance. What's the hot setup for an early car with Carrera brakes?

[Eagledriver]

For the street, I'd stick with the stock 19mm. For racing I switched to a 23mm master. It makes for a hard pedal with lots of effort required. It works ok with high friction race pads.

-Andy

[jpnovak]

stock. The caliper piston sizes are the same diameter and you will have the same braking feel/force.

[rennch]

Ok...I thought a larger one was supposed to give me a better feel.

[djdsc]

The Carrera system came with a factory proportioning valve inline with the rear brakes. Installation is recommended when converting.

[Bill Verburg]

Originally Posted by emptyo

Ok...I thought a larger one was supposed to give me a better feel.

To a point, yes. But beyond that point no.

check to see what you have now some '69s had a 20.5mm m/c, very rare but very desirable.

Stock brakes would have been M/M w/ either 19.05 or 20.5mm m/c, the slave /master ratio w/ 20.5 is 35.674 w/ 19.05 it is 41.311 lower is better down to the low 30s beyond is just a lot of work w/ 23.8 it would be 26.467(too low for most people)

[Bill Verburg]

Originally Posted by djdsc

The Carrera system came with a factory proportioning valve inline with the rear brakes. Installation is recommended when converting.

only if you use Carrera 3.2 rotors and caliper f/r, Since the wider rotors aren't needed in back thesmart thing to do is to use Carrera 3.2 fronts and leave the back alone. W/ that setup you have a very nice f/r bias ratio w/o a p/v.

[Cory M]

I have driven Carreras with both the stock and 23mm master cylinders. Both cars had Carrera calipers, same brake pad compound, same tires, and weighed within 100 pounds of each other. This was on the same track in the same day. I preferred the stock master cylinder. The 23mm required a lot more force and provided less feedback before the brakes locked up. I would describe it as a smaller "window of operation" if that makes sense. The difference was significant. For the street I would rather have the immediate braking I felt with the stock master.

[rennch]

Ok...so I replace it with the stock master. Any thoughts on brake pads? I'm mostly autocrossing this car. I've heard thoughts of sticky brake pads in the *rear*, and stock in the front.

[rennch]

OH...and I guess I'm looking for a stock master cylinder now. WTB.

[Flieger]

I like the R4S.

[rennch]

Flieger, do you like them all the way around? Or just front/just rear?

[Flieger]

I use them all around. It is what Eric Shea recommended, and it is what my mechanic uses on his Time Trial 911.

[rennch]

Ok, thanks man!

[safe]

For the street and auto-x I don't think that you can go wrong with stock pads.
For track use I'm dead sold on Performance Friction, brakes good and lasts forever...

[Cory M]

Since you are considering Porterfield anyway you should call them up and ask their recommendation. They sell several brands including their own. In the past they have given a nice discount to NASA and POC members.