master cylinder

[rfix'n]

Time for a new master cylinder. Before I buy the turbo version I have two questions
1) do I need a new booster as well, I understand the turbo is larger, will the turbo mc be as effective with the booster from my SC?

2) BA suggests the double MC pedal assembly from the 911SC RS, is there an advantage to this over the turbo MC?

I do plan on upgrading my brakes at some point and time but for now there stock SC calipers.

Thanks in advance

[Formerly Steve Wilkinson]

I happen to have replaced the booster when I went to a Turbo m/c in my '83 SC, since it needed changing out, but I replaced it with the stock booster. supposedly the Turbo m/c requires slightly more pedal effort, but I'm damned if I can tell. Can't tell if it's any more "effective," either...

Stephan

[Early_S_Man]

Rob,

The advantage to any dual-master cylinder setup is that the front/rear bias can be adjusted at the pedal assembly!

[ChrisBennet]

I would think that the Turbo (23mm) master cylinder would not be a good match for stock SC calipers. It would increase the pedal effort some I think. MC's are not that expensive, I would get the right size for your current setup and get a Turbo one when you upgrade your brakes.

I believe the SCRS dual pedal setup is non-boosted. IMO it is an expensive solution to a problem you probably don't have.

-Chris

[Formerly Steve Wilkinson]

The excellent and highly regarded independent Porsche shop that I frequent--Advanced Auto, in New Windsor, New York--routinely replaces SC-era m/cs with Turbo m/cs because bossman Tom Florio feels it's foolish not to. Having done so myself. on his advice, I can say that it seems to be an excellent match, on road and Lime Rock, for the stock calipers. "Thinking" that it wouldn't be a good match and actually trying it apparently are two different things.

Stephan

[Bill Verburg]

The 930 mc will cause the pedal effort to increase my ~25%. This should not be a problem for most healthy folks. If it was you could also replace the stock 7"vacuum canister with a larger 8" one to increase boost and obviate the increased effort of the larger mc.

As Warren mentioned the dual mc cylinder setup is only needed if improper basic bias exists and needs to be compensated for, or to trim for driver/circuit preferances

[ChrisBennet]

Originally posted by Stephan Wilkinson
The excellent and highly regarded independent Porsche shop that I frequent--Advanced Auto, in New Windsor, New York--routinely replaces SC-era m/cs with Turbo m/cs because bossman Tom Florio feels it's foolish not to. Having done so myself. on his advice, I can say that it seems to be an excellent match, on road and Lime Rock, for the stock calipers. "Thinking" that it wouldn't be a good match and actually trying it apparently are two different things.

Stephan

Thanks Stephan! That's why I wrote "think". See you at the Zone 1?
-Chris

[Wayne 962]

You are basically trading pedal effort for reduced pedal travel. Theoretically, there is no improved performance from the Turbo MC. In reality, I would even say that adding this MC would give you a *decrease* in braking power since more force will be needed to achieve the same effect.

You won't get any more performance in braking because you're not changing the pads or the rotors. This is simply a 'feel' thing, similar to adding a short-shift kit. I suppose if you did a lot of racing, and wanted a short throw on the brake pedal, then this would be a good change (change - not upgrade)...

-Wayne