Brake master cylinder

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Is this the one you most use?

Yes and the pushrod is 120mm long total, 40mm threading M10 x 1.5 and 80mm smooth rod (8mm Dia) with a hemisphere tip.

I just machined another 1/4" thick alloy firewall Brake plate for the Factory MC and here are the dims. Just use the same 80mm top to center positioning when your brake Pedal is drilled upwards by 1.00"

This will get you started, and what's nice is you can cut the hole to the larger diameter later on for the Wilwood Tandem and the Pushrod is the same ....

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sort of related to the FW plate...
Even though I have bought a Wilwood tandem for my set up, I would like to know what is wrong with using the porsche brake master cylinder? If I recall correctly, the bore of a stock MC is about 0.9" and the Wilwood is 1.0".

There are several variations of the OE master/pressure valve set up. All are dual circuit with the front brake bore diameter larger than the rear. The '86 turbo MC was 23mm/20mm.

The OE set up might be sufficient depending on which calipers that you use. I am guessing that those who convert to the Wilwood MC have changed the calipers or want the larger bore to shorten pedal travel. An adjustable proportioning valve would be needed since the Wilwood has a single bore diameter.

When I did the GT3 brake upgrade I created a spread sheet to compare piston cylinder area of the front/rear caliper set ups so I could tell whether the MC I was using would work. It was an interesting exercise because the piston area of the 6 piston front/4 piston rear set up on the GT-3 was just a hair larger than the Turbo S stock set up. The difference in stopping power, however, comes from huge front pads/rotors and rear pads that are a hair smaller than the front pads of the Turbo S. The point of the rambling is that the OE 951 MC could be used with many applications depending upon the calipers used.

The willwood tandem feels great with the big LS430 front calipers and rx7's on the rear. I moved the pivot point up 1"... I stomped on them pretty hard yesterday.... I can't believe how different the car is with the new engine and brakes!!

Spence, glad to hear that your combination works as I have the same.

Have just resolved another problem, there is a strengthening strut that supports the firewall behind the brake master cylinder. This strut runs paralell to the pushrod/clevis assembly and after moving the pivot point up .75", the clevis was fouling the strut. I managed to squeeze an angle grinder in to relieve the edge of the strut. I also reversed the clevis pin to make it easier to remove the pushrod when the MC is installed

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Had to do something similar to mine, I moved it up about .90 or so.

What about the clutch... can I use the original Porsche master cylinder? Or dou you use wilwood?

You can use the original but i think most are using a 13/16in tilton or wilwood MC.

Is the tilton m/c better?

I would not think one is better performing than the other. Mine are Tilton, because that is what came with a dual MC bought off of Ebay. Wilwood's are less expensive.

Ok thanks I guess I will use my original. Hope I can put everything together in this week