Gus

Ok - I have found the solution to stepping the 10mm fitting up to a 12mm fitting size so you can do an easy install when changing over to a 993 MC. I found a 10mm to 12mm adapter fitting at a NAPA parts store and at a American Hydralic and Hose Store. I have posted pictures below of the fitting and the necessary modifications to make it work -
First the tip of the 12 mm fitting will fit right into the 993 MC - but the inside of the fitting for the 10 mm 964 tube requires a recess flare. This is very easy to change aas the 964 tube tip has a bubble tip - here you have 2 choices - you can cut off the bubble tip and make a recess flare or you can just stick the bubble tip in a flare device and change it to a recess flare by using the proper brake line flare tool. See pics -
Install the brass fitting in the 993 MC with Loctite 262 Permanent bond - thne just screw the 964 ( modified fitting ) into the adapter. that is it-
To make the change over on the tips you will need to remove the brake lines from the car - this can be a 2 person job as the lines run through the body work going into the boot area and require a 17mm wrench to hold the pass through fitting while you un screw the brake line from the underside of the car.
I have attached pictures of the 993 MC compared to the 964 MC and various pictures of the fittings so you can see what I am talking about. Look closely at the inside to the 2 brass fittings and you can see the difference between the recess and bubble seat as well as the tube tips for the difference.
Also - look at teh pic of the 2 MC sisde by side and you can see the difference in length as well as the difference in the MC end brackets. The pedal end of the MC's is the same. Also the diameter if the 993 is a little larger.
Hope that this helps folks somewhat -
Now to get on with the install - what fun.

Gus

Sorry - again I managed to get some pics sideways - just twist your monitor a little - Maybe some day I will figure that out.
OH! the 993 MC is the clean one on the left -

Robbie Ravioli

Thats a great post, I guess this will only work for the C2 as the C4 has the high pressure braking system.

ttAmerica RoadsterAWD

Thanks, Gus. Interesting. What does the 993 MC do better than the 964?

Gus

If you have upgraded your brakes to larger calipers- Like a look of folks have , the larger calipers require more fluid to operate effectively. The 993 MC provides a greater fluid flow - as it has a larger capacity- providing a more effect operation for the larger calipers. In my case I up graded to 993 calipers all around, but I kept the 964 MC. I was not pleased with the pedal pressure. So have installed the 993 MC to balance brake system.

Eugene-Taiwan

how is the pedal feel after the MC upgrade?