In this picture you can see 3 master cylinders. The one on the left (in the picture) is for the clutch. The one closest to you on the right (in the picture) is the FRONT brake master cylinder. The one furthest away from you on the right (in the picture) is the rear master cylinder. If you read the size on the master cylinder for the front brake master cylinder you can see it reads .700 or 11/16" bore.
Rear brake master cylinder is .750 or 3/4" bore.
The clutch master cylinder is .700 or 11/16"--just like the front brake master cylinder.
You can see in the below picture a little fitting that comes on all of the Wilwood master cylinders--straight out of the box. (I am pointing to it in the above picture). We throw them straight in the trash. You won't need them. Also, Joe got a little bit ahead of me assembling this pedal box and you can see the front brake master cylinder already has the brake reservoir fitting in it. On the master cylinder, the front opening (the one furthest away from the push rod) is a #4 o-ring boss fitting. The other side of the fitting is a #4 JIC which connects to the brake reservoir cans. There is no pressure on this fitting. It is simply where the brake fluid enters the master cylinder from the brake reservoir cans. If you get the billet reservoir can option on our list, then your brake fluid will not be rusty when it enters here.
