Master cylinder from single piston brake car on 4-piston car?

need RX7 · 11-04-2010, 03:20 PM

Recently the brake master cylinder on my FC (5-lug, 4-piston front brakes) went out. I was in the middle of replacing it with the master cylinder from my other FC (4-lug, single-piston front brake car), when I remembered that people often recommend swapping master cylinders when doing 4-to-5-lug swaps, indicating that the master cylinders may be different.

Will I be okay running a single-piston brake MC on a 4-piston brake system? I'm not really concerned with optimal performance, since the car is a beater anyway, but will it work safely?

RotaryDiagnostics · 11-04-2010, 06:46 PM

I doubt whether the attachment points on the MC for the metal lines will match up.

need RX7 · 11-04-2010, 09:31 PM

Quote:

Originally Posted by RotaryDiagnostics

I doubt whether the attachment points on the MC for the metal lines will match up.

It will bolt up, but I was wondering if there was some obscure difference between the two (piston size, piston stroke, etc). Looking at Mazdatrix, they make no distinction between master cylinders for single-piston front and 4-piston front cars, so it looks like I'll be good to go.

rxspeed7 · 11-04-2010, 09:38 PM

Most commonly the cylinder bore size is marked on the master cylinder somewhere. if they are both the same and all the lines match up then you should be fine. I've never looked at the two next to each other and see if they were the same. Good luck

Zack.

11-04-2010, 03:20 PM	#1
need RX7 Clean S4 Nutswinger Join Date: Mar 2008 Location: Sterling Heights, MI Posts: 485 Rep Power: 18	Master cylinder from single piston brake car on 4-piston car? Recently the brake master cylinder on my FC (5-lug, 4-piston front brakes) went out. I was in the middle of replacing it with the master cylinder from my other FC (4-lug, single-piston front brake car), when I remembered that people often recommend swapping master cylinders when doing 4-to-5-lug swaps, indicating that the master cylinders may be different. Will I be okay running a single-piston brake MC on a 4-piston brake system? I'm not really concerned with optimal performance, since the car is a beater anyway, but will it work safely? __________________ -Ted -1986 Mazda RX7 Sport [DD/beater]: engine finally let go at 205k. parts car status. -1986 Mazda RX7 base [resto-mod project]: S5 n/a swap in progress.

11-04-2010, 06:46 PM	#2
RotaryDiagnostics Compression Tester Man Join Date: Feb 2009 Location: Mont Alto, PA Posts: 137 Rep Power: 17	I doubt whether the attachment points on the MC for the metal lines will match up.