Retrofitting dual master cylinder

[Jim Yount]

I've just finished a complete rebuild on my 65 327 with manual brakes. Since the car has seen/will see quite a bit of driving, I've updated the master cylinder from the single circuit that was stock, to a dual cylinder unit. The AIM shows the rear brakes being activated off the rear master cylinder piston. If both cylinders are the same size, does it make a difference which one activates the front, and which the rear? Is there a technical reason for doing this one way or the other?


I'd appreciate any input.


Thanks!


Jim

[Terry M.]

Re: Retrofitting dual master cylinder

Jim,


You don't say, but I assume you have upgraded using a GM master cylinder from a 67 or newer Corvette, and that your comments about what the AIM says relate to an AIM from the year the master cylinder came from.


The master cylinder piston is a two part (actually many more parts than 2, but for this discussion there are two major components) unit the front portion of which is pushed by a spring mounted to the rear portion. I believe the purpose of this arrangement involves how the two pistons work when there is a leak in one of the systems, but I might be wrong about that. It could also relate to which system (rear or front) gets pressure first. I believe best bet is to connect the way the AIM shows.


Did you install a pressure differential valve and light so that you will know when one system leaks?


Terry