I am rebuilding the braking system on my Series 61 sedan and am considering replacement of the single-circuit master cylinder with a dual for safety. Has anyone done this on a '49 and know of a suitable dual master cylinder that can be adapted with minimum modifications? Master Power (www.mpbrakes.com) has some useful information such as the use of residual pressure valves, etc., but I am looking for an application specific to '49 that someone has already tried with success. The original drums will be retained and I plan to keep it simple without adding power assist.
Thanks,
Sam Moore #21210
Sam,
I'm curious,is your MC mounted along the frame rail?I'm considering a dual for my 55 but prefer an easy conversion.(you know,a couple of days vs a couple of weeks!)...walt #23510
Walt,
Yes, my master cylinder is mounted in the same location on the frame as your '55. You should have a remote filler tube for adding fluid, whereas mine does not. I'm pretty sure that the master cylinder location was the same for '39-'55. Does yours have power brakes? If so, master cylinder pressure is transmitted to the power brake unit instead of directly to the wheel cylinders.
By the way, I was refered to the Modified Chapter Forum by a member. There is a lot of discussion there about dual cylinder conversions, but most of them were for more extensive mods than what I am planning, i.e. front disc, power boosters, etc.
Unless someone suggests differently, I assume that choosing a replacement dual cylinder is a pretty straight-forward process and that things to look for are a cylinder built for drum/drum systems, the same bore diameter, a deep piston hole for the manual pushrod, and whether or not the residual pressure valves are built in the outlets. Other than that, it should only be a matter of finding one that mounts the easiest. I have noticed that most master cylinders have mounting holes at the end, rather than ears on the side of the casting like the original cylinder. Seems that bracket fabrication would be easire with mounting holes on the side. I couldn't find the bore size in either my shop or parts manual, so I'll either have to disassemble mine and check it or see if a parts supplier's catalog lists the diameter.
The Rock Auto catalog only goes back to 1950 but it calls out a 1" bore for the 1950 master cylinder, same for 1955. www.rockauto.com
Sorry to report that I am essentially out of stock of the 1937-1949 mounting kits for mounting a dual circuit master cylinder in place of the stock single circuit master. I had only made 50 of these...