27-28 Chrysler Master Cylinder

jquam · 4 Weeks Ago

Can someone help me out with the bore and stroke dimensions of a '27-'28 Chrysler Master Cylinder...external contracting brakes

Thanks

John

James R. Lesniak · 4 Weeks Ago

I just checked the master cylinder from my 1925 Chrysler Six B Phaeton and bore diameter is 1.625", the stroke is approximately 3 1/2". My guess is the 1927 70 should be the same, as it too has external contracting brakes. Be sure to have the cylinder sleeved with stainless, with hone and polish that looks like a mirror, which is imperative if you plan to clean out your lines and cylinders, and use silicone fluid. Silicone fluid seems to creep through the slightest finish imperfection less than a mirror finish! These brakes impress me with their stopping ability with modern brake lining, mine were bonded to the bands. Adjust clearances to the drums per the owners handbook section on brakes. Be watchful on your first times out, and feel the brake bands for heating up. If so, increase the clearance to drums. These will wear in and be easier to adjust as you put a couple of hundred miles on the new linings. Jim Lesniak, Seattle

jquam · 3 Weeks Ago

Jim, thanks for the quick reply and information.

The Chrysler brakes including front and rear axels were actually retro fitted onto a 1923 Paige Dual Cowl Dual Windshield Phaeton back in the late 70's and the car has been in storage till now. A modern dual port master cylinder with vaccum booster was installed at the time. I think the MC is a drum/disc type.

The wheel cylinders and MC have been rebuilt and bled, however, in order to stop you must pump the brake pedal a couple times and then you only get under an inch of pedal with very little stopping power. The brake bands have only very slight movement when you step on brakes.

My thought is the current MC setup does not have enough volume to fully engage the brakes. I think if I went to a single port, larger volume MC and got rid of the vaccum booster (I'm not sure there is enough vaccum to operate) the brakes should work.

Any thoughts??

John

James R. Lesniak · 3 Weeks Ago

I also would suspicion that not enough volume of fluid is produced from this modern cylinder. I was able to get my spare master cylinder apart today, after freeing up the stuck piston. The piston is 1.160" long, then add .175", the thickness of the rubber cup. There is a stop at the bottom of the cylinder and a return spring that pushes the cup backwards against the piston. Fully compressed, this is 1" long, so the way I figure it, maximum stroke is right at 1.485"! This is not a lot of stroke, but with a 1 5/8 bore, it moves adequate fluid to work the brakes. My original guesstimation of stroke was more the bore length, as seen from the outside of the master cylinder casting. It was impossible to see the internal components and get an accurate measurement computation of stroke. Jim