Re: 1953 Patrician: has anyone updated from Treadlevac to modern 2-chamber mstr cyl?

Posted by Ross On 2022/7/14 7:57:00

The TV piston has an area of only .44 square inches so a press on the pedal of 100 pounds yields almost 230 psi. A typical modern piston has an area of .88 and will yield only 113 psi. And of course the booster can add up to another, oh, 300 lbs pressure to the piston if you really stomp it yielding up to 800 psi brake line pressure.

My estimate is that Packard sold almost 150,000 cars with Treadlevac as it was a popular option. It was also installed on many other makes including Continental and Mercedes.

They work great with a very short pedal travel in normal driving. In an engine-fail emergency, they are no different than any other vacuum assisted power unit. You have to press hard. The only weak spot in the design is that they will not tolerate dirty lumpy brake fluid.