1926 Chysler 70 brakes

[Dan Richardson]

The front brakes have been replaced with disc brakes.  New master cylinder.  Rear brakes are original.  Rear brakes will not hold pressure and have been rebuilt.  Can the rear brakes be converted to use the new master cylinder?  Or is there maybe a better idea?  Thanks

[Leif in Calif]

Do you currently have two master cylinders or currently no rear brakes? Although your rear brakes are unlike any modern design, there have been many cars over the years that had a disc / drum set up. I'd check some of the hot rod sites...should be possible to just use your new master cylinder. 

[Leif in Calif]

After reading the very interesting information in the replies to your earlier question about this, I now think the characteristics of the original system are so different from a modern disc system, the only way you have a chance to make it work would be two master cylinders, one original and one new. Years ago (and possibly still) racing cars had two master cylinders (front & rear) so they could adjust the bias. 

 

earlier post: 

 

[Dan Richardson]

16 hours ago, Leif in Calif said:

Do you currently have two master cylinders or currently no rear brakes? Although your rear brakes are unlike any modern design, there have been many cars over the years that had a disc / drum set up. I'd check some of the hot rod sites...should be possible to just use your new master cylinder. 

There are two master cylinders one new and the old one is still there but not used.  The disc or drum conversion would be great.  Also maybe it would be possible to switch out the wheel cylinders to ones compatible with the  new system.  You thoughts?  Thanks

[Oldtech]

If it was mine... I would find a proportioning valve off a drum/ disc vehicle and hook it up and try it.  Not much to loose. a bit of inexpensive pipe and a junkyard valve.  If it's wildly out of balance then try a different plan.

[viv w]

If there are no leaks and the pedal goes down, then you have a problem with your master cylinder or its supply tank reservoir hole is blocked.

The rear brakes will work as they were originally designed , with externally contracting brake bands, but make sure you have soft woven linings and not modern hard linings.

 Also, I think you are foolish to expect the rear brakes to work properly with modern disc brakes on the front. Those external contracting brakes were not great when new and to expect the rear brakes to be efficient enough to slow the rear of the car as quickly as your front brakes, is to say the least suicidal, especially if the rears get saturated in heavy rain.

 If you are rodding this car with a V8 and lots of power then change out the rear brakes too, for the safety of not only you and your passengers but for other road users too.