Dual brake conversion

[KULTULZ]

Try this one the guy made them thought it was the correct link here -

Please understand. I am mot yelling or anything of that sort.

I only want to help you.

There are no 'ONE FITS ALL BRAKE CONVERSION KITS'

If you decide to use that MC (GM CORVETTE DUAL DISC) (true bore size undetermined) on a DRUM/DRUM INSTALL, both brake line outlets will need an in-line #10 RESIDUAL PRESSURE VALVE. No other valving will be needed if an original OEM DRUM BRAKE SYSTEM (unless wheel end brake sizes have been altered).

VALVE EXAMPLE - https://mpbrakes.com/product/vl3710k-10-lb-residual-valve/

Any other questions please feel free to ask.

[Gene]

Chuck, why would he (or anyone) need 10 lbs residual valves if the mast is up on the firewall?

[KULTULZ]

Read this and if any questions feel free to ask -

https://mpbrakes.com/how-to-series-brake-valve-overview/

Their description is not entirely correct; While the valve will hold pressure on the piston cups, the actual purpose of the valve is to allow the brake cylinder piston cups not to flutter on return when pedal is released and while retracting allowing air into the system or fluid being expelled. With air in the system and/or leaking fluid, you will not have correct pedal action (soft/low).

These were used until the 1971-1972 model year and were replaced by wheel cylinder piston cup expanders. The system (drum) has to have one or the other.

[rmk57]

  I went through the opposite issue when I replaced the master on my 1970 Mustang which has a disc / drum setup. The replacement master was from a 68-72 Ford F100 which is a direct replacement for mine. After it was installed and bled I took it out for a test drive. I didn't get 1/2 mile from home and the front brakes started locking up, barely made it back home. Turns out the master was for a drum / drum application and with the rubber check valves in the front it wouldn't release the calliper properly. Took it back off pulled out the brass seats, removed the duckbill check valves re-installed and all is well. Turns out Dorman uses the same basic master for both applications.

[KULTULZ]

Turns out Dorman uses the same basic master for both applications.

One has to be very careful where one sources parts nowadays as most is off-shore junk.

And don't trust kit makers either as most are either un-knowledgeable or uncaring.

[rmk57]

  The only difference in the m/c between the two is whether they had the rubber check valve behind the seat. Used to be able to tell a drum / drum m/c just by the equal sized resivours, not anymore.