[DeTomaso] DeTomaso Digest, Vol 93, Issue 4- Brake master

[JDeRyke at aol.com]

Remember with a Mustang or other cars with disc fronts & drum rears to use 
SOME sort of proportioning valve, as running the same hydraulic pressure to 
drums as to discs will usually lock the drums first, due to their 
self-energizing effect. And because of the relatively long hydraulic strokes with 
drums, a stronger keep-alive valve is needed in the drum circuit. This is 
'60s-tech some of the new guys might not have ever heard of. 
The Byars conversion master cylinders have a disc-brake keep-alive valve 
built into the MC that may not be optimum for drums. It's a thick rubber 
washer with a spring-loaded ball bearing under the reservoir attachment. 
Keep-alive valves should never be doubled so don't add an aftermarket valve on top 
of the one already there. In 4-disc Panteras with a Byars conversion MC, I 
remove it entirely, but that's just a personal preference- YMMV- J Deryke