Expert: Paul Wilczynski - 7/22/2009

Question
QUESTION: Hello Paul.I have a 1956 Ford Fairlane and my buddy has a 55 Customline(same cars mechanically).We purchased 2 power brake conversion kits(Booster-mast cylinder and required brackets etc).He has installed his and has drum brakes all around.He has not added a proportioning valve.The brakes work well however my understanding is that a valve is needed to get the advantage of dual master cylinder.Is this correct.I am going to add disc brakes to mine prior to installing the booster kit.I know a valve is required with this combo for proper brake balance.My questio is can he and I use the same type valve or does his not require one at all.Thanks Mark

ANSWER: In an all-drum setup, a proportioning valve (its proper term) is not strictly required. However, no car has equal force required front-to-rear (due to weight imbalance), so a valve is a good idea on any system if you want to fine-tune performance and feel.

A proportioning valve is a necessity in a disc/drum custom system due to the differences in mechanical advantage in the two technologies.

In both cases, I'd use an adjustable proportioning valve. I favor Wilwoods, mounted low on the frame but easily accessible without crawling under the car. The easier it is to get to, the easier it is to dial in perfectly.

--Paul

---------- FOLLOW-UP ----------

QUESTION: Thanks Paul.The factory Ford junction/proportioning valve that was used in the 70's had the warning light wire which activated the light on the dash if pressure was lost in either the front or back brakes.I am told that it also cutoff flow to the leaking circuit so you stll had brakes with the dual master cylinder.Does the dual master still work as it should in the event of a failure without this type valve.I understand what you are suggesting with the adjustable type prop valve.Does that get plumbed into the line going to the rear brakes which is what I assume?

Answer
I think that the warning light is redundant once he brakes have been rebuilt with new parts. Beleive me, you'll know if either front or rear brakes go out, and if both fail, a warning light is useless, since it only goes on when the pedal is depressed anyway. Too late...

I'd prefer the easily adjustable type of valve. A Wilwood is better made than the factory part, anyway.

Plumb it into the rear line before the "T".

--Paul