by Jacin Barnes
I have a few thoughts on the dual vs. single cylinder brake system. First of all NSRA recommends dual master cylinders for several reasons. One is the multitude of failures that must occur for a total loss of brakes. In the single piston design - one failure equals trouble. Most "car guys" pay attention to the brakes that prevent failures under either system,and your points are well taken. I would suggest that you totally reconsider your upgrade from your single to the dual - as you say "not because it's politically correct" but because you can't find parts.
Sounds like a reversal on my part. Not really.....I would suggest you take the GM style dual cylinder and toss it into the trash can where it belongs. With your familiarity with older GM trucks you may remember a "Dual Bore" master cylinder that was used on the '61 era trucks with the hydraulic clutch. Real neat design that with some additional effort would make a killer lowbuck brake setup that would rival the Indy cars.
Are you still with me? I hope so. The dual bore cylinder I spoke of was originally set up with a single reservoir that was divided on the bottom to isolate each hydraulic system. This "side by side" get up allows you to connect each piston via a pivoting bar. This brake design is referred to as "balance bar". The idea is quite simple. Push on the center of the bar to achieve a 50/50 brake bias. Push 3/4 over from one side and get a 25/75 brake bias. Design the pivot to slide on a bearing and you could adjust the bias indefinitely -just like the Indy cars do. They can make adjustments on the fly for situations like rain which changes the bias requirements altogether.
There are a number of aftermarket companies who will sell the whole get up but it's on the expensive side. The GM dual bore system will allow you to make your own low buck version. The only considerations you must take into mind are bore size vs caliper (or wheel cylinder) requirements and also a stop of some sort to limit travel (pivoting) in the event of a line failure. This system will allow a true independent system giving you the security you thought you had with the new style GM cylinders.
Now the big bonus. Show me a single Hot Rod or whatever that has a truly optimized brake system. They all guess - even the big kit car companies. It's all monkey see monkey do. And let me tell you from experience the aftermarket brake bias adjusters that you screw into your brake line (basically a pressure regulator of sorts) may look good in theory , but the aren't worth a crap. They may be fine for fine tuning but certainly not for any serious brake adjustments that you need to make when building a Hot Rod. This system will allow you to truly build a great brake system - that's why the fastest cars in the world run them.
I've got one on my '34 Plymouth and it stops better than anything else I drive. Give it some thought and let me know if you agree or if you think I'm full of it!