When building a street rod there are some decisions that seem like a good idea at the time but turn out not to be so hot when you have to live with them. A case in point is the under-the-floor master cylinder in the 1934 Chevy coupe belonging to SR's group publisher, Tim Foss.
Although a below-deck master cylinder is cool for keeping the firewall clean, things that are out of sight are often out of mind. That's another way of saying if you don't see the master cylinder the fluid level may not be checked as often as it should. And, when you do decide to take a look, gaining access is often difficult unless you're adept at standing on your head—and it's well known that Foss hates to mess up his hair.
To make life easier, Foss' coupe was delivered to the Source Interlink Media Tech Center where Jason Scudellari, our in-house installation whiz kid, would be installing an OTB Gear remote brake reservoir on the firewall. Not only does it look cool, it also makes checking and filling that vital fluid easier. While the brake system was getting a tune-up there was another issue to be addressed. The Chevy had been equipped with a 1-inch Corvette master cylinder and a 7-inch booster, a commonly used combination with four-wheel discs. However the brakes were very touchy, so it was decided to resolve that issue as well.
Master cylinder bore size is a subject that often causes confusion. Simply put, a larger master cylinder bore produces more volume and less pressure while by comparison a smaller bore produces more pressure with less volume. With the wide variety of brake components available, recommending a master cylinder without knowing specifics is impossible. According to the experts at Wilwood, to select an appropriate master cylinder the combined piston area and piston volume of the calipers along with the pedal ratio must be known. Whether the system is boosted or not is another consideration. Then to determine the appropriate master cylinder bore for any specific application, review Wilwood's Tech Tip Guide or contact a Wilwood Sales Technician at (805) 388-1188 or email sales/tech support at firstname.lastname@example.org.
While we can't give blanket recommendations, with the combination of components used in this car a 7/8-inch bore master cylinder without a booster provided excellent stopping power without the over sensitivity that existed previously. With a new Wilwood master cylinder for better brakes and an OTB remote reservoir for filling it, the Chevy's brakes are out of sight—every way.