One of the main causes of poor braking are old flex hoses that have deteriorated to the point of preventing fluid from flowing freely
By Mark Macy
Shown here are two flexible brake hoses that have been sliced open. Any time you see hoses with this herringbone pattern outer covering, you can safely bet that they are very old.
Old is generally bad for rubber components, and even more so when it involves brakes and their implications for safety. While obvious damage like visible external cracks will alert you to a hose which requires replacement, it is the hidden internal damage from years of corrosive brake fluid that you should ne most concerned about.
Compare the well-used hose at the top left of this photo to the new-old-stock hose on the right. You can see that the fluid passage in the new hose is quite small compared to the outer diameter of the hose; it’s similar to the I.D. of the 3/16-inch steel lines that carry most of the brake fluid. The well-used upper hose however, has disintegrated inside and closed off almost completely, blocking fluid travel for both the application and release of brake pressure.
In most cases, pressure from the brake pedal and master cylinder will push through the restriction and apply the brakes, but the trouble starts when you take your foot off the brake pedal and the fluid cannot freely return and immediately release 100% of the pressure. Dragging or stuck brakes are the result, and we’ve seen the same thing happen to flexible clutch hoses, keeping the clutch from smoothly engaging when you let the pedal up.
Bottom line is that if you have herringbone-covered hoses, change them now. And if you are using corrosive DOT-3 or DOR-4 brake fluid, plan on changing these hoses on a regular and frequent schedule.
Editor’s note: Macy’s Garage, located in Tipp City, Ohio, specializes in the restoration of Triumph TR sports cars and the rebuilding of TR engines, gearboxes, differentials and steering boxes. For more details, go to: http://www.macysgarage.com