The hydroscopic nature of brake fluid means the longer it sits in your bike's lines, the more water it sucks up and the nastier it gets. Exhumed from the back of the garage after several years of storage, the brakes on my 1974 Ducati Super Sport had become unusable. Putrefied brake fluid had destroyed the seals in the front master cylinder, damaged those in the rear, and seized two of the three calipers.
The damage was far beyond anything a rebuild would remedy. Fortunately, AP Racing, which made some of the first disc brakes for motorcycles in the 1960s, still manufactures replacement components for classic bikes.
Replacing the mishmash of original parts on the Ducati (Italian Scarab calipers in front and an English Lockheed in back) required some improvisation. The 3/8-inch mounting holes in the new pinchers required drilling to accept the Ducati's 10mm bolts. Once drilled, the attractive new components bolted up easily, with pistons that readily slid back into their bores to aid installation.
Filling and bleeding the front brake system required some creativity because the bleeders are located on the bottom of the calipers, facing the wheel hub. Removing the calipers and mounting them in a bench jig was the only way to thoroughly bleed them. Making up for this, the rear caliper cooperated perfectly, and in the end the Ducati moved from the disabled list to active-duty status for the first time in years.
AP Racing Brakes
Price: Front master cylinder $474
Rear master cylinder $420
Calipers (3) $1119
Brake pads (3 sets) $105
Contact: AP Racing
Verdict 4 stars out of 5
Not easy or inexpensive, but a deserving classic bike is now back in business.