Drum brakes get a bad rap because they aren’t very effective when compared to rim brakes. But, on vintage tandems, drum brakes are added to assist with rim braking. My 1977 Jack Taylor tandem features this front brake augmentation, which helps to keep the heavier and more powerful tandem bike’s front rim from overheating on descents. An overheated rim can blow off a tire – not a good thing!
To accomplish this dual braking, the Mafac lever is modified to accept two cables – one for the cantilevers, and one for the drum brakes.
This bike’s drum brake hub is a cup and cone Maxi Car model featuring black dust caps. The drum and pads were filthy dirty, and one pad had separated from the brake arms. The pads were covered in grime and were glazed, but did have more than 2mm of depth meaning that they were still usable.
I cleaned and sanded the drum and the pads to smooth out the contact surface and remove the glazing. I also re-glued the separated pad to its arm, using an epoxy resin rated for extreme high heat (a JB weld product). I clamped that with a C clamp and let it sit for about a week. Then, it was time for reassembly. Fortunately, when I disassembled the hub I took a series of photos at each stage. I referred to this series of photos while I put the drum brake hub back together.
But, I also consulted Glenn’s Complete Bicycle Manual for an overview of the process. This manual is the only vintage repair manual that addresses the overhaul of drum brakes in adequate detail. Above are a few pages which illustrate the process. In total, the manual contains 5 full pages dedicated to drum brake overhauls. There are locknuts, spacers and nuts which need to be in the right place in order for the brake to operate as intended, which is why it’s so important to document the disassembly process.
This model of drum brake features only one spring, whereas some contain two springs. When the arm is engaged, the spring opens and moves the pads outward toward the drum via a cam mechanism.
Once the hub was reassembled I put the wheel up into the dropouts and attached the fixed arm to the fork blade, using the original “88” rated bolt. This designation signifies its tensile strength.
Having reinstalled the fork and headset, it was now time to install the stem so that I could set up the bars and brake levers. I had noticed when working on the fork adjustment that there was no hanger for the cantilevers, and that’s when I remembered that this bike has a cable stop drilled on the stem. I ended up having to gently re-tap the threads for the barrel adjuster, but the Milremo stem cleaned up beautifully after polishing it with Nevr Dull.
The next step was to set up the cable, and for that I needed to make sure I understood how the hardware should be positioned into the brake arm.
The original hardware’s end cap could not be reused because the cable would not come out, so I found a replacement and began the process of setting up cable tension. It took several trial and error passes to get the cable tension correct so that the pads did not contact the drum when not engaged, but contacted the drum adequately when engaged without bottoming out the brake lever.
I made this short video showing the operation of the brake. All looks good, and now it’s time to move on to the installation of the cantilevers. After that, I’ll continue on to the drive train, having previously cleaned, polished, and waxed the frame. I’m glad to be making progress on this wonderful vintage machine.
