Silver Solder Restores a Whizzer Motor Tank on a 1946 Schwinn

This 1946 antique Schwinn deluxe B6 bicycle has a loose bung on its 1947 Whizzer H steel motor tank, a common issue found during vintage motorized bicycle restorations. To properly secure the bung without damaging the thin steel tank, Denis’s Restoration Garage selected silver solder as the ideal repair method. Using an oxyacetylene torch and Muggy Weld SSF-6 56% Silver Solder, the bung was carefully brazed back onto the Whizzer motor tank body. Silver solder was chosen for its lower working temperature, excellent flow characteristics, and ability to create a strong, leak-free bond without warping the parent metal. Once the brazing process was complete, a wire brush was used to clean the repair area, and the bung was then tapped and threaded to restore full functionality.

Whizzer motor tanks gained popularity during WWII as an economical solution to gas shortages, allowing riders to convert standard bicycles into efficient motorized transportation. Today, many of these restored antique motorized bicycles sell for thousands of dollars at auction, making proper repair techniques critical. Period advertisements captured the appeal perfectly, proclaiming, “Ride one and you’ll buy one.” They went on to list the advantages of the Whizzer: “(It) will take you where the fish are waiting. A woods trail is as good as a highway for this sturdy 2-1/2 hp motor. The economical, comfortable way to ride to work. 125 or more miles per gallon of gas. And no parking problems to worry about.”

Successful silver solder repairs begin with thorough surface preparation. Prior to brazing, the parent metal must be completely cleaned using a wire brush or sandpaper to remove oxidation, residue, and contaminants. Proper pre-cleaning allows the silver solder to flow smoothly and bond evenly across the joint. During heating, the torch must be moved consistently to distribute heat evenly and prevent overheating the thin motor tank steel, which could lead to distortion or weakened metal.

Note: The paint-related heat damage visible in this restoration could have been minimized or eliminated by applying Heat Freeze Heat Paste around the repair area before brazing the Whizzer motor tank. Heat control products are especially valuable when working on painted or historically significant components.

After the silver solder brazing process was complete, the bung was tapped and threaded, and the tank was sealed, flushed, filled and thoroughly inspected. The repair passed inspection with zero leaks reported, preserving both the function and historical value of this rare Whizzer Motor Tank. Thanks, Denis, for sharing this informative video.

Thanks, Tracy, for sharing this informative video featuring a Whizzer tank repair with SSF-6 Silver Solder. Be sure to subscribe to C10Trace YouTube channel for more videos.

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Updated 1/12/26