Nobody really knows where the whammy tank came from, but we know that it's has been around for years. It has evolved over time, but there was never really an industrial use for them until the Lowrider market demanded it. The first crude versions for the tail-gate pumps were made from two reservoir tanks which were welded together. These usually found a reason to leak for a variety of reasons, including poor welding techniques, and blowing pin holes through the thinly stamped tanks. These pinholes sometimes occurred when the fluid was being dumped back into the reservoir, leaving the air pressure to make the tank expand. In other instances, the reservoir tank would be made too small for the two pumps that shared the fluid, which did not allow the car's cylinders to fully travel and expand to capacity.
Today's whammy tank is made from 1/8 thick round tubing stock, and is machined to hold enough oil for two suction gears, or "pump heads," as we sometimes refer to them. The individualism of styles and needs have allowed builders to create their own unique versions of whammy tanks, including see-through plexi-glass versions. The plexi-glass versions are not too common, as some of the material being used was not rated well for the job, and thus would crack under the pressure. Other modifications commonly found on whammy tanks have come in the form of custom engraving or paint, used to match the exterior of the car. Adding an oversized fill fitting or plug to a reservoir tank is a practice that has a benefit or two as well. With this, it's easier to fill the tank with oil, and you can also check the fluids a lot easier.
This month, we visited Go-Ez Customs of Anaheim, CA, and their crew showed us a quick and cheap upgrade for a custom whammy tank build. Now follow along, as the Go-Ez crew custom design a raw tank.