Although street rods are often an expression of the owner/builder's individuality, the fact is many are based on a similar formula when it comes to the chassis. Take the '34 Ford roadster shown here as an example. It's based on a stock frame with a Total Cost Involved independent suspension up front. In the rear are standard issue components, one Currie 9-inch with Ford Explorer disc brakes, two coilovers, and four-bars. If not revolutionary, it's certainly a tried and true combination.
Normally with the previously described rear suspension arrangement there would be one more piece of linkage. While four-bars locate the rearend housing fore and aft, unless the triangulated style is used, they do nothing to control side-to-side movement. In most cases, a device called a Panhard bar connects to the chassis on one end and the axlehousing on the other. Simple and effective, a Panhard bar keeps the chassis centered over the rearend-sort of. The sort of comes from the fact that, as the suspension compresses and rebounds, the end of the Panhard bar moves in a slight arc, which means the back of the car has a minor wiggle as it works up and down. In most cases, the small amount of movement isn't objectionable, but there is a way to eliminate it completely with something called a Watt's linkage.
A Watt's linkage uses a rocker attached to the axlehousing with a pair of bars, one that attaches to each framerail. As the axlehousing moves up and down, the rocker pivots to compensate for the arc the bars travel in. The end result is the rearend stays centered as it moves up and down.
A Watt's linkage is relatively easy to build: a pair of urethane bushed links, a rocker, and some brackets and you're in business. There are also several aftermarket companies building Watt's linkage kits for performance cars, notably 5.0 Mustangs, which could be adapted. Then there's the example shown here; it came off an Australian Falcon. During a trip Down Under, we spotted one in use on a chassis being built by Larry O'Toole (editor/publisher of Australian Street Rodder). We picked up a pair at an Aussie wrecking yard for $30, and while it did take some explanation to the customs inspectors, they came home in our luggage.
To bring our '34 to a stop, we opted for Explorer disc brakes on a Currie 9-inch. Affordable and effective, the Explorer package is an option on Currie rearends. We like these brakes for a number of reasons, chief among them is the fact that they use all OEM parts, which means rebuild kits, pads, rotors, and so on are readily available at most parts houses and dealerships. The built-in parking brakes are a plus, and these brakes practically bolt on. The key word is practically.