Original text by James Sly
Amendments and additional notes by Jan Andersson (in brown)

Keep On Swingin'

The Beetle used a simple, swing axle rear suspension from the time of it's creation in the 1930s right up to about 1968, when it was upgraded to a fully independent rear suspension (IRS). The IRS was first used on AutoStick cars and then on all models -well almost all. Actually, the Beetles that continue to roll off the assembly line in Mexico still use that venerable swing axle suspension to this day. Actually, most of the European models never got the IRS, they were all equipped with the swing axle, the only exception being the Super Beetle. Now there's no reason to think the Beetles' suspension is a bad design; Dr. Porsche used essentially the same design throughout the 1930s on the awesome 600-horsepower Auto Union Grand Prix cars as did the competition, the Mercedes Silver Arrows. And of course, up until 1966 every Porsche used virtually the same trailing arm front, swing axle rear design, including all 356s and Spiders that ran and often won their classes on the track along with more than a few prestigious victories at Le Mans. There are a lot of good things about the swing axle: It's durable - just ask early Baja runners - it's inexpensive to build, and is definitely cheap to maintain. There are no costly CV joints, and no regular repacking or service. All in all, it's a winner. The black spot on it's reputation? Handling. It seems unlikely a suspension that won at Le Mans could be faulted for bad handling, but in fact the swing axle's weak spots are twofold: huge camber changes as the wheels move up and down, and a phenomenon called "jacking." These two features combine to create a car that behaves up to the limit -and then lets go with a wicked oversteer. When you jack up your Beetle, you can see the rear wheels angle in at the bottom as the suspension drops. This top-out, bottom-in attitude is called positive camber, and it's not a good thing. When the Beetle rolls in a corner and the inside of the car lifts, the rear wheel cambers in and jacks the car up even further. The results can be rather humpty-dumpty, with the car resting on it's roof rather than its wheels. Racers decambered their Porsche rear suspension, adjusting the suspensions so the top of the tires angled in. Then, under braking or body roll as the wheels move up they go to correct camber, not to excessive. Still, in an emergency maneuver jacking can occur, so limit straps were one early, if somewhat brute force, solution.