Tech Tuesday: The torsion bar suspension is unique characteristic of Porsche of the 356 and 911s through the G-body cars of the Carrera 3.2. Porsche invented this suspension and stayed with it until the 964-generation of 911 was launched in 1988.
Ferdinand Porsche first applied for a patent on the torsion bar suspension on August 10, 1931. The typical chassis design at that point used heavy leaf springs that were a carry-over from the days of carriages. Torsion bars could be installed lengthways or crossways and were connected to the axle via the lever of a suspension arm.
The torsion bar suspension was designed to save space and weight. A torsion bar suspension at the time provided better traction on uneven roads and reduced rolling on corners. To quote the 1955 Porsche Showroom Poster featuring the Torsion Bar Suspension:
“PORSCHE's famous torsion bar suspension is unequaled in automotive history. Forget costly maintenance and compli- cated adjustments. Fast acting, positive, torsion bars give 100% wheel contact with the road at all times. The results to you are a smooth ride, unsurpassed handling ease, and greatly increa- sed safety qualities. The torsion suspension is one reason why PORSCHE is years ahead! PERFECT-YET SIMPLE”
Ferdinand Porsche used the torsion bar suspension in racing cars while the French automotive manufacturers were the first to pick up the patent and apply the design to production models. Ferry Porsche first used the design on the 356 that featured independent suspension with trailing links at the front (also a Porsche patent) with traverse torsion bar suspension.
The torsion bar design was then carried over to the new 911. To pick up the description of the Porsche 911 torsion bar suspension from Porsche itself:
“Wishbones were used to guide the front axle. Each of the longitudinal torsion bars went through the link pivot, was connected to the transverse link at the front and braced against the frame cross tube at the rear. An adjuster screw could be used to set the preload and thus adjust the ground clearance. An additional hollow rubber spring had a strong progressive effect in the last third of the suspension travel. This prevented the suspension from bottoming out in highly dynamic driving. By contrast, the rear wheels were supported by transverse torsion bars. Progressive hollow rubber springs also took effect in the last third of the wheel travel here.”
What is interesting to note is that within air-cooled Porsches, the type of suspension of the 911 has become a defining engineering characteristic that separates the lineage. With the launch of the Porsche 964 in 1988 the torsion bar suspension was replaced with a coil over suspension system that was required with the advent of the four-wheel drive system. This change in suspension moved the Porsche 911 into a new engineering advancement that changed the driving characteristics of the car. Not that it wasn’t a good engineering advancement but it left a Porsche innovation and tradition that a Porsche purist was reluctant to accept.
Sources: 70 years of Porsche Sports Cars press release, Rennlist, and Porsche: Excellence was expected.
Tags: Porsche suspension, Porsche torsion bar suspension