The Weissach axle (pronounced 'Vise-' as in 'advise' and '-ach' with guttural 'ch') is a rear suspension arrangement first used in the
Porsche 928 (1978) and echoed in subsequent production models. The fully developed version was used in a
Porsche 993 (911) in 1994. The goal of the Weissach axle was to eliminate
lift-off oversteer
Lift-off oversteer (also known as snap-oversteer, trailing-throttle oversteer, throttle off oversteer, or lift-throttle oversteer) is a form of oversteer in automobiles that occurs while cornering when closing the throttle causes a deceleration, ...
by allowing the rear suspension to adjust itself during cornering manoeuvres and handle both longitudinal and lateral forces.
Name
It is named after the town of
Weissach
Weissach is a municipality in the district of Böblingen in Baden-Württemberg in Germany.
The Weissach axle is named after the town, where the research centre of Porsche is located. The Porsche 918 Spyder supercar was developed in Weissach; Por ...
, where the axle was developed at the
Porsche
Dr. Ing. h.c. F. Porsche AG, usually shortened to Porsche (; see #Pronunciation, below), is a German automobile manufacturer specializing in high-performance sports cars, SUVs and sedans, headquartered in Stuttgart, Baden-Württemberg, Germany ...
research centre.
[http://content3.eu.porsche.com/prod/company/history.nsf/deugerman/milestonesthe_seventies, (Retrieved Oct. 20. 2007)] Weissach is also a
backronym
A backronym is an acronym formed from an already existing word by expanding its letters into the words of a phrase. Backronyms may be invented with either serious or humorous intent, or they may be a type of false etymology or folk etymology. The ...
for ''Winkel einstellende, selbst stabilisierende Ausgleichs-Charakteristik'' (angle-adjusting, self-stabilizing equalization characteristic)
[Christophorus, 2018, ''Porsche 928 chassis technology - Weissach axle](_blank)
/ref>
Description
The Weissach axle is a variant of the semi-trailing arm
A (semi) trailing-arm suspension, sometimes referred to as (semi) trailing-link is a vehicle axle or wheel suspension design in which one or more horizontal arms (or "links"), perpendicular to and forward of the axle, are connecting the axle or w ...
suspension. The tendency of a vehicle to oversteer
Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occ ...
when decelerating is compounded by the compliant bushings found in most trailing arm suspensions. When the vehicle is decelerating, the trailing arm pivots towards the rear as the wheel is "pulled" backwards relative to the chassis. This results in toe out
In automotive engineering, toe, also known as tracking, is the symmetric angle that each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects. This can be contrasted with ...
, which makes the vehicle unstable.
For the Weissach axle, the front pivot bushing of the trailing arm is replaced by a short link. In this arrangement, when the vehicle decelerates and the wheel is "pulled" back, the result is toe in
In automotive engineering, toe, also known as tracking, is the symmetric angle that each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects. This can be contrasted with ...
. This adds to stability and thus, reduces oversteer
Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occ ...
.
Other manufacturers
The rear suspension of the second generation Mazda RX-7
The Mazda RX-7 is a front-engine, rear-wheel-drive, rotary engine-powered sports car that was manufactured and marketed by Mazda from 1978 until 2002 across three generations, all of which made use of a compact, lightweight Wankel rotary engine.
...
the extra link is not used, a special bushing is used in the same position in the lower control arm to perform a similar function.
References
External links
UK Car
- Weissach axle description and diagram.
Picture
{{DEFAULTSORT:Weissach Axle
Automotive suspension technologies