How An Opel Sedan Helped Develop The Porsche 928
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Porsche and Opel are two brands not often spoken in the same sentence. However, as Porsche continued development of its 928 model (which was supposed to replace the 911 at one point), engineers had a problem.
So the story goes, according to Road and Track, the 928 had an incredible tendency to oversteer and the steering often presented itself as incredibly unstable. Per the report, “lateral forces in curves cause the outer rear wheel to switch to a positive track as if a person’s foot were turned out. What’s almost even worse is that releasing the accelerator during a curve causes a frontward shift in the car’s center of gravity, which lowers the load on the rear.”
Porsche had identified the problem in the 1950s, though no solution had arisen since then. But, Wolfhelm Gorissen, Manfred Bantle and Helmut Flegl finally found an answer.
The team took a standard Opel sedan and created a simulation tool to create the undesired effects the 928 grand tourer exhibited. With two steering wheels (one in the front, and one in the rear), Bantle drove the car normally while Walter Näher created the unstable steering feel from the rear steering wheel.
During the trials, the team was able to find that even small angles could fix the unstable feelings and they developed the Weissach axle. The axle features rubber bushings between the axle components and suspension to produce more neutral handling. And it worked, thanks to an Opel development car.
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Better yet the 1988 Fiero had a suspension designed by GM engineers [Not Lotus as some contend].
To tune the car they had Porsche Engineering come in and dial in the scrub radius and other fine points to get the feel right on the steering.
GM had two Mules in 1985 that were 2.9 Turbo Coupes. One was red and one was black and they had tail lamps that lite up to say Porsche Eater. Pontiac made the engineers remove the tail lamps as in 1985 Porsche came in to work on the new 88 suspension.
This info came from the Gary Witzenburg Fiero Book and it also came from Tom Goad as related in an interview in High Performance Pontiac Magazine.
Over the years many alliances have come to light. Most recently the Turbo 2.0 Ecotec contained engineering from Lotus Engineering on oiling and block strength.
Though Lotus did have some input on the suspension tuning for the 88 Fiero no?
No Lotus had nothing to do with it and never had any input.
In fact the GM engineers were upset about this false rumor as they felt they did a hell of a job as related by Goad.
The Lotus suspension was one of many myths that surround the Fiero.
Because of the dysfunction of GM and many burned bridges and hard feelings surrounding the Fiero so much of the true story of the Fiero has never been clearly stated in one place.
A good book on this would be a great benefit to set the story straight as the Witzenburg book was a GM sponsored approved telling of the story.
The Fiero story is a real snap shot of the real dysfunction at GM and management that lead to their bankruptcy.
If GM had Chevy and Pontiac working together to make the Fiero and Corvette compliment each other vs. them fighting for the same turf GM would really had benefited.
As John Schinella once told me Chevy sold more cars so Chevy got more say, The Fiero was going to get more power at half the Vette price and they saw it as a threat. They wanted it dead and so it was killed.
Pontiac also took many risk like expecting the GM 80 program to fill the plant capacity but it was canceled and it doomed the Fiero not the fires. In fact the Fiero was far down the list on most car fires.
But the Fiero did live on in the 4th gen Firebird. Much of the styling was carried over to the new bird. It was converted to front engine and enlarged but still shared most of the styling.
Compare the 1990 Fiero GT to 4th gen F body and you will see the similarities.
Did they use the Opel Kapitan/Admiral/Diplomat with the DeDion rear suspension? Many other Opel sedans used a torque tube rear end which would not have been ideal for steering input.
It was the 911 not the 928