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The Iron Duke Resource Site


 

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Welcome to my newly redesigned Fiero 2M4 resource site.  The original site recorded over 12000 visits,  hopefully this one will also prove as useful.
Ira Crummey

The Factory Setup:

1984-87 Suspension set up:

Automobile manufacturers, especially GM which got burned badly by Ralph Nader over the early Corvairís handling, are very litigation conscious. Understeer is a benign handling characteristic which can keep even the most inexperienced driver from getting into too much trouble, as a result most manufacturers build in a level of understeer to suit this goal. Mid engine cars, with the quick reflexes afforded by a low polar moment of inertia, are especially tricky since they often display a condition called trailing throttle oversteer. This means that if you suddenly come off the throttle or get on the brake while cornering the car may go into an oversteer condition which could lead to a spin. Early Porsche 911 Turbos were known for dumping more than one overzealous, under skilled driver backwards into the weeds due to this condition.

Ferrari, in the Dino 308GT4 of the 1970s, reasoned that, since most of their owners had more money than driving experience, they would build in plenty of understeer to protect their well heeled clientele from themselves. One automotive writer commented theat the rear sway bar of the 308GT4 was merely there to fill out the specification sheet and served no discernable purpose. Pontiac took the same approach with the original suspension of the Fiero. Despite a mid engine design and slightly rearward weight balance the Fiero understeers resolutely. GM reached this balance by installing only a front anti-roll bar, thus putting a greater share of the cornering forces on the front tires, causing them to slip more than the rear which leads to understeer. No one can describe the Fiero, or the Dino GT4, as poorly handling cars, but they do understeer heavily.

Other problems with the factory Fiero setup include:

A fairly large amount of steering kickback caused by a large scrub radius in the front suspension. This problem is reduced by the use of a steering damper, a shock absorber which absorbs sudden forces in the steering rack.

Bump steer in the rear suspension caused by the mounting points of the toe links in the rear suspension. (Click here to go to the article on bump steer)

Ira Crummey