Driver's Seat Ergonomics - Unfair Takes A Seat

The Project Unfair Camaro gets closer to completion as we focus on the ergonomics of the cockpit

John Parsons Jul 18, 2011 0 Comment(s)
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Editor's Note
This month's story about the fabrication and ergonomics of our Project Unfair's pedals, seat, and steering column takes place back at II Much Fabrication in John Parsons' small shop. --Jim Campisano

With the Coast Chassis Design rollcage installed, Frank Serafine (of Prodigy Customs) and I needed to get the ergonomics of our '69 Camaro in order. Since we've moved the firewall, raised the floor, made a custom transmission tunnel, and installed a rollcage, this is no simple bolt-in deal. Getting all the controls into comfortable reach and incorporating proper safety methods is no easy matter. The relationships between the seat, steering wheel, and pedals are not that obvious and something most of us take for granted when we jump into our factory-built cars. With all the changes to the surfaces in the driver's area, we had to start our positioning of the driver's controls at the beginning.

Sucp 1108 Drivers Seat Ergonomics Unfair Takes A Seat 001 2/27

The pedal/steering wheel/seat arrangement is a bit interdependent, but you have to start somewhere. In general (with an inch or two of tolerance), the most ergonomic performance driving position has the seat back tilted at least 15 degrees, with the steering wheel centered with the seat. The best racing position has the driver's hands at the 9-and-3 position and close enough so that the either arm can be extended over the top of the steering wheel with the wrist resting on the top of the wheel without the shoulders coming away from the seat.

From there, the pedals should be positioned with the brake pedal centered under the column, and the clutch pedal between 4 and 5 inches away (measured from the centers of the pedal pads). It's often more comfortable for the clutch to be an inch or so higher than the brake. We're going to road race this car (a lot!), and that means the throttle needs to be reachable while braking for heel-toe downshifts. That will require the throttle to be within 4 inches of the brake and about midway through the brake pedal's travel. The idea is to be able to blip the throttle with the side of your foot while maintaining threshold braking with the ball of your foot. The brake and clutch pedals should be largely controlled by your legs, while the throttle is controlled by your ankle, which is why the brake and clutch pedals are closer to you than the throttle.

That's a lot of interdependent variables, without even taking driver preferences into play. The chances of getting all this right the first time are pretty slim. Frank and I are about the same height with similar body types, but we still need some adjustability in order for the two of us to be comfortable driving the car. Most factory cars take that into account with adjustable seats, but that's not an option for us since the six-point Schroth Racing harness has very specific mount points. The only solution, since the seat is fixed into place, is to make the pedals adjustable.

We'll be using Cobra Suzuka Pro seats. (The Pro means "middle-aged man" as it is 2 inches wider in the "butt-dyno" area.) The Suzuka is an FIA-approved fixed-back racing seat but uses advanced materials for driver comfort and style. It is also designed for use with a six-point harness. We chose a fixed-back seat since there is no backseat and no need to tilt the seat back forward. It's also smaller and lighter.

The pedal set comes from Wilwood (as do the master cylinders and brakes), though our unique firewall and the need for adjustable pedals means we have to modify their setup somewhat. Only Wilwood has all the various pedal sets and balance bars we needed to get adjustable pedals with perfect ergonomics and their track-proven performance. A balance-bar setup is heavily used for circle track racing because it allows different master cylinders to be used on front and rear brakes with adjustment of the relative pressures between them at each position of the brake pedal. It's a great option for use on the street for the same reason: optimum tuning of master cylinder and caliper piston diameters for each end of the car.




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