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Old 01-21-2008, 06:36 PM   #17 (permalink)
Big Dave
Master EcoModder
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Join Date: Jan 2008
Location: Steppes of Central Indiana
Posts: 1,319

The Red Baron - '00 Ford F-350 XLT
90 day: 27.99 mpg (US)

Impala Phase Zero - '96 Chevrolet Impala SS
90 day: 21.03 mpg (US)
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After chopping through this for the third time, I am psyched. My bed fairing oveshot his optimum (pure luck) and is too flat. This is easily rectified on the next try. I'll carry more of a barrel shape along the centerline to the tail gate. Not only will this approach his optimized shape but make room for more stuff to be carried along the center four feet of the bed.

Having lived with an air dam much like Capt. Williams' I have some suggestions to offer.

1. My air dam is fastened to the bumper with nine nut sets. I would suggest attaching the dam (and drilling holes) starting with the center. On the center I would put 6-10 washers between the bumper and the air dam. One the flanking two holes I subtract a couple, and continue on to zero washers. doing this will round the air dam off as viewed from above. This will tend to throw the air off more quickly to the side rather than stagnating (max pressure) right in front of the truck. another thing this avoids. My air dam like Capt. Williams' is falt to the wind and the unsupported part of it vibrates along its length like a clarinet reed. Putting a curve in the rubber dam will increase the stiffness and avoid this vibration.

2. You can start with the air dam as low as you like - I started at 3/4 inch - but the road will eventually wear it to about 1.5" clearance. Mine only dragged on braking and backing into my garage, but it wore the rubber down all the same. Once it got to 1.5 inches the rubbing stopped.

3. I used capscrews and fender washers to attach the air dam, but the fender washers do not spread the clamping load evenly and when the air dam began vibrating the fender washer cut into the rubber. I would recommend a stainless steel or aluminum clamping plate in front of the air dam to even out the clamping pressure and to make the air dam hold its desired shape better.

Next steps:
A tail cone attached to the tail gate to carry the curve on down.
Side skirts and fender skirts.
2000 Ford F-350 SC 4x2 6 Speed Manual
4" Slam
3.08:1 gears and Gear Vendor Overdrive
Rubber Conveyor Belt Air Dam
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