The "Brick" gets a new air dam

[JasonG]

A heat gun would probably work on vinyl. I wanted soft curves so I didn't use one.
It followed the front and sides easily. To get the sharper radius where the bumper turns you typically have to notch an "L" shape.


While trucks may come from the factory with 7"+ clearance, I haven't scraped any driveways yet. I also live on a gravel road, no issues there.
The only thing that this
Has rubbed is on a tall curb in a parking lot.

[JasonG]

Just filled up and am sort of happy.

15.1 MPG. This tank had a lot of traffic in it though.
Normally tanks like this are in the mid to high thirteens.

Well, I'm in a gas station and need to get back to work.

[kach22i]

You are 1-1/4" lower than me now.

I better get to work on phase II of my chin spoiler.

[JasonG]

Just filled up, 15.28

Found out last night I need to modify my design.
On the way home my buddy says " hey, that thingie on your van is bent"
Turns out around 65MPH, it starts to bend back and by 70MPH the right side has fully flagged back in the wind.

I think a horizontal brace 2/3 way down with 2 kickers to ___________ are next.
That way there will still be some give at the bottom.

Anybody else have this issue ? The truck with the conveyerbelt dam (Dave?) ?
Darin, did you have this issue with yours ?

[nemo]

That is a very interesting question. This could be one reason why some are not getting the expected results. I don't believe my air dam extension is bending back. My air dam is added on to an existing one. It is 1/2 inch shorter than the first picture so it is about 1/4 inch below the sub frame.





But now I need to find a way to be sure.

[JasonG]

At around 2" of extension you should be fine.
This one hangs down 8" and is made from a single layer of vinyl.
Coroplast would've been stiffer but caused a mounting issue.
Hope to get to this later today.

[euromodder]

Originally Posted by JasonG

Found out last night I need to modify my design.
On the way home my buddy says " hey, that thingie on your van is bent"
Turns out around 65MPH, it starts to bend back and by 70MPH the right side has fully flagged back in the wind.

Can you curve it more ?

If there's a fair curve in the dam, it won't bend over.
You can try it with a piece of paper

[kach22i]

An aluminum splitter at the bottom will help the aero and add the strength you fear you may be missing. I don't think standard metal drip edge will be up to the task, you may have to fabricate something from scratch.

[JasonG]

I was planning on using 18ga 2"X2" angle but had trouble locating any.
Instead we used a scrap piece of 3/4" EMT conduit.
Good thing too, the bumper is a continuous radius that would've been very difficult to bend with the angle.
After installing it we found no kickers were needed as it was very stiff from the curve ( as Euromodder said )
Once again pictures had to wait until dark.

[Otto]

Some of the garden edging plastic thingies used for air dams have an extruded hollow tube along one edge: If the hollow edge is to be used at the bottom of the air dam, simply insert an aluminum tube or length of electric conduit pipe of correct diameter into the hollow edge as a stiffener. Bend the tube to the arch or curve you want for the air dam, and the arch will resist buckling from wind pressure.