Installation of the Langness Spoiler
Here's the installation of the spoiler that David Langness developed. I chose this one because it's the only one that I have found that actually claims to produce real downforce; all others are cosmetic only. With a couple of minor exceptions, my mods offer either performance gains or advantages in utility. I don't go for flash.
Here is some of the masking I did getting ready to remove the stock spoiler. I should have read the Factory Service Manual before removal, it gives a method that won't harm the paint underneath it (cut through the double sided tape with 60# monofilament fishing line.) I left a couple of small scratches with my sharp putty knife, but nothing serious. The knife you see in the photo was worthless for removal.
This is what it looks like without the spoiler.
This and the following two shots were taken while I was fitting the spoiler to my deck lid. David designed it using three different Impalas and each was different from the others. So each spoiler will need to be fitted to an individual vehicle. I noticed that the stock one didn't fit exactly right, the tape on the right end wasn't stuck to the deck lid.
I needed to enlarge the bolt holes to move the new spoiler about 1/16" to the right and about 1/8" forward. I used a Dremel-type tool with a diamond burr. I also used that tool to grind down the epoxy and fiberglass holding the mounting bolts so it would sit down flat. A very little file work was necessary on the tape surfaces to finish the fit.
Here is the end where it overlaps the rear quarter. This makes it very easy to get the spoiler centered. During autocrossing, the body didn't rack enough to make the tips touch the quarters.
The finished product. My body shop was impressed with the quality of the glass work. Only one pinhole in the gelcoat and the piece didn't require much blocking to look good. Yes, I know the car is filthy. The Corps of Engineers is hauling dredge spoils on the only road into work and it was raining the morning the photos were taken.
You can see the gap between the spoiler and the body in this shot.
This side view shows the angle of the blade well. It's deflecting the air up well enough that I'm picking up much more dirt on the rear of the car. But I don't care, it'll help keep the rear end stuck down at 140+ mph (yes, I've driven it that fast.)