truck cap too tall / remove gap / material? [several photos]

[Andale]

As you can see my cap sticks up a bit (and off the back but that is mentioned later) and I honestly would like to raise it up and make it a bit taller. I have two ideas, (1) is to just raise it (and fill the gap, that is the next section) and (2) is to raise the rear only by cutting a wedge to make it tall at the back end and giving me a bit of downforce BUT this makes the rear window kinda weird.

Next!

I need to cut down the length of this cap as it is from a longbed S10. I was thinking about using some type of foam or rubber and was also trying to decide on whether I should put it between the existing front of the cap and back of the cab or getting a flat material that will last and fit/glue across the gap. The problem is that the cap has a solid window and my truck has a slider, which I use a lot since I don't care to use the A/C. I also need to cut so many inches off the truck that the windows make it where I have to cut front AND back and move them. I was thinking if I could find something thick I could tack to the back of the cab and push the cap's sharp edge into then that would be easiest.

[ChazInMT]

FTLOG Man, don't raise it up in back only. You may as well just put drag chutes on your bumper you'll create so much extra drag. If you wanna modify it and make it aero so it saves you money at the pump, follow the dotted lines when you cut and remount the rear window at the angle. You'll lose a bit of space but you'll have something that really saves you bucks, especially if you are on the highway.

[Andale]

I was thinking about tilting the back but it will be minimal because of the usable space

[BamZipPow]

If yer gutsy enough...I would take it apart and revamp it. Make it to the size of yer bed and be done with it.

In my aerocap thread...I used a ducktail to bridge the gap between the cap and the cab.
Another truck aero cap idea...

[jakobnev]

Originally Posted by ChazInMT

That looks like the absolutely worst angle you can have.

(There are nice graphs that show Cd as a function of rear window angle in the Hucho fanboi threads IIRC)

[KamperBob]

The good thing about aluminum caps is you can unskin, rebone and reskin 'em without much time, hassle or cost. That's how I made a gap-filler cap between truck cab and fifth wheel nose.


The bad thing about aluminum caps is the usual air snagger lip on the back. Compound curvature at the trailing edge would be ideal but with metal that could take a lot of time, hassle or cost.