How minimal of clearance is okay between cab and cabover?

Thanks Wayne for the info
I've been wanting to raise mine a couple of inches to store our Champion genny under the rear overhang on a carryall.

On my current truck and TC, I have had from two inches to to about eight inches clearance, depending of how I raised it. I now have about 6 inches clearance. By the seat of my pants and hand calculations, I can tell no difference in how my setup handles on the road or change in MPG on the fuel.

The only obvious difference is I can I can reach over the sides of the truck bed with the TC loaded to take advantage of the storage. It is much easier to wash the top of the truck cab, and the front of the TC behind the cab.

I tried the dense foam, but did not like it. The normal rocking of the TC side to side beat down the foam at the edges of the TC. Not a major problem, but it also was an issue to store when I unloaded the TC. I tried several methods to raise the TC. I prefer to use 2x4's or 4x4's side to side in the bed of the truck. Kiln dried prefered simply because the pieces are lighter, easier to load.

Wayne

Here's two and 1/4 inches clearance
We've been plenty rough with the rig and no contact yet.

This is from Lance
1 1/2" for cabover
1/2" for bed rails
hope this helps :)

Yeah, one good bump and you're going to end up with one big dent in your truck's roof.

Do NOT put anything in between the camper and roof. That will just cause a bigger dent. The sheet metal on modern trucks is paper thin and crumples with little to no effort.

I had too little clearance--now I have a damaged truck roof-----added 2" polystyrene---proved to be working just fine
Nigel & Pamala--UK

I'd space it up for more clearance.

You want to close the gap, stick in a swim noodle. Notch it in the middle and bend it into a V shape. You can add on to each leg of the V with another noodle, just stick a PVC pipe inside them.

Depends on the amount of flex in the rubber bed-frame mounts .
I'd add a sheet of ridged 3/4 or 1 inch foam insulation as a spacer
A smaller gap will help but so little you would never be able to measure it.