What is the minimum clearance I need between the truck cab and camper overhang?

[Sterling1]

I'm getting a 2024 Ram 3500 DRW long bed crew cab truck for my 2000 Bigfoot 10.6 truck camper.  My measurements show I'll have about 1.5" clearance between the truck cab and camper overhang at about the center of the cab.  I'll have about 1/2" at the shark fin antenna but I plan on relocating that.  I'll have a better idea of the clearances when I get the truck.  

What is the minimum clearance I'd need at the center of the cab and at the very front of the cab to accommodate frame flexing?  

Thanks for any input

[Bedlam]

New campers have 48" between the floor base and underside of the cabover. This is a safe height to use as a reference against yours.

[user113]

In addition to the static clearance and frame flex, don't forget to also consider the movement that your tie-down system will permit.  You might even want to test this and see what happens in a panic stop situation.  I'm thinking you could use a piece of something like the crunchy FloraCraft FloraFom from Michaels.  Tape a small piece to the top of your truck and drive around.  If the cabover touches the foam it should leave some sort of witness mark from which you can better evaluate your dynamic clearance.

[srschang]

So did your camper fit with enough clearance to the cab?

[Sterling1]

I'm still waiting for the truck, the scheduled delivery date to the dealer slipped from November 11 to November 19.  Depending on how things work out I may not get it until the beginning of December.  

I contacted Bigfoot to get their input on the minimum cab clearance I would need.  I couldn't get a firm answer that they hinted 1 1/2" should be enough.  I was picturing the problem as the frame acting like a hinge between the cab and bed but they seemed more concerned about twisting and contacting towards the outside of the cab.  

[StirCrazy]

I would be concerned with only 1.5", personaly I would shoot for 3'' as a minimum but thats just me.  I have watched the camper rock going down a wavy highway.  

[Sterling1]

If I have to raise it then I'll probably shoot for more than 1 1/2".  If I can get 1 1/2" clearance without raising the camper then I'll probably give it a try.  My current truck has 2 1/8" at the minimum clearance point and it has been that way for two decades without problems, and I don't expect the new RAM to have more frame flex than my 24 year old K3500.  

[Sterling1]

Nice rig.  How much clearance do you have between the cab and camper?  

[Camper_Jeff___K]

I built a 1" insulated lift for my TC thatworked fine for several years but it only provided 1/4" cab clearance. I recently built a 1-1/2" insulated lift which gives 3/4" lift. It has never caused an issue. I may have posted a spammy video here about it last year. The new lift also helps center and keep straight in the bed, how the TC sits.

[Grit_dog]

I’d say not may have the “exact answer”. 
1.5” seems a bit light, but may work. Probably fine under normal conditions but hitting a big dip or frost heave at highway speeds might test that theory. I’d shoot for a bit more. Nothing a sheet of plywood or 1” foam under the bed mat won’t cure. 

congrats on the new rig!

[Oregun]

I agree with your assessment would feel better with at least 2" of clearance.  Another thing that might help if they are still available was shock absorbers between the camper and the truck.  I think Lance had these.  On mine I use a half inch plywood which has 1/4 inch dense carpet attached to it.

[Sterling1]

It seems like if it did slightly contact at the center of the cab roof that it wouldn't cause any permanent damage but would give me a warning that I need to do something about it.  It also depends on how the cab and camper move in relation to each other.  I.e., if it was a straight pivot at the cab to bed interface then 1 1/2" at the center of the cab would equate to about 3" required at the windshield.  I need to figure out if I can modify the shark fin antenna but keep it on the cab roof or completely move it somewhere else.  

[stevenal]

Also check the distance above the rails. My 'foot dealer had to run and get a foam sheet to get me home when it appeared the camper would hit the rails. I now have a 2X6 built platform that keeps my camper centered also.

[Sterling1]

My camper is 21" from the bottom to the part that overhangs the bed rails.  The Ram 3500 bed rail height is about 20.2"  

[MORSNOW]

There is a lot more movement up there than many realize with truck frame flex and cab over bounce.  I'd want at least 3" clearance, which would be easy for you to do with a flat frame built with 2x4 or 2x6 lumber or a sheet of pink/blue insulation board for support