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

[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

[Sterling1]

I've sen 3" mentioned before.  I've also seen some comments that some Fords had more frame flex than other trucks.  My current truck (2000 K3500 crew cab long bed) has 2 1/8" between the center of the cab and the bottom of the camper overhang and hasn't hit in 20 years.  But I only use a 1/4" thick rubber mat in the bed which minimizes the amount of camper bounce.  

Truck manufacturers brag about how strong their frames are on new trucks, I just wonder if that translates into less flex between the bed and cab.  I'd prefer to keep my center of gravity as low as possible and minimize the amount I have to raise the camper.  

[StirCrazy]

I have about 4, i could get away with and feel comfterable with 3. 

frame flex doesn't mean it is weak, a fram that will flex in most cases will usaly be stronger to a point as it is able to adsorbe slight movment where as a ridgid fram can't and will be work stressed and eventual fail.  now we will probably never see thins in our picks ups but just wanted to put that out there. 

the major issue you are going to see is if the brand crowns the bed for weight handling, this will let the camper rock back and forth more which lets the cabover get closer and farther away from the cab roof when hitting bumps and even accelerating and braking.  some people have made up for this by shimming a bed suport up to make a flat surface for the camper to sit on but then your defeating the purpose of the crown, so I am not sure what the answer is in this case, maybe some one with a crowned truck can chime in on this one, but it is a good idea to get a knowen strait edge the length of you bod and see if the bed is crowned or not then you know.