HI Folks: I just came away from the Towing Forum and found out that Chev and GMC Trucks have been designed to have a crown designed into their truck beds (truck bed is not flat lengthwise). Link http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28594661.cfm http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28594661.cfmI just checked my 2015 3500 GMC and it has what appears to be as much as a 1/2 crown in the middle. It is my suspicion that this crown has contributed to the popping up and down of my overcap truck camper when driving down the road (Lance 1181). The existence of this crown maybe further be supported by the fact that I have a noticeable decreasing distance toward the rear between the top of truck box rails and underside of the camper when loaded. Since the COG of my camper is marginally behind the rear axle this would exacerbate the tendency of the truck camper overcap to pop up and down while driving. Hear we are trying to reduce overcap popping by installing Lance struts attached to the hood hinges while the truck bed could be contributing to the problem. I am now running with a 1/2 inch sheet of plywood under a heavy 1/4 inch rubber mat and am contemplating gluing a 3/8 inch thick sheet of 4'x2' plywood on the rear half of the existing plywood to help level out the truck bed. Has anyone run into this yet and how have you or would you address it?

Seems to me, if you were to put a piece of plywood/strand board, 1/2" thick x 12" to 18" wide in front and to the rear of the wheel wells, with a full sheet plywood on top, it would pretty much bridge the crown. Wayne

I am so glad to hear that someone else is having this same problem as I am. I've tried everything everyone has suggested to me and I still have a porpoising problem also. The next thing I was going to try was placing a 1x6 board on the rear of the truck bed to shift it up slightly. Please let me know if your solution works.

That's pretty amazing. The engineers obviously don't think about how the trucks will be used when they design their beds. First, they changed their tail gate width and now this change. Sounds like they have too much time on their hands. Of course, it could be a manufacturing defect.In any case, for the truck camper, I'd probably ask Lance what they recommend. I wouldn't be surprised if the bottom of the camper flexed enough to "level". The beds are usually attached on top of bushings. Another thought is to change the bushings under the middle of the bed to smaller ones if that is how they are crowing it.

I think I will hang on to my 09 Chevy for a while longer. Still works great and I have a flat bed. The crown thing doesnt make any sense.

Crown Designed Into Chev and GMC Truck Beds | Good Sam Community

deltabravo
Nomad
Oct 23, 2015
kerry4951 wrote:
I think I will hang on to my 09 Chevy for a while longer. Still works great and I have a flat bed.

I'm with you. My 09 just hit 42,000 miles last week. As much as I want a new truck, I'm sure it will be a nuisance dealing with the crown in the bed.

I was following the crowned bed theory when someone was posting about their B&W Companion hitch. I looked at a 2015 truck. It appeared there was a crown in the bed, but it was hard to tell for sure because when the tailgate was down, the flat surface of the tailgate sat higher than the bed floor, so it was hard to get a good visual of the truck bed.
monkey44
Nomad II
Oct 23, 2015
I never noticed that problem, but because the rails are a bit shorter, I had to raise the camper one inch. I ran 1x6 PT decking on both ends and one in center cross-ways... I've not had a problem, and it also keeps the bottom from sitting in water when it rains. I also have a 1/2 inch rubber mat in the bed.
kerry4951
Explorer
Oct 23, 2015
deltabravo wrote:
kerry4951 wrote:
I think I will hang on to my 09 Chevy for a while longer. Still works great and I have a flat bed.

I'm with you. My 09 just hit 42,000 miles last week. As much as I want a new truck, I'm sure it will be a nuisance dealing with the crown in the bed.

I was following the crowned bed theory when someone was posting about their B&W Companion hitch. I looked at a 2015 truck. It appeared there was a crown in the bed, but it was hard to tell for sure because when the tailgate was down, the flat surface of the tailgate sat higher than the bed floor, so it was hard to get a good visual of the truck bed.

I just went over 70K and the truck is still perfect. Never had an issue with it........knock on wood.
CAJW
Explorer
Oct 23, 2015
Just measured my 2013 LWB - Bed is crowned front to back approx 3/16", measured with a 78" long level. Have been using a 5/8" thick rubber horse mat, but have experienced some porpoising that I'd like to eliminate or reduce. Will be watching this thread as to what fixes work. Thanks GM, Sheesh!
nycsteve
Explorer
Oct 23, 2015
iwon415 wrote:
Another reason to buy Ford?

Yup.
mkirsch
Nomad II
Oct 23, 2015
It should be simple to prove that the camper is rocking: Rock it! Take the turnbuckles off and give it a shove. The crown is right near the COG so any mere mortal should be able to roll the camper back and forth easily.

I find it hard to believe that a Lance 1181 is so rigidly built that it doesn't just conform to this relatively slight 1/2" crown under its own weight. It's not like it's some space-age geodesic structure built from exotic materials. It's a wood box!
Victory402
Explorer
Oct 23, 2015
Seems to me a sheet of 1" foam board would fix this.
Deb_and_Ed_M
Explorer II
Oct 23, 2015
CAJW wrote:
Just measured my 2013 LWB - Bed is crowned front to back approx 3/16", measured with a 78" long level. Have been using a 5/8" thick rubber horse mat, but have experienced some porpoising that I'd like to eliminate or reduce. Will be watching this thread as to what fixes work. Thanks GM, Sheesh!

Well, now I'm going to go take a harder look at my 2014 Ram 1500. As we drove down the highway, I was watching my camper raise and lower - I assumed it was the Brophy clamp-on tiedowns flexing the truck's bedrails, giving the camper just enough room to rock. Never dawned on me that the truck bed might be curved?
Reddog1
Explorer II
Oct 23, 2015
I have my TC raised, so I can clear 5th wheel rails and get to the truck bed under the wings. Through the years, I have raised it with 2x4s or 4x4s running side to side in front of and behind the wheel wells. I think. I usually put nothing on top, just loaded the TC. Had I a crown, it would have bridged it.
Old_Days
Explorer II
Oct 23, 2015
If you have to make up 3/16 inch you could use the 1/4 inch Styrofoam that you put under siding for a house. I just looked at my Ford and didn't see any crown in the box.