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

Christl
Explorer
Oct 22, 2015
Reddog1 wrote:
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

Hi Wayne: I like your idea of putting the narrow piece under the 4x8 plywood sheet as the full sheet will tend to bridge from there to the top of the crown and will end up providing the greatest amount of flat surface. I will check if as it may need to be as much as 18" wide to preform properly. cheers christl
Christl
Explorer
Oct 22, 2015
Jim&Carolyn wrote:
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.

Hi Jim and Carolyn: I will let everyone know how it works out when I put a 12"X 48" piece of 1/2 inch plywood glued under the 4'x8'x1/2" sheet right across at the rear. My response on how it dampens the porpoising will have to wait until spring as my camper is on blocks and winterized. If anyone tries it before me, I sure would like to hear about it.
JoeChiOhki
Explorer II
Oct 22, 2015
ol' grouch wrote:
Super_Dave wrote:
kerry4951 wrote:
The crown thing doesnt make any sense.

I'm going to take a stab and say that I bet it is a structural "improvement". A pre-flexed or crowned bed is stronger than a flat bed.

Sort of. Actually, most trucks are used as cars with a box on the back. The crown is to let water run out faster since most people don't carry anything. If you actually USE your truck as a truck, tough.

Aye, that's why we have half-tons, for ego compensation :p. Actual pickups start with a 2 at the beginning of their model and go up from there :p.
ol__grouch
Explorer
Oct 22, 2015
Super_Dave wrote:
kerry4951 wrote:
The crown thing doesnt make any sense.

I'm going to take a stab and say that I bet it is a structural "improvement". A pre-flexed or crowned bed is stronger than a flat bed.

Sort of. Actually, most trucks are used as cars with a box on the back. The crown is to let water run out faster since most people don't carry anything. If you actually USE your truck as a truck, tough.
Super_Dave
Explorer
Oct 22, 2015
kerry4951 wrote:
The crown thing doesnt make any sense.

I'm going to take a stab and say that I bet it is a structural "improvement". A pre-flexed or crowned bed is stronger than a flat bed.
kerry4951
Explorer
Oct 22, 2015
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.
jimh406
Explorer III
Oct 22, 2015
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.
iwon415
Explorer
Oct 22, 2015
Another reason to buy Ford?
Jim_Carolyn
Explorer
Oct 22, 2015
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.
Reddog1
Explorer II
Oct 22, 2015
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

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