Hi thought I read somewhere that there is a crown in an 8 ft box on the new chev;s and GmcReason I am asking is because my new northern-lite seems to really bob up and down when driving. Anyone help me with this, whats the solution. Thanks

I checked my 2012 6-1/2' box with a long level this spring, there is definitely a crown in the middle of the box, so I'd say all 2011 and newer GM's have this crown in them. I could not see the crown, but the level does not lie. I put two semi truck mudflaps under the back half of my rubber bed mat and my camper now stays level. I noticed looking at photos from past years and I can see that at times my camper looked tilted to the rear, other times level, so I raised the rear bed mat to stay level.Heck you can see it in the picture in my signature block. Here is a larger copy of the same picture (sorry it wasn't straight on from the side). Look at the camper line and the truck box and see the taper to the rear. The cabover looks leaned back also, but the truck roof slope may make it look worse than it is.

Older threads suggest that the crown exists, but I think a horse stall matt from Tractor Supply or similar should take care of it.

I have a bed mat in my truck bed and then I added a 12" deep X the width of the bed 1/2" thick rubber piece in the back of the truck bed to help compensate for the crown.

jimh425 wrote:Older threads suggest that the crown exists, but I think a horse stall matt from Tractor Supply or similar should take care of it.Maybe for some, but in my case no. I've had Tractor Supply horse mats from day one, but had some slight rocking/ porposing on certain sections of road. I had to add rubber strips 3/16" thick, 12" x 48" front and rear to help compensate for the crowned area. Rides possibly a tad bit better (less porposing) , but sometimes wishful thinking influences percieved results. At the very least, it sits level.

I've been over this issue of the crowned bed and the porpoising effect and fighting it for the past year. I've got all that stuff on my truck, air bags, stableloads, new bilstein shocks, front timbrens, rubber pad, and pads to level the bed. Maybe it's better, but I still have problems on rough roads - especially concrete. I've decided that the camper is just too heavy for the truck - and it's a 1 ton truck.

is there a crown in the 8 ft box on 16 gmc | Good Sam Community

CAJW
Explorer
Jul 16, 2016
My 2013 LWB bed crown measured 3/16" with a 6' level, if that helps you.
MORSNOW
Navigator III
Jul 16, 2016
diver57 wrote:
any idea how much the crown would be .
I think i will try the cut away idea
thanks

Get a 4' level or longer and lay it on the floor of your box and you'll see how much of a crown there is. I was surprised at how much it was on my 6-1/2' box even though I couldn't see it just by looking at it. I didn't measure it but I'm sure it's a good 1/4".
diver57
Explorer
Jul 16, 2016
any idea how much the crown would be .
I think i will try the cut away idea
thanks
SoCalDesertRid1
Explorer
Jul 16, 2016
Bob B wrote:
Use the tractor supply horse mat and cut away the center and just leave around the perimeter.......That's what I just did to mine.
Now that right there, sounds like a great idea. :)
Bob__B
Explorer
Jul 16, 2016
Use the tractor supply horse mat and cut away the center and just leave around the perimeter.......That's what I just did to mine.
Vinsil
Explorer
Jul 15, 2016
Jim&Carolyn wrote:
geoboy wrote:

Is your truck a DRW?

No, but the camper is suppose to be made for a 3/4 ton short bed truck and I don't think you can even buy a DRW for a short bed truck.

Ram builds one.

DRW is not the issue.
SoCalDesertRid1
Explorer
Jul 15, 2016
I think the only camper manufacturer that recommends use of the cabover struts is Lance. Other brands may not be constructed such that you want the cabover section to be part of the truck suspension...
diver57
Explorer
Jul 15, 2016
what about the shocks the use see attached to the bottom of cab over and then to the hood do you think that would work
GeoBoy
Explorer
Jul 15, 2016
Jim&Carolyn wrote:
geoboy wrote:

Is your truck a DRW?

No, but the camper is suppose to be made for a 3/4 ton short bed truck and I don't think you can even buy a DRW for a short bed truck.

The AF 811 is a heavy camper, maybe adding 19.5 tires and a sway bar may help your porpoising problem. Is the camper center of gravity at or in front of the rear axle?
Jim_Carolyn
Explorer
Jul 14, 2016
geoboy wrote:

Is your truck a DRW?

No, but the camper is suppose to be made for a 3/4 ton short bed truck and I don't think you can even buy a DRW for a short bed truck.

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is there a crown in the 8 ft box on 16 gmc

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