Compensating for GM crowned bed

[dhull]

I didn't discover this anomaly until about a year in when I noticed denting occurring in the front of the bed and on the camper where it meets the end of the bed. A result from the rocking motion from the built in see saw. Also noticed the distance from the bed rails to the camper was not uniform from front to back. Gap was less at rear.







So I made a wedge using 3 pieces of 3/16" wood sheets glued together. So its 9/16" on thick end and 3/16" at the thin end. Its 50" wide and 21" long. Then I slip that under the rear of my Dee Zee bed mat.



As you can see the mat leaves rubber on the wedge but little on the thin end leading me to think its too thick at 9/16" or too long.

So I wanna make another using 24" x 30" trucker mud flaps which will need trimmed.
MY QUESTIONS....
About how much drop is there on a 2016 Chevy short bed from the crown to the end of the bed?
Can I ignore putting anything on the other side of the crown?

[Avid_Fox]

On Ford trucks the bed is deeper at the back, to the top rails. Always makes campers look like they're falling off the back of the truck. 😞

How has the shimming worked for you? Road tested yet?

[Avid_Fox]

"Any more expensive and it's gonna be more profitable to sell your house in pieces!"

Now that's funny!!!

[Avid_Fox]

Z-Peller wrote:
My 2016 GMC long box is 7/16" drop at tailgate when straight edge is run from front of the box.
I need lift for my camper and use two 4'x8' 3/4" sheets of plywood. I shim those with a 1/2" x12" plywood piece across width of box at tailgate.

I have the same crowning issue on my 2016 Ford f350 dually. It's a bother, as it allows for a lot of camper rocking and stress cracks on the tail of the alum bed.

[MORSNOW]

dhull wrote:


So I cut my mud flaps back to 15" and added a 3/16" board in front of the thick portion of it to form a wedge of sorts. So I got the 7/16" thick at the back for 8" then its 1/4" thick out to the 15".

Thanks for all the replies...

Looks good, keep us updated. Thanks

[dhull]

So I cut my mud flaps back to 15" and added a 3/16" board in front of the thick portion of it to form a wedge of sorts. So I got the 7/16" thick at the back for 8" then its 1/4" thick out to the 15".

Thanks for all the replies...

[Bert_the_Welder]

Z-Peller wrote:

....Shows pic of a Canadian 2x4...... a Newfie Straight edge

Nope, not a H depot airplane propeller...this one eyeballed carefully before using and was straight...my 4 foot level was 4 feet too short for this job.:B

LOL! And even at $9 each, they didn't get any straighter! 😄
Any more expensive and it's gonna be more profitable to sell your house in pieces!

[dhull]

Z-Peller wrote:

....Shows pic of a Canadian 2x4...... a Newfie Straight edge

Nope, not a H depot airplane propeller...this one eyeballed carefully before using and was straight...my 4 foot level was 4 feet too short for this job.:B

Thats funny! I couldn't use my 4 foot level either even on my short bed truck.

I haven't seen a 2x4 that straight for 30 years!

I got plan now, will post pics...

[Z-Peller]

....Shows pic of a Canadian 2x4...... a Newfie Straight edge

Nope, not a H depot airplane propeller...this one eyeballed carefully before using and was straight...my 4 foot level was 4 feet too short for this job.:B

[MORSNOW]

dhull wrote:
Didn't you trim some off the length of your mats?

No, you can buy semi mud flaps in different lengths, I think mine are 24".

[Bert_the_Welder]

Z-Peller wrote:
when straight edge is run from front of the box.

....Shows pic of a Canadian 2x4...... a Newfie Straight edge :B

[Z-Peller]

My 2016 GMC long box is 7/16" drop at tailgate when straight edge is run from front of the box.
I need lift for my camper and use two 4'x8' 3/4" sheets of plywood. I shim those with a 1/2" x12" plywood piece across width of box at tailgate.

[dhull]

MORSNOW wrote:
There is a center crown in the box around the axle area to allow water drainage front and rear, it is obvious when I ran a 4' level lengthwise in the box. I put two rubber semi mud flaps side by side in the back half under my rubber camper mat, problem solved.

Didn't you trim some off the length of your mats?

[MORSNOW]

There is a center crown in the box around the axle area to allow water drainage front and rear, it is obvious when I ran a 4' level lengthwise in the box. I put two rubber semi mud flaps side by side in the back half under my rubber camper mat, problem solved.

[Geo_Boy]

I first placed a 1&13/16” thick x 6” high piece of lumber across the front of the bed with a a 3/4” thick piece of HDPE attach to the lumber to keep the TC off of the front of the truck bed. I have a rubber bed mat in the bed, then I placed a piece 1/2” thick horse stall mat on the rear of the truck bed to compensate for the crown. I placed a straight edge, front to back, to find where the crown started to tapered to determine where to place the shim.