Correcting A Demco Adapter 6333 Loose Fit

Updated 10/19/2021 | Published 01/01/2020

Question:

I have installed the Demco 6333 adapter on my 2020 Sierra 3500 short bed. Once I loosened the four bolts per corner, the unit landed easily into the factory pucks. I was able to close the levers and lock easily once the unit was in place, but i have about 1/8inch movement when I try to lift the rear of the unit while locked in. Is this normal, and if not, how doe I correct?

asked by: Luis B

Expert Reply:

If you have some slop after installing the Demco 5th Wheel Rail Adapter for Chevy/GMC OEM 5th Wheel Towing Prep Package # DM6333, you can try to adjust the washers by adding more to one side and/or taking them away from another.
If one handle feels tighter than another, that is a good sign that you just need to adjust the washers but the pucks are also not always level from the factory.

Included is page 2 of the instructions providing more detail about the washer adjustments.

expert reply by: Patrick R

click to enlarge

Art P.

4/19/2020

I have a similar issue where the Demco6333 seems to have a little rocking action after installation. All handles have 2 washer shims and it appears another washer shim added to one handle may tighten the frame up. I need to know if adding a third washer shim to just one handle will be ok. If so then do y’all have these washers/shims for sale. Also, if I do add a shim then now I will need the torque specifications of the nut that holds the handle system together. Is there anything special about this nut. It says it is PN 00173 Nut Hex, .50 NC Center Punch.

Chris R.

4/21/2020

I reached out to my contact at Demco to get his thoughts on this. He said that they do see some variance from truck bed to truck bed. Unfortunately they're not all exactly the same, which is why those 2 shims are included if needed. My contact said he's honestly not concerned with your setup as-is. Once a hitch is placed in the 6333 and a trailer is attached, the pin weight is going to keep everything in place. It's not going to move once hooked up. He doesn't recommend adding that additional shim.

Michael T.

3/16/2021

I purchased a demco 6333 adapter plate for 2021 2500 and i have a problem with chunking since the hitch is new ,it seems to be the adapter plte moving how to solve the movment noise

Jon G.

3/18/2021

@MichaelT Does it move when you have a hitch installed and a trailer hooked up or only when you're driving around without a trailer? Also, have you messed with the shims at all like what ArtP and ChrisR were talking about above?