Replacement 5th Wheel Pin Box for Lippert 1621HD to Provide Better Clearance in Truck Bed

Published 04/14/2016

Question:

MY 5th wheel camper weights 16k and has a lippert 1621HD pin box. I have a 2015 GMC 3500hd short box with a pull rite super glide hitch. I need a shorter pin box to prevent contact with my bed sides when turning. What options are available to me?

asked by: Brian M

Expert Reply:

The best option in a replacement 5th wheel pin box for your trailer to avoid clearance issues with the bed rails is a Sidewinder. A Sidewinder replacement pin box moves the trailer pivot point rearward by 22-inches. This means that the pin box itself will no longer pivot in the hitch (it will be locked in place by a custom wedge # SWW-09), but instead the trailer will pivot at the rear of the Sidewinder, 22-inches further back. This means the pin box remains in a steady position relative to your bed rails.

We offer several Sidewinder pin boxes that are direct bolt-on replacements for your Lippert 1621HD. These include a standard 16K unit # RP34FR and an air-cushioned version # RP61422 that will reduce the effect of chucking and jarring. Both offer the same additional clearance and both will bolt on in place of your 1621HD pin box.

A shorter pin box could lead to clearance issues between the nose of the trailer and the back of the truck cab. You can use the formula below to ensure that there will be enough space between your truck cab and trailer when you are executing a 90-degree turn with the Sidewinder installed.

(A + B) - C = Clearance

A = Distance from center of 5th-wheel hitch jaw to truck cab in inches
B = Length of Sidewinder arm in inches (22")
C = Width of trailer in inches divided by 2

For example:
If you are using the 16,000-lb Sidewinder, then B = 22". If the distance from the center of your hitch to your truck's cab is 36", then A = 36". And if your fifth-wheel trailer is 102" wide, then C = 51".

When we divide 102 by 2 we get 51 inches. Therefore, (36 + 22) - 51 = 7 inches of clearance at the cab.

Please see the linked diagram for the recommended minimum clearance dimensions for 5th wheels.