Fifth wheel pin boxes
MORryde pin box review
A fifth wheel pin box is not a hitch accessory sitting on the truck. It bolts to the trailer frame, under the kingpin, which means it is the trailer side of the connection doing whatever cushioning happens between the road and the cab. A worn or rigid pin box is felt as chuck: the fore and aft jolt that hits on every throttle change, because nothing between the kingpin and the frame is absorbing it.
The MORryde RPB72-1621HD-05 replaces a rigid Lippert 1621 pin box with rubber shear springs that flex under that same load. This review works through what MORryde actually publishes for it, the one rating it does not publish, and when a different mechanism or a different weight range fits the trailer better.
On this page
- What is the MORryde RPB72-1621HD-05, and what does MORryde actually publish for it?
- How does the RPB72-1621HD-05 compare against its own heavier sibling, a rubber torsion pin box and a coil-spring pin box?
- What does MORryde actually publish for the RPB72-1621HD-05?
- What is the limitation of matching a pin box to a GVWR range instead of a weighed pin weight?
- What are the alternatives if the pin weight or the frame does not match?
- What should you check before buying a MORryde pin box?
What is the MORryde RPB72-1621HD-05, and what does MORryde actually publish for it?
The RPB72-1621HD-05 is a direct replacement for the rigid pin box that most Lippert 1621 equipped fifth wheels ship with, using rubber shear springs between the kingpin mount and the trailer frame rather than air bags or coils. MORryde states it reduces the back-and-forth chucking and jerking felt on starts, stops and uneven pavement, and matches this specific model to trailers between 14,000 and 18,000 lb GVWR. A separate model, the RPB72-1621SHD-06, covers trailers above 18,000 lb on the same style of mount.
How does the RPB72-1621HD-05 compare against its own heavier sibling, a rubber torsion pin box and a coil-spring pin box?
All four of these cushion the kingpin connection rather than changing what the trailer or truck can carry. What actually separates them is the mechanism doing the flexing, and whether the maker publishes a pin weight figure or only a trailer GVWR range.
| Published rating | MORryde Pin Box System for 14,000 to 18,000 lb GVWR | MORryde Pin Box System for 18,000 lb GVWR and above | GEN-Y Executive Torsion-Flex Fifth Wheel King Pin Box | CURT Helux Coil-Spring Fifth Wheel Pin Box, 2,950 lb pin weight, 18,000 lb |
|---|---|---|---|---|
| Price | $799.99 | $799.99 | $1,199.95 | $1,537.71 |
| Gross trailer weight rating | not published | not published | not published | 18,000 lb |
| Pin weight rating | not published | not published | not published | 2,950 lb |
Every figure here is the manufacturer's own published rating. A blank is a figure the maker does not publish, and we leave it blank rather than estimating it. The rating stamped on the part you actually receive is what governs.
What does MORryde actually publish for the RPB72-1621HD-05?
MORryde matches this pin box to trailers of 14,000 to 18,000 lb GVWR on a Lippert 1621 frame, and does not publish a separate pin weight figure.
Published standard A published, traceable figure: a standards body, a federal regulation or a manufacturer specification states it.
| Published spec | MORryde RPB72-1621HD-05 |
|---|---|
| Cushioning mechanism | Rubber shear spring |
| Matched trailer GVWR | 14,000 to 18,000 lb |
| Frame compatibility | Lippert 1621 pin box mount |
| Pin weight rating | Not published as a separate figure |
| Fitment check | MORryde Pin Box Fit Chart |
A blank or "not published" row is a figure MORryde does not state for this model, not a figure this table estimated.
What is the limitation of matching a pin box to a GVWR range instead of a weighed pin weight?
The RPB72-1621HD-05 is sold against the trailer GVWR printed on the door sticker, not against the pin weight actually measured on that trailer once it is loaded. A trailer sitting at the low end of its GVWR range and one sitting at the top of it can carry meaningfully different pin weights, and MORryde does not publish a separate pin weight rating the way a coil-spring pin box such as the CURT Helux does. Weighing the trailer rather than reading the GVWR sticker is the only way to know which side of that range a specific rig actually falls on.
The second limitation is fitment. This is a direct bolt-on replacement for a Lippert 1621 frame and nothing else, and MORryde publishes a fit chart specifically because a bolt hole spacing measured edge to edge instead of center to center is a common way to order the wrong pin box for a given trailer.
What are the alternatives if the pin weight or the frame does not match?
A trailer whose weighed pin weight or GVWR sits above 18,000 lb needs the RPB72-1621SHD-06 rather than the standard model. A reader who wants an explicit pin weight figure rather than a GVWR band should compare the CURT Helux, published at 2,950 lb of pin weight and 18,000 lb GTW, or its heavier sibling the CURT Helux 24K at 5,400 lb of pin weight. A reader who wants rubber cushioning through torsion arms instead of shear springs should look at the GEN-Y Torsion-Flex, engineered for a published 2,500 to 4,500 lb pin weight range on the same style of Lippert frame. A reader whose actual problem is cab clearance on a short bed truck rather than ride harshness needs a different part entirely: an extended geometry pin box such as the Lippert L05, which is rigid rather than cushioned.
What should you check before buying a MORryde pin box?
Weigh the trailer pin weight rather than reading it off the GVWR sticker, using the fifth wheel pin weight calculator and the weighing guide, then compare that figure against convention using the pin weight chart. Measure the trailer frame bolt hole spacing center to center against the MORryde fit chart before ordering, and check pin weight for a 14,000 lb fifth wheel if the trailer sits near the bottom of this model published range. See the best fifth wheel pin boxes for how this fits against the rest of the category.
How we chose
We did not test this hardware in person and we never claim to. Picks are researched from manufacturer specification sheets, published towing standards, and the recurring themes in verified owner reviews. Every pick is matched to a real gross trailer weight rating, a real tongue or pin weight rating, a real receiver size or a real load index rather than to a price bracket, and it is placed in the tier where its published capability actually belongs. We rejected the unbranded flood that dominates the search results in several of these categories, because a weight distribution hitch, a brake controller, a trailer tire and a set of safety chains are all parts whose failure puts a loose trailer on a public road. Where a figure is towing convention rather than a published standard we label it that way, and where a manufacturer does not publish a figure we leave it out instead of estimating it.
Sources
- MORryde published specifications for the RPB72-1621HD-05 and RPB72-1621SHD-06
- GEN-Y Hitch published specifications for the Executive Torsion-Flex
- CURT published specifications for the Helux 18K and 24K coil-spring pin boxes
- Lippert Components published specifications for the L05 extended pin box
Frequently asked questions
Does the MORryde RPB72-1621HD-05 increase what my fifth wheel can carry?
No. It changes how the trailer rides by cushioning the connection between the kingpin and the trailer frame, which reduces the chuck felt in the cab. It does not change the trailer GVWR, the truck payload or the GCWR of the combination, which are set only by the trailer certification label and the truck own door jamb sticker.
What trailer weight range is the MORryde RPB72-1621HD-05 built for?
MORryde matches this specific model to trailers between 14,000 and 18,000 lb GVWR on a Lippert 1621 frame. A trailer above 18,000 lb needs the heavier RPB72-1621SHD-06 instead, and MORryde does not publish a separate pin weight rating for either model, only the matched GVWR range.
Does the MORryde pin box publish an exact pin weight rating?
No. MORryde matches this model to a trailer GVWR range rather than publishing a specific pin weight figure. A reader who wants an explicit pin weight rating to check against a weighed figure should compare a coil-spring pin box such as the CURT Helux, which publishes both a pin weight and a GTW number.
Will the MORryde RPB72-1621HD-05 fit any fifth wheel trailer?
No. It is a direct bolt-on replacement specifically for a Lippert 1621 pin box mount. A trailer built on a different frame needs a different pin box entirely, so check the MORryde Pin Box Fit Chart and measure bolt hole spacing center to center before ordering.
What is chuck, and why does a rubber shear pin box reduce it?
Chuck is the fore and aft jolt felt in the cab on throttle changes, caused by a rigid connection transmitting that motion straight from the kingpin into the truck frame. Rubber shear springs in the pin box flex under that load instead, absorbing part of the motion at the trailer side before it reaches the hitch.
Should I weigh my trailer pin weight before buying this pin box?
Yes. Matching a pin box to the GVWR printed on the trailer sticker is not the same as matching it to the pin weight actually measured once the trailer is loaded, and two trailers with the same GVWR can carry different pin weights. Weigh it first using a scale rated for fifth wheel loads.
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Researched, not professional advice. This page is compiled from published standards, manufacturer towing guides and product specifications, and owner-review consensus, not hands-on testing. Figures described as a rule of thumb are towing convention rather than published standards, and they are labelled that way wherever they appear. Nothing here overrides your own ratings. Work your payload sum before your tow rating, because payload is the limit that actually binds on most half ton trucks and nearly every SUV. Load a conventional trailer to 10 to 15 percent tongue weight and a fifth wheel to 15 to 25 percent pin weight, and never lighter: a tail heavy trailer is what starts sway. Weigh the rig loaded rather than trusting a brochure dry weight. A weight distribution hitch and a set of air bags both restore ride height and control, and neither one raises a single rating. Trailer brakes are required by state law above a threshold that varies by state, and a breakaway battery that has quietly gone flat is the normal condition of most trailers on the road.