Community Forums

Roadhazard · 06-23-2007, 05:03 PM

I have a short bed truck(7') with a slide hitch. I was entertaining the idea of an R5 pin extention until I read it requires welding the extension to your pin box. So the question is, could you have a custom pinbox made with an extra 10" length in the box itself or would this cause problems in towing?

Roadhazard · 06-23-2007, 05:03 PM

I have a short bed truck(7') with a slide hitch. I was entertaining the idea of an R5 pin extention until I read it requires welding the extension to your pin box. So the question is, could you have a custom pinbox made with an extra 10" length in the box itself or would this cause problems in towing?

RustyJC · 06-23-2007, 05:19 PM

That's a question that really needs to be posed to your manufacturer. It depends on the weight of the RV and the design criteria used for the frame. Some 5th wheels can handle an extended pin box with no problem; others (such as our previous 5th wheel) came with a straight (vertical) pin box, and an extended pin box was not an option, nor would the RV/frame manufacturers approve the use of one.

Rusty

Ray,IN · 06-27-2007, 03:31 PM

If you own a Zieman/Lippert frame read the warranty closely. If the manufacturer says "any frame modification will void the warranty", I believe them. They designed and constructed it.

Roadhazard · 06-28-2007, 01:50 PM

Yes it is a lippert hitch. I guess I will not have an extended pinbox for atleast 2 years for sure. I currently have an "extended" Lippert model LIPP1621. I was just wondering what adding 10 more inches to a pinbox would do to weight distribustion. I was even looking at the 5th Airborne pinbox but thats out too now. Thanks for the response and the info. Doug

TXiceman · 06-28-2007, 02:34 PM

Adding more length by extending the pin box or raising the pin location with a goose neck adapter increases the moment arm seen the the frame at the pin attachment point. The frame is designed to carry normal loads, not the excessive loads created by increasing the length of the pinbox. if you are an engineer, it is pretty easy to look at the forces on the pin and surrounding frame.

I have seen two 5ers with frame damage due to the use of a GN adapter. Not cheap to repair.
Ken