Extended Pin Box Mod

[chevyrod]

I'm installing an extended pin box on a 1984 Mallard 24' fifth wheel. The original pin box is straight and will not allow enough clearance for my short bed pickup. Of course the old pin box mount is one inch narrower than the new style extended box. My question is, is it ok to just weld the new box on, or is bolting it in place sacred? I plan to reinforce with 1/2" drop plates and install stress rods to tie it all in place, and welding will be significantly more efficient than drilling new mounting plates. King pin height adjustment isn't an issue. I know the finished product will be much stronger than original. Any suggestions or thoughts on this project? Thanks.

[chevyrod]

I'm installing an extended pin box on a 1984 Mallard 24' fifth wheel. The original pin box is straight and will not allow enough clearance for my short bed pickup. Of course the old pin box mount is one inch narrower than the new style extended box. My question is, is it ok to just weld the new box on, or is bolting it in place sacred? I plan to reinforce with 1/2" drop plates and install stress rods to tie it all in place, and welding will be significantly more efficient than drilling new mounting plates. King pin height adjustment isn't an issue. I know the finished product will be much stronger than original. Any suggestions or thoughts on this project? Thanks.

[charliez]

Why not just get a slider hitch? Then there's NO modification, and you may have issues selling the rig later after it's been modified. Especially in the hitch area.

[chevyrod]

Charliez: I already have a hitch installed in the truck, RBW Little Rocker and don't really want to spend the extra cash for a slider. Plus cab clearance is way too close as the stock kingpin is under/inside front of camper by about 10", making cab/coach clearance only about 29" so with or without a slider this dim stays the same for "locked" towing.

[charliez]

You may also consider upgrading to a LWB TV. With the gas prices like they are, many will be coming onto the market soon.

[charliez]

Plus, I know I'd be learing of pruchasing a rig with a modified hitch. I'd have to wonder if the original got tore off amd the new one got properly put on.

[allendp]

Kinda depends on what you plan to do with the rig. It being a 1984 model, you could not expect to get a whole lot fot it if you did sell it. If your goal is to keep it for a few more years along with your current TV, I'd say go for it. You sound like you know what you are doing. You might consider getting it inspected by a professional, just to make sure it's roadworthy after you complete the job. Good luck.

[chevyrod]

allendp: You're right about the value, I picked it up for a decent price and it is a clean well cared for unit. My goal is to have a dependable unit for hunting/kayaking and very occasional family outings. After looking at tons of used 5th wheels within budget (even out of budget) this one clearly stood out. It did show the obvious exterior damage of sun and time though. Thanks for the vote of confidence, my wife however may disagree... Project complete, am pleased with the results. Spacing differences of pin box worked out with the correct drop plates and all is well. The new hitch is much stronger than original, provides plenty of cab clearance as well as tailgate clearance when in down position during hookup. I haven't towed with it yet so official final test is forthcoming. I also flipped the axles, stripped all decals and pinstriping (whew!) and exterior is awaiting new graphics. Now for a good cleaning, new tires, a little brake/electrical work, repack wheel brgs, etc. etc. and should be good to go.

[C Driver]

It is possible that the extended pin box will place undue twist and pressure on the fifth wheel support frames ...... just be careful