I am preparing to mount a new/used 5th wheel hitch, how far should the pin center be ahead of the axle?

 

Normally I'd recommend just over center. I would think you could find instructions online for the type of hitch you have.

 

FWIW the center of the B&W hitch in my truck is 46" from the end of the bed. Like Scott said, I would try to find instructions online for your hitch.

 

Go to the web site for your brand/model hitch. Install instructions are there.

 

When I put my Reese 16k in, the brackets made for the installation were set up to be directly over the rear wheels.
I think you will find every mfg set's up that way. Only makes sense to balance the load.

 

Actually I think you will find they sit a few inches IN FRONT of centered over the rear wheels......

 

Bud,
You are right. Thanks for correcting me. I just went out and measured and it's pretty close to 3" forward of the rear axle.
My apologizes on this one.

 

HAHAHA= No problem Bob..... you should see MY collection of corrections!!!! Reps to you!

 

Judging by Ford_Six's signature and profile, he may be mounting this hitch in a truck old enough that kits and instructions may not be easily available.

If I am right, some on the job training might be required. About 3" forward of the rear axle centerline is a good spot. Anything 2"-4" will work fine. And most importantly, make sure you are mounting this hitch to the frame, NOT to the bed. That may seem too obvious and insulting, but this mistake has been made before.

 

I have set up quite a few gooseneck hitches, and usually put those about 4" in front of the axle centerline. I wasn't sure if a 5er was the same, but sounds like it's pretty close.
This is the last step in getting my brother in law's truck out of my driveway. It started out as an 88 F350 crewcab longbed 4x4 with a massive lift and twisted frame, now sitting on an 81 E350 1.25 ton RV chassis. It's been a long and interesting project, mostly broken up by his unwillingness to spend money on this truck he asked me to build.
The hitch is an unknown brand, designed to bolt into the bed of a truck so it's a lighter duty hitch, maybe 10-12k. His only trailer is a 28' Alpenlite so I doubt he'll be pushing the limits of the hitch. Besides, his towing experience consists of pulling a 4x8 trailer behind an Astro to the dump maybe once or twice, so I don't expect him to tow this that much anyways.
I mounted a pair of 4x1/2" angles to the frame to mount the hitch on, I'll just bolt the hitch to those. There is about 1" of adjustment in the mounting slots.
Thanks for the input guys.

 

Yep, Yep, Yep, on or slightly forward of the rear axle. A 5er can be as wide as 8.5 ft and 1/2 of of that is 51". Ideally, at least 52" measured from the back window on a long bed, so that measure will keep you out of your rear window. Obviously with a short bed, that is impossible hence the need for a slider hitch and/or extended pin to keep your hitch on top or a hair in front of the rear axle. Mine is right on top of the axle and have not had weight issues as I have weighed on several occassions, fully loaded.

 

it isn't so much weight issues, but handling issues with heavier trailers.

a 5th wheel/gooseneck is supposed to place weight on both front and rear axle of the tow vehicle, not just the rear. This is because of the dynamic forces. If you are simply looking at the static forces, it seems okay, but when you remember that the weight of the trailer (load) is putting a moment on the rear axle that is only counteracted by the weight of the front of the tow vehicle it makes more sense.

When you go, the trailer tries to lift the front of your pickup off of the ground. If you don't add any of the tongue weight to the front axle, you might as well have just bought a conventional trailer.

That does work both ways, too... too much tongue weight added to the front (hitch point too far forward, and you'll increase wear on your steering system and make it difficult to turn.

 

Thanks for explaining the what and why's? I myself am looking to set up my truck for a 5th wheel and I have been following this tread in hopings of understanding more about 5th wheel towing before even buying a 5th wheel hitch or trailer. Thanks reps sent

 

I've been looking at instructions on etrailer for universal rails and F-150 specific rails and they are written by the manufacturer at 1 1/2" in front of the axle centerline.

 

Interesting, I wonder if that has anything to do with the length of the bed? Does it actually say in front of axle centerline, or in front of wheelwell centerline though? Usually the wheelwell bump leads the axle by a couple inches.