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stillcampin's avatar
stillcampin
Explorer
Oct 06, 2015

5th wheel setup questions (long)

TIA, & sorry for the book and all the questions.

I may be worrying about nothing, but in selecting a 5th wheel towing setup how do you ensure you have adequate clearance between the top of the truck bed rails and the base of the 5th wheel where the king pin mounts?



I have my 5th wheel measurements and the specs for my future tow vehicle when unloaded. The bed rail height of the unloaded truck is almost 1" higher than the clearance under the nose of the 5th wheel.

I realize the height of the truck bed rails will drop once the couple tons of pin weight are added but the 5ver will be bowing along with it.

Thus, it appears to me that there are two possible ways to correct this: 1) an extended hitch pin would add distance, and 2) the height of the hitch in the bed of the truck would lift the pin height.

Thus, I assume, it would be a good idea to consider hitches that are sufficiently height adjustable to get the necessary clearance.

In my case, my existing pin box extends approx. 12" below the skin of the 5ver. The unloaded truck bed rails are almost 57" from the ground with the rails themselves rising a tad over 20" above the bed of the truck.

If I'm calculating right, the base of my pin box should be at least 14" above the bed to have the necessary clearance above the rails.

Am I thinking right that the hitch I need to get this height needs to be at least 14" high (per its specs)? And, if I need bed rails, is that included in the specified height of the hitch?

I'm currently looking at a couple of hitches: one is made specifically for the truck and is a 'puck' mount that is 14" high (non adjustable) and another requires rails and is adjustable from 14" to a few inches higher.

Leveling the 5ver after hitching shouldn't be a problem since the truck I'll be ordering will have adjustable suspension. But would I be better off getting the adjustable hitch?
  • You are not saying what truck you have, or what actual hitch you are considering.

    I would take advantage of the factory puck system, if available, on the truck you are considering. B&W makes an adjustable hitch for the puck system trucks.

    You need to give more info on the truck, and hitches you are considering. You may get more replies on the FW forum. It does seem that you have a pretty good idea of how to figure/measure, to see what will work for you.

    Jerry
  • rhagfo's avatar
    rhagfo
    Explorer III
    MFL wrote:
    You are not saying what truck you have, or what actual hitch you are considering.

    I would take advantage of the factory puck system, if available, on the truck you are considering. B&W makes an adjustable hitch for the puck system trucks.

    You need to give more info on the truck, and hitches you are considering. You may get more replies on the FW forum. It does seem that you have a pretty good idea of how to figure/measure, to see what will work for you.

    Jerry


    X2, In reality the OP needs to give specifics on the 5er, hitch and TV. Now days 57' to the top of the rail is pretty standard. If you like the 5er and TV get them then do what is necessary to get near 6" clearance and the 5er level.
  • I didn't mention any specifics because I was not wanting to invite personal preferences into this particular discussion. But, since it seems to be desirable, here goes ...


    My timeframe will make it a 2016

    Puck mount

    Mounting rails required




    And my rig



    Montana 3900FB
  • You're asking all the right questions and hopefully someone with the exact TV will chime in with an opinion.
  • After reading your post more thoroughly, your math is correct. I don't know why knowing what exact truck and/or trailer matters, though. Anybody can do simple math. It's not special "Dodge math" or something like that.

    To get 6" clearance between the 20" high bed rails and the underside of the 5th wheel, you will need a total of 26" of height. Setting the top of the 5th wheel to 14" above the surface of the bed, combined with the pin being 12" below the overhang, will give you that 26".

    That gives you a good starting point, but be prepared to do some trial and error work just in case. You may need to go up or down an inch or two to get things dialed in perfectly.

    The only issue you may have is getting things level. That truck's suspension may not let you lower it enough, or if it does, the truck may end up sagging in the back with the trailer level. You still might have to flip the trailer axles, or if they already are, you may need to install some "hockey pucks" for a couple more inches of lift.
  • Thanks. I think I've read that the Dodge might be a tad high which is the reason for my post. It looks like flippin axles may be in my future, plus a ground step for the stairs.
  • It's not just the Dodge. Trucks in general have been getting higher and higher, with deeper and deeper beds.

    I never had a problem getting into my 2003 Silverado 1500, but if I don't put running boards on my new 2015 soon, I'm going to ruin the seat climbing in. The bleepin' thing sits 6" higher than the old truck.

    Why the manufacturers think everybody likes/wants that huge jacked-up look, I don't know. Who wants to lift 80lb bags of concrete up 4' to get them into the bed of one of these monstrosities?

    It's going to be a problem sooner or later with these giant McMansion 5th wheels that are already pushing 13' tall... If you've got to raise them another 6" to get one of these trucks underneath to tow 'em... There are going to be a lot of AC units knocked off.
  • OP, they are tall but you can make them work. I have basically the same truck you are looking at and my 5er is pretty much the same as yours (measurement wise) My truck settles around 2.5-3 inches when the pin weight is applied. My 5er runs very slightly nose up (which I personally prefer). I use a B&W Companion for my hitch. I think you will be just fine with that truck.

    You can see the whole truck in this picture but you can see the attitude of the truck and 5er and how they sit. I have 6" of clearance between the bed rail and underside of the 5er.



    Moderator edit to re-size picture to forum recommended limit of 640px maximum width.

  • Same worry here. My bed rails (2010 Ram 3500 4X4 SRW crew cab 6.5' bed) are 59.5" from the ground with a 200~lb. shell mounted. The one fiver I like (GD303RLS)is 61" from ground to the underside, and it comes with the axels flipped AND a 2" spacer bar on the frame. The other, (GD 317RST), a couple of feet longer, is 59" to the underside. Pin weights would be 2000-25000 lbs. so the squat would not be as great as in the OP's case.

    Another manufacturer gave me 48" as the "pin box height", which is not what I asked them. I don't think either the truck or RV companies have much of a clue.

    The manufacturers will not give the OK to tow nose high and might use doing so as a reason to void a warranty if something failed.

    Not sure what is the answer.
  • I have just dealt with this same issue. I was worrying and doing math, because the back corner of my Dodge 3500 4x4 is 59". When I hitched to the 5er, it was fine. Also, some 5ers have adjustments at the spring shackles. You just need to back under it and see how it sets. Happy towing!

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