Picking a Wheelbase

[ReluctantTraveler]

I'm planning to build my custom camper on an F-550/5500 crew cab platform, and am trying to figure out the optimum wheelbase.

One of the design goals/compromises is trying to maximize interior space while maintaining enough nimbleness to go places a bigger class A or 5th wheel cannot. As it is, our small travel trailer + SUV makes getting in-and-out of places annoying, so I imagine a driveable will be a slight win there from the start.

The design has a cabover bed, dining/second bed in the rear, and a majority of the water system and batteries between the two axles in a 1' basement. The main box is ~12-13' long

1. The 203" wheelbase would give us a Cab-Axle distance of 84", and allow for a 12' flatbed.
2. The 179" wheelbase would give us a Cab-Axle distance of 60", and allow for a 9' flatbed.

The shorter wheelbase has more availability in the used market, and would have a tighter turning radius. BUT, it would mean an angled overhang of 3-4' off the back of the flatbed. While the turn radius would be tighter, the overhang would have a lot of swing I'd have to be cautious of while driving.

It also potentially exceeds Ford's recommendations on max length, though with much of the weight mid-axle, I'm not sure it's a serious concern.

The longer wheelbase would have no (or almost no) overhang and thus less tail swing, but a wider turn radius overall. Construction would also be easier with less of an angled rear to construct.

We're mostly campground and service road campers. No heavy off-roading for us.

Any thoughts, feedback, and experience welcome!

 

[1000arms]

The 203" wheelbase has less of a breakover angle than same setup with the 179" wheelbase, but for campgrounds and service roads, it probably won't matter to you.

The 84" CA will help you create the interior space you want while allowing you to still tow without needing extensions to your hitch. As long as the overhang of your camper isn't too long, and as long as you slope the bottom of the camper up enough at the end of the flatbed, you should be able to tow with the factory hitch for the roads you will likely be on. This will also allow you to use a receiver-hitch bike-rack more easily than a longer overhang on the the 60" CA.

 

[ReluctantTraveler]

The 203" wheelbase has less of a breakover angle than same setup with the 179" wheelbase, but for campgrounds and service roads, it probably won't matter to you.

The 84" CA will help you create the interior space you want while allowing you to still tow without needing extensions to your hitch. As long as the overhang of your camper isn't too long, and as long as you slope the bottom of the camper up enough at the end of the flatbed, you should be able to tow with the factory hitch for the roads you will likely be on. This will also allow you to use a receiver-hitch bike-rack more easily than a longer overhang on the the 60" CA.

That's been my thinking as well, as I do plan to use a hitch-mount bike rack if I can. I figured I'd need a big slope on the rear overhang with the 60" CA for a variety of reasons.

I'm not terribly worried about breakover angles given how we generally camp, though fair point!

The biggest advantage to the 60" CA is that with the camper off the bed, we're 2' shorter and thus parking and driving around places is a bit easier.

 

[1000arms]

... The biggest advantage to the 60" CA is that with the camper off the bed, we're 2' shorter and thus parking and driving around places is a bit easier.

It would help a bit, but, the CC 60" CA length is similar in length to a F350 CCLB, and the CC 84" CA is similar in length to a F350 CCLB with the tailgate down. Yes, the 2' does make a difference, and the difference is in length and in wheelbase (unlike the CCLB to CCLB with the tailgate down), but both are extra-long vehicles as far as most parking spaces are concerned.

 

[ReluctantTraveler]

but both are extra-long vehicles as far as most parking spaces are concerned.

That's a good point! Even with the shorter wheelbase, the crew cab truck is still quite long.

 

[hoodlum]

Hey RT, you’re reading my mind here…we’re in the same boat.!!!

We’ve been back n forth as well on the 60 vs 84 CA.
Also a 2 vs 4 door. I plan on a pass thru to the cab and a 2dr would make that easier.
Our E450 rig was..perfect..for that feature. I should’ve dropped a Cummins in it and kept it..Ha.

As of today… 4 door n 84… is the plan. Ram 5500, 6.7.

Many good points… 1000arms and Klahanie.
We don’t care for the look of the overhang to far past the axle. Plus departure angles need to be considered.
I don’t care for hitch extensions myself.

 

[ReluctantTraveler]

Fwiw you can prob get an 12' deck for a 84ca and maybe a 10' one for a 60ca ( mine is close to that).

Yes, I can. I'd planned to angle the rear of the camper body just a foot off the back to give us that little extra interior space (maybe, probably), but it's pretty close to where we need to be.

One point about the rear swing or "sweep" when turning you mentioned is.... it works both ways. Backing into a spot can require more room for that swing or more repositioning.

That's a good point. Sounds like the longer CA is probably the better option for me.

 

[ReluctantTraveler]

Hey RT, you’re reading my mind here…we’re in the same boat.!!!

Nice! We've got a family of four (plus a dog), so it has to be the the crew cab for us.

We're in a 16' travel trailer right now, and... it's a bit cramped!

 

[ReluctantTraveler]

Just to illustrate what I was talking about, this Host 330 is 35' long. Look how far past the rear axle the back of the RV extends.

 

[AbleGuy]

⬆ the longer your big booty hangs over the rear axle, the more nasty shakin is gonna be going on.

We once had a setup with too much rear overhang and on bumpy roads (and on those horrible ‘getting to the back of beyond and coming home’ cement jointed hwys) the hopping was not only annoying and distracting, but it always shook stuff loose inside the camper!

It was an interesting puzzle solving exercise some evenings, once finally in camp, to try to find out what the loose, errant screws lying on the camper’s floor belonged too?

 

[ReluctantTraveler]

⬆ the longer your big booty hangs over the rear axle, the more nasty shakin is gonna be going on.

This was all great advice, but I'd really love to see the rear of the camper formally named "big booty" going forward ???

 

[AbleGuy]

I’d post a pic for y’all but it’d get me Chilli banned ?

 

[simple]

my vote is for shorter wheelbase with a 11-12ft box. I'd use the rear overhang for a set of bunk beds for the kids.

 

[ReluctantTraveler]

my vote is for shorter wheelbase with a 11-12ft box. I'd use the rear overhang for a set of bunk beds for the kids.

Current floorplan has the dinette in the rear, with murphy-bed for the kids built in the dinette backrests.

One of the things we hate about the bunks in our travel trailer is that for a majority of the day they're just wasted space, but we really appreciate not having to make a bed each day. This feels like a nice compromise.


This also feels like it keeps most of the weight up-front, but I do worry about tail swing.

 

[simple]

Current floorplan has the dinette in the rear, with murphy-bed for the kids built in the dinette backrests.

One of the things we hate about the bunks in our travel trailer is that for a majority of the day they're just wasted space, but we really appreciate not having to make a bed each day. This feels like a nice compromise.


This also feels like it keeps most of the weight up-front, but I do worry about tail swing.

When you say tail swing are you talking about an un stable condition going down the highway or a dimensional clearance thing when turning?