Do all Box Trucks loose height?

[BradKW]

I couldn't think of an intelligent way to paraphrase this in title, but what I'm wondering is why box trucks seem to loose usable space from the cab back?  For some reason, all the boxes appear sit up higher as opposed to their non-converted brethren.  Or is this just an optical illusion?

 

[Matlock]

If your asking , is the box sitting higher on the frame, then I'd say it depends on the make, model, year and if it's for fleet use or a limited production.
I would guess the load capacity could play a roll as well.
However, If I'm not understanding your question I'll take another stab at this once you reply.

 

[BradKW]

If your asking , is the box sitting higher on the frame, then I'd say it depends on the make, model, year and if it's for fleet use or a limited production.
I would guess the load capacity could play a roll as well.
However, If I'm not understanding your question I'll take another stab at this once you reply.

Yep, that sums it up well...it appears to me that the boxes sit up higher, whereas the unmodified vans have a lower floor....

 

[TMG51]

Well, the one in your picture has the box set low enough to be into the wheel wells... some sit totally above the wheel wells... seems to me that might be a good way to eyeball estimate this.

 

[LeeRevell]

A few good tie-downs will prevent loose items from moving about.

 

[speedhighway46]

When the "box" is put upon the frame rails of the vehicle chassis, normal practice for the up fitter doing the work is to place a 2x4 or 4x4 in between the two running the entire length of the frame on both sides. Depending upon the size of the stock, or none at all, is why boxes appear higher than others.

When building our Peterbilt Motorhome, the up fitter used 2x4 stock because I wanted the top of the box to align closely with the top of the cab. If I had wanted it just a bit higher he gladly would have used 4x4s. The stock used was regular, untreated 2x4s. When asked why they were not using pressure treated runners they explained that those have a tendency to shrink and the box loosens slightly on the rails and could shift just a bit.

 

[TMG51]

A few good tie-downs will prevent loose items from moving about.

Yep, wouldn't want to lose and loose items; particularly your dessert while driving through the desert.

 

[masterplumber]

Most boxes are also built with a frame under the floor, similar to a flatbed. This makes them much stronger and also they don't rely on the vehicle frame for their rigidity. On the regular van bodies there is usually no floor member running parallel to the van frame, just horizontal members providing the support, and these horizontal members are also usually smaller in size. Added up, along with the wood that Speed Highway mentioned, and it adds up to several inches height difference.

 

[Matlock]

Some additional info on Chassis..

Ford Transit

Promaster

GM Cutaway

Details of Chassis by manufacturer.
http://walkinvan.com/walkin-chassis-information.htm

 

[Matlock]

Forgot to add the Step Van
Freightliner UPS truck, LPG Step Van

These are all newer model frame designs so expect to see some variations under all earlier van/truck builds.

 

[speedhighway46]

Nice pictures, Matlock!

Here are some more pictures showing frame rails and runners; different views of preparing and setting the box on our Peterbilt Motorhome build in 2010, as follows:

1> This is the frame all prepared and painted; fifth wheel removed and frame extended 4' in the rear.
2> The box being put into position over the frame rails.
3> Final lowering of the box; note the 2x4 runners sitting on top of the frame rails. These match up to the supporting beams of the box.
4> We specified the height of the box, and final adjustment using the thickness of the 2x4 runners to have the top of the box align with the top of the sleeper.

 

[Rugster]

What a cool thread, I learn so much from this site. I had resisted clicking on the thread for a day or two because I was going to post something snarky like:

'If your box truck is losing height, put more air in the tires'

Of course, noone else thinks like I do and posted informative and interesting posts