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Re: [RC] Shortbed trucks - Laney Humphrey

Thanks, David & wife. I'm adding this post to my "trucks and trailers" folder.
Laney


David LeBlanc wrote:
Tichenor06 said:
        
I have a short bed. I know MANY others that also have them. Truck beds
are like horse backs.  Shorter is stronger.  With any trailer bumper or
goose with any truck long or short or flat, you have to learn and know what
you can and can not do with regards to turning.  Go out in a pasture or
parking lot and drive it around so you know what you can do and what you can
not do.

This isn't completely true. First of all, trucks from the same manufacturer
don't all get the same suspension. The frame isn't going to be your limiting
factor - the suspension will be. The way to figure this is by looking at the
GVWR - gross vehicle weight rating. This is the heaviest the truck can be,
including cargo. In your Ford Super-Duty truck line, the lowest GVWR is on
the shortest truck at 8800#, and the longer trucks go up to 10,000#. This is
partially to compensate for the added weight of the bigger truck itself, and
won't show up in the maximum payload, which ranges from 3200# down to 2600#
(1.6 tons to 1.3 tons - so much for the 1/2 ton, 3/4 ton, full ton stuff -
even the F-150 can handle anywhere from 3/4 ton to 1.5 tons). If you go up
to the F-450 and F-550, then you get a GVWR of 16,000#, and the carrying
capacity on the bed goes up to close to 5 tons.

It's also not true that the truck doesn't carry much of the weight. If
everything is standing still, that's fairly correct - but it's still around
1/4 of the total trailer weight, so for our 33' trailer, 1/4 of the total is
2 tons (fully loaded). Our trailer would overload a normal Super Duty truck
standing still. For the Chevy fans - they have a lower load carrying
capacity. Now figure what happens when the trailer goes to stop. The trailer
brakes are ideally doing most of the stopping of the trailer, and the truck
isn't stopping the trailer or vice-versa. What this means is that the whole
thing wants to pivot on the trailer wheels, and the nose of the trailer
wants to go down, putting a lot of load on the bed, much more so if you're
pointed downhill. On our older Chevy, which was overloaded, this would cause
the front wheels to shimmy violently under these conditions because the
suspension was so overloaded, it wasn't tracking right. The vehicle wasn't
steerable under those conditions. Our F-550 is loaded well under capacity,
and we've never seen any of those problems. This also shows that shorter
isn't stronger - that F-550 has the longest wheelbase you can buy. The whole
thing is so long it won't fit in a normal parking spot. But that's one of
the platforms they build tow trucks out of.

Next, the longer the wheel base, the better the vehicle will be able to
resist side forces, and you don't end up with the tail wagging the dog. This
is another reason to go for a longer wheel base.

Now for _your_ trailer, _your_ truck might match up just fine, and be
completely safe. People keep asking the wrong question, which is "what will
it pull?" The right question is what will it stop, and what happens if I
have to nail the brakes going downhill - will I still be in control of my
vehicle?

The way to answer these questions is by understanding GCVW and GVWR. The
first is what the combined truck, trailer, horses, tack, hay, water, and
people weigh all together. The second gives you an idea of the load you can
put on the bed of the truck.

The next question is just geometry - so if the gooseneck ball has to be just
forward of the rear axle, can we put the truck at a 45 degree angle to the
trailer, and not hit? If that works, can we get to a 90 degree angle and
still not hit? Do you want a truck that only pulls your trailer, or one that
pulls any gooseneck? Effectively, this means you need just over 4 feet (48")
between the ball and the back of the truck cab. The Super Duty 8' cargo bed
handles this just fine - it's 98" long. The shorter bed style may not,
depending on where the axle is relative to the bed - it's only 82" long. I'm
using Ford as an example because I can easily find the specs, but the same
thing applies to any manufacturer.

Another consideration is this - say you have the truck at 45 angle to the
trailer, and then you put one side of the trailer in a hole, and it is
tipped over. The outside corner of the trailer nose comes down. If you have
something on the bed, is there clearance for this? We unfortunately didn't
figure on this part until we were on our way to our first ride and
rearranged one of the toolboxes =8-O

The funny thing here is that I learned all this listening to my wife 8-)
She claims this (me listening) rarely happens, but one day I was thinking
about buying an F-350, and was talking with the salesman about interior
options, and she was reading the towing guide and doing the math. The
question of bed dimensions came up, and on the way home to find out what we
needed for trailer to clear, she pointed out much of what I just outlined
above.



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Ridecamp is a service of Endurance Net, http://www.endurance.net.
Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp
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Ride Long and Ride Safe!!

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