Saturday, June 26, 2010

Boy, am I over weight (Alaska Trip wise, that is)

Personally, about I need to shed 30 pounds.  In terms of the trip, I've got a real problem.  At least 75 pounds worth.

The problem is that the Expedition Box, loaded, is too heavy.  Its width (48")multiplies the potential weight problems.

American Subaru sets a tongue weight limit of 200 pounds.  Tongue weight is the weight pressing down on a trailer hitch (read Expedition Box in this case).  It's better in Australia .... they allow 300 pounds, probably because they know the Aussies aren't wusses and aren't likely to sue when the vehicle can't take it.

Yesterday I had to dismount the Expedition Box and hook up a utility trailer, so I took the opportunity to weigh the load --- ACK!  325 pounds, including platform, box, and contents.

Too much.  Much too much.  I'd noticed some pitching tendency and some wag-the-dog tendency, not major, but definitely present.  Wag-the-dog comes from leverage exerted by the load on the pivot point.  The box is 4' wide.  If there's 160 pounds on the right side of the box, and you go around a corner, that's exerting about 300 pounds twisting motion on the relatively skinny piece that supports the load.  It's like someone trying to lift a rock from the garden soil.  Pulling on it won't work, but prying it up with a shovel by leaning on the handle works fine.  In this case, the rock is the mounting point for the Expedition Box, and the shovel handle is the length of the box itself -- 2' outboard of the pivot point.  As the car turns left or right, or gets upset by bumps, the twisting force gets applied to the trailer hitch and from there to the axle.  Too much of this is a bad thing.  If there's slop in the system, it's worse.

In the case of the Expedition Box things are helped somewhat by the spare tire stuck between the box and the bumper of the car.  It acts as a damper, reducing the twisting forces and preventing a destructive rhythm from building up.

Even so, I've got to go on a diet.  I can cut out 48 pounds of MREs (meals ready to eat), which I've already paid for, and replace them with MUCH MORE EXPENSIVE food Ill have to buy.  I figure I can reduce the number of tools I'm carrying, and eliminate one or two other things.

If all this sudden diet comes to 75 pounds, that cuts the tongue weight to 250 (plus the spare, which I didn't weigh, but it's mounted so close to the axle that it's not a weight issue, and it's too useful to skip).  With the tire acting as a stabilizer, I figure that will cut the risk of oscillation and significant car damage to a manageable level.

So here's a question, Gentle Readers:  which tools would you eliminate?

1/2 inch drive sockets
3/8 inch drive sockets
heavy duty come-along
power drill
geologists' hammer
crowbar
torque extender (length of pipe fitting over wrench handles, giving the user MUCH more leverage)
hydraulic jack (heavy, but will lift the car better than the toy that came with it)

Over to you.