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Old 01-06-2017, 05:14 PM   #1
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I was wondering...

and I simply don't have a mechanically inclined intelligence (fortunately nature has more than compensated with a surfeit of charm and movie star good looks) but I was trying to figure this out.

We've had snow and ice in Portland. I have a rear wheel drive Sportsmobile.

In the past, with other RWD vehicles, tossing a couple hundred pounds of sand in the back has made a marked difference in traction, particularly when taking off from a complete stop.
I wonder, given the sportsmobile weight, if this additional weight would even be noticeable?

The Big Question:

Would placing the weight farther back, let's say six feet from the center of the rear wheels (on a hitch carrier) have a larger influence on traction than placement immediately above the rear wheels; as a result of the conservation of mass, the law of the lever, the momentum of fulcrums, or the original sin theory?
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Old 01-06-2017, 05:30 PM   #2
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The weight helps in icy conditions but tires ( with chains or studded tires in the case of ice or slick snow) are going to have a greater impact on traction than a few hundo in sand bags. Vans already have a pretty good amount of weight on them and a full interior van has a good distribution of weight for low traction conditions compared to a truck. If you have crap tires though, you'll have crap traction. Even if you have great tires, sometimes they're just no match for the conditions.

I live a few miles from a big hill that gets nasty when it is icy. I got to the top of the hill in my little VW with some good winter tires but the sheet ice was too much so I pulled into a turn out and waited for conditions to improve. I saw several big 4x4s slide into the ditch, a few Subarus lost it and hit the ditch too. The only car that had a command on the conditions was a Honda CRV with studded tires. Without chains or studs, no one was going anywhere.
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Old 01-06-2017, 05:58 PM   #3
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Originally Posted by zardac View Post
The Big Question:

Would placing the weight farther back, let's say six feet from the center of the rear wheels (on a hitch carrier) have a larger influence on traction than placement immediately above the rear wheels; as a result of the conservation of mass, the law of the lever, the momentum of fulcrums, or the original sin theory?
To your question:
Yes, yes, yes, and.....consult the bible?

Thinking of your situation in terms of basic physics (in particular of teeter-totters), by pushing the weight further rearward as you describe, you conceivably WILL be adding more "effective weight" to the rear wheels --- but this is only because you would be drawing weight OFF from the front wheels.

(The rear wheel is effectively acting as the "pivot point" in the middle of a teeter-totter, for this example.)

As you mentioned --- law of conservation of mass --- there's only so much total weight to go around. For example, if your van (and the "traction aiding weight" you are adding to increase traction) together weigh a total of 8000 pounds, you can't "create extra weight" simply by pushing the weight forward or backward, you can only redistribute the total weight in terms of how much is over each axle.

Given enough rear-mounted load (and rear-of-the-axle lever distance)......at a certain "theoretical tipping point" the front will actually start to lift.
Which might give you ultimate rear traction (you'd have all of the van's weight on the rear axle) but you sure couldn't steer or brake with any amount of control.

I would hazard that your best results would be obtained:
By having equal weight over front and rear axles (neutral handling characteristics) which would also still yield more than enough weight over the rear axle to get decent traction. None of these Sportsmobiles seem to be particularly lightweight.

To a good set of scales!
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Old 01-06-2017, 06:21 PM   #4
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Put weight right over the axle. That'll work fine. Further back shouldn't hurt or make the front tires much less grippy. The van has an 11' wheel base to start and the engine is directly over the front wheel.
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Old 01-06-2017, 06:51 PM   #5
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Maybe a good way to look at it is to split traction into 2 aspects. First- what most 'civilians' will think of (I am no 4wd expert, so that includes me) is getting moving. For that, yes, loading weight on the drive wheels if RWD (even at the expense of the steering front wheels), will get the most of the traction that the driving tires will afford.

Second part is handling / braking. For that, yes, balanced weight distribution would seem to give the best cornering, steering, and braking. I have seen many AWD / SUV drivers not understand the difference between these 2 aspects of driving on snow and ice. They know they can pull out of most any mess, and think proves that they have overcome the laws of physics. They now feel free to go sailing down the road at way too high a speed, and well, you can guess the rest..
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Old 01-06-2017, 08:04 PM   #6
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Also dont discount the easiest traction improve... Let some air out of your tires. even on ice it does wonders.
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Old 01-08-2017, 10:54 PM   #7
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Thanks for the responses.

I've got Nokian Hakka studded snow tires and they do a good job, but if I find an inexpensive way of noticeably improving snow and ice capability, I want to take advantage of it.

I spent a few years in snow country and enjoy driving in it if my vehicle is properly equipped.

In Portland snow is so rare that many (most) aren't prepared.

As a reasonably well prepared driver, I spend a couple of afternoons delivering loaves and fishes (meals) if we get snow that sticks around for awhile.
A lot of the old duffer regular drivers stay at home, and it's an easy excuse for me to squirrel around in the snow.

Sometimes the experience provides a warm glow.
Other times the experience reminds you that old people can be ******** too.
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Old 01-08-2017, 11:22 PM   #8
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Originally Posted by MountainBikeRoamer View Post
I would hazard that your best results would be obtained:
By having equal weight over front and rear axles (neutral handling characteristics) which would also still yield more than enough weight over the rear axle to get decent traction. None of these Sportsmobiles seem to be particularly lightweight.

To a good set of scales!
I recently stopped by the scales to find out about my weight distribution. Pre-4x4 conversion, I had 3,000 lbs on the front and 4,680 on the rear. I'll be stopping by the same scales for a follow up after I pick up my rig from QuadVan post-conversion.
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Old 01-09-2017, 06:17 PM   #9
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Quote:
Originally Posted by Glider View Post
I recently stopped by the scales to find out about my weight distribution. Pre-4x4 conversion, I had 3,000 lbs on the front and 4,680 on the rear. I'll be stopping by the same scales for a follow up after I pick up my rig from QuadVan post-conversion.
Thanks
This is good to know, and not what I expected.
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Old 01-09-2017, 06:47 PM   #10
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Quote:
Originally Posted by Glider View Post
I recently stopped by the scales to find out about my weight distribution. Pre-4x4 conversion, I had 3,000 lbs on the front and 4,680 on the rear. I'll be stopping by the same scales for a follow up after I pick up my rig from QuadVan post-conversion.
Seems like they may have reversed the front/rear numbers. I would never expect the front to be lighter than the rear, but I could be wrong.


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