Hanging weight, high or low?

PTPULLINCHASSIS said:
ARE WE DRAG RACING OR TRUCK PULLING????? CAUSE I THINK YOU ARE LEAVING OUT THE MAIN CONTRIBUTING FACTOR IN THE EQUATION.......THE 30,000LB SLED THATS STRAPPED TO YOUR AZZ TRANSFERING MORE WEIGHT TO THE REAR OF YOU TRUCK THE FARTHER DOWN THE TRACK YOU GO. IN PULLING LEVERAGE PLAYS A MUCH BIGGER PART THAN THE ACCELERATION AFFECTS ON WEIGHT PLACEMENT.
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He never said you can't have leverage.
 
I agree with placing more on the driver side to equal out traction, I've seen on open differentials the driver side spin out time and time again, with weight placed in the center. With weight placed to the driver side it's a toss up, depending on the placement, to much, or to little, but what about the trucks that have lockers, or welded diffs. in the front?
 
smokingoat04 said:
..... but what about the trucks that have lockers, or welded diffs. in the front?
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You need to even it out even more. Why? Because you do not want a locked axle having less traction on one side. Damage could result.
 
PTPULLINCHASSIS said:
SORRY SLEDDY I FORGOT TO MENTION I HINGE MY WEIGHT BOXES SO THEY CAN PIVOT UP AND ALSO INSTALL ROLLERS OR WHEELS ON THE BOTTOM OF THE BOX. BUT WHAT DO I KNOW I'M ONE OF THOSE OLD SCHOOL GASSER ROOTS PULLERS:hehe:
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Roger that, hope some rookies take that advice.

Dont get me started on gassers, or your 1" reverse rake!!!!:bang:hehe:
 
PTPULLINCHASSIS said:
ARE WE DRAG RACING OR TRUCK PULLING????? CAUSE I THINK YOU ARE LEAVING OUT THE MAIN CONTRIBUTING FACTOR IN THE EQUATION.......THE 30,000LB SLED THATS STRAPPED TO YOUR AZZ TRANSFERING MORE WEIGHT TO THE REAR OF YOU TRUCK THE FARTHER DOWN THE TRACK YOU GO. IN PULLING LEVERAGE PLAYS A MUCH BIGGER PART THAN THE ACCELERATION AFFECTS ON WEIGHT PLACEMENT.
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Actually there is no difference with regards to weight transfer between drag racing and sled pulling other than the dead weight of the sled and the friction between the ground and pan.

While the sled will pull down on the back of the truck, whatever load in placed on the rear axle will be removed from the front....obviously adjusted for the moment arms. It's just basic statics with some dynamics tossed in when the vehicle is changing velocity. As the speeds are very low, dynamics plays a minor part. Which is why vertical positioning of weight plays a minor part..but that minor part could be the difference in winning or loosing

I will post a free body diagram and some math later.

oh, does anyone know the coefficient of friction of steel on dirt?
 
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here ya go.

Adding the sled to the mix won't be that hard...just need to know the weight of the sled, the speed of weight transfer to the skid, and the coefficient of friction between the skid and the dirt.
 

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I like the weight just high enough to get the truck on and off the trailer.And clear the scales.Rolers are fine but if they still it the scales hard enough still scews them up some times.

Dale
 
Diesel Freak said:
here ya go.

Adding the sled to the mix won't be that hard...just need to know the weight of the sled, the speed of weight transfer to the skid, and the coefficient of friction between the skid and the dirt.
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Somebody that knows how to read that:

Tell me what the hell is going on in that diagram please?
 
I can't explain the graph but

From my understanding that the high the center of gravity(cog) a vehicle has the more weight it wants to transfer. so if I have a truck that weighs in at 7500 and say has a cog of 45"s if I can hang a 1000lbs below the cog then I would think it would lower the cog and make it so that the truck doesn't want to transfer as much weight. witch would keep more force on the front tires.
 
Ok my brother is having a hard time understanding this but he doesn't seem to see it as he is in the truck. His truck has air lockers and it pulls up on the drivers side the whole way down the track. He needs to build a different weight bracket for next year in order to hang more weight and to get some weight on that drivers side tire. Now as for my truck I have tried hanging the weights on the drivers side and in the middle. For me it seems like my truck sits down better with the weight in the middle. Don't ask me why maybe it's the 3rd gen frames but it seem like the 2nd gens like the weight hanging off to the drivers side and the 3rd gen guys usually hang it in the midddle or maybe it's just me that's noticed this?? Here is a picture of my brothers truck lifting the right front the whole way down the track. Best way to tell your set up really is have somebody with a really good camera taking action shots.
 

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It even depend if you have the rear sus,blocked solid and the way you have your bars mounted if there at a big angle or if they are almost flat and how long they are.I prefor to have them go from the rear cornor of the front door to center of the axle and make the braket to have the bars pushing forward not at a angle so they aren't pushing upward. so your not trying to lift the frontend.

Dale
 
Kman9090 said:
Ok my brother is having a hard time understanding this but he doesn't seem to see it as he is in the truck. His truck has air lockers and it pulls up on the drivers side the whole way down the track. He needs to build a different weight bracket for next year in order to hang more weight and to get some weight on that drivers side tire. Now as for my truck I have tried hanging the weights on the drivers side and in the middle. For me it seems like my truck sits down better with the weight in the middle. Don't ask me why maybe it's the 3rd gen frames but it seem like the 2nd gens like the weight hanging off to the drivers side and the 3rd gen guys usually hang it in the midddle or maybe it's just me that's noticed this?? Here is a picture of my brothers truck lifting the right front the whole way down the track. Best way to tell your set up really is have somebody with a really good camera taking action shots.
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Third gen frames are stronger, you could be on to something there. They don't flex nearly as much.
 
roachie said:
Somebody that knows how to read that:

Tell me what the hell is going on in that diagram please?
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Unfortunately, if you haven't taken a college-level statics class, you'll never totally understand what he's doing there.

Short story, a free body diagram is a way to calculate forces based on some known forces and geometry. The 3 main laws are, all the up and down forces must sum to zero; the horizontal forces must sum to zero, and all the moments must sum to zero. So you set up those equations and plug in what you know, and then you can calc many of the forces you don't know.

People use the term "leverage" so willy-nilly these days that it's almost useless (especially when applied to traction bars). A correct FBD is the only way to figure out what's really happening. Each configuration of truck would have its own diagram since the geometry of each really does make a difference.

If you can pick up a good college text on Statics, that'd be whatcha need.
 
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