Hanging weight, high or low?

So low and out front... I'm hoping to build my bracket in the near future. I don't have any rulebooks. Anyone know DHRA's rules on how far out?
 
PTPULLINCHASSIS said:
The Lower The Better.....
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Ok, I was hoping no one would mention that. Let me stop what will come of that post RIGHT NOW.

If your weights hit the scale at an NADM pull, they will come off the front and go in the bed.:banned:

Ive been to too many pulls, where the scales are beat to death by pullers who do not know how to build a weight rack.

As long as we are on that subject, the proper way to get on a scale is low lock 1st gear 4x4, and idle up on, and slow off.

The scale is a precision piece of equipment, not the Baja 1000.
 
Kman9090 said:
Guy around here hangs his like this. Never seen the advantage in it but I don't know?
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Thats the best you can get. Hes getting the most leverage he can thats for sure. I just couldnt spend the time making something like that and trusting it. I already has one weight bracket drop 1400 lbs on my foot this year. I dont need em falling from that far. Ive got a couple different ones. One the weights hang sideways in 4 rows to get as much weight out front as I can. The other is just a regular ole' bracket.
 
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zstroken said:
Too a certain extent. If you put the center of gravity of the weights below your center of gravity of your vehicle, any forward acceleration will result in a force being applied in the downward direction. Above the CG and any forward acceleration will result in a lifting force.
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agreed, below the COG can have some influence due to acceleration.
 
PTPULLINCHASSIS said:
The Lower The Better....it Takes More Force To Lift Any Given Amount Of Counter Weight That Is Lower In Relationship To The Pivot Point Of Your Chassis And Requires Less Force The Higher The Counter Weight Is Above The Pivot Point. Basicaly The Lower It Is The More Leverage It Gives You.
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I kinda see where you are going, but this is basic statics.

zstroken already stated it, lower is only effective when the vehicle is accelerating. Once up to speed, the height of the weight has no influence.

For example:

Pulling truck has a COG 2' above the ground, 1000 pounds of hanging weight is 5 feet in front of the axle centerline and 1 foot below the COG.

The truck accelerates to 20 MPH in 150 feet (assuming constant acceleration yeilds 2.9 feet per second per second)


Taking into account the moments applied by the accelerating mass, hanging that 1000 pounds 1 foot below the COG and 5 feet in front of the axle centerline will result in an additional 18 pounds of force applies to the front axle ONLY DURING ACCELERATION.
 
That bracket runs the weights sideways 2 deep, for a total of 1,600 pounds, just trying to get the weight as far out as possible. Only problem is 8,500 classes the truck with 1,600 pounds is 7,850 give or take. Yes that truck was at Oak Grove last year and I believe we talked to you Dan while lining up t 12:15 a.m. Had you just reciently moved to Mo? Oh and it does take a lot of renforcing, it had pulled threads off of bolts and other stuff trying to get it sturdy.
 
Diesel Freak said:
I kinda see where you are going, but this is basic statics.

zstroken already stated it, lower is only effective when the vehicle is accelerating. Once up to speed, the height of the weight has no influence.

For example:

Pulling truck has a COG 2' above the ground, 1000 pounds of hanging weight is 5 feet in front of the axle centerline and 1 foot below the COG.

The truck accelerates to 20 MPH in 150 feet (assuming constant acceleration yeilds 2.9 feet per second per second)


Taking into account the moments applied by the accelerating mass, hanging that 1000 pounds 1 foot below the COG and 5 feet in front of the axle centerline will result in an additional 18 pounds of force applies to the front axle ONLY DURING ACCELERATION.
Click to expand...

Got some math to back this up?
 
Jerrod picture it, or draw it out. If the weight was right in line with all of the acceleration would be straight backwards. If it is slightly below, most of it will be backwards, but using some trig you can see that some of the force will push down on it.
 
smokingoat04 said:
That bracket runs the weights sideways 2 deep, for a total of 1,600 pounds, just trying to get the weight as far out as possible. Only problem is 8,500 classes the truck with 1,600 pounds is 7,850 give or take. Yes that truck was at Oak Grove last year and I believe we talked to you Dan while lining up t 12:15 a.m. Had you just reciently moved to Mo? Oh and it does take a lot of renforcing, it had pulled threads off of bolts and other stuff trying to get it sturdy.
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Yea, that was me. You should have been there this year. I think it was 1:30 when we left!
 
Dan I don't know about your truck but mine will develop a rake to it when I hang my weight. I intend this weight to keep the front end of the truck down. I don't see how its going to add to the acceleration. Maybe we need a picture I will get started on paint.
 
If you were drag racing the truck without a sled trying to pick your front end off the ground, that would make sense.

However, when pulling Diesels that have TQ such as the Cummins, you need most weight left front, down low(without dragging on the scale!!).

Watch a video from the front- 800#(example) holds left side down, until the TQ is applied, then it comes up even.

You want to keep the front end on the ground, but you also use the weight to keep even traction on both front wheels.

The trig acceleration, why I do not doubt it is true, would be minuscule and really not important in sled pulling.
 
JerrodGlover said:
Dan I don't know about your truck but mine will develop a rake to it when I hang my weight. I intend this weight to keep the front end of the truck down. I don't see how its going to add to the acceleration. Maybe we need a picture I will get started on paint.
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It won't add to the acceleration. Acceleration of the truck, will try to accel the weights, if they are below COG, they will exert a force down.
 
IMO weight shold be centered correct, u only raise the DF when leaving the line but on the big end u want equal traction.................
So does it matter at the height or not?
Brandon
 
Sledpuller said:
If you were drag racing the truck without a sled trying to pick your front end off the ground, that would make sense.

However, when pulling Diesels that have TQ such as the Cummins, you need most weight left front, down low(without dragging on the scale!!).

Watch a video from the front- 800#(example) holds left side down, until the TQ is applied, then it comes up even.

You want to keep the front end on the ground, but you also use the weight to keep even traction on both front wheels.

The trig acceleration, why I do not doubt it is true, would be minuscule and really not important in sled pulling.
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Won't argue that it isn't much, but 18 lbs, is 18 lbs. When it comes down to 2 decimal places will decide the winner. I am betting the 18lbs would make a difference. The interesting point would be as the sled slams you to a stop, the weights below COG will have a tendency to lift the front end by the same amount, if you are accelerating and decelerating at the same rates
 
My DF will have a tendency to raise the whole way down the track. I put about an extra 150lbs off to the driveside. Figure between that and my frame in drivers seat, it should help.
 
Diesel Freak said:
I kinda see where you are going, but this is basic statics.

zstroken already stated it, lower is only effective when the vehicle is accelerating. Once up to speed, the height of the weight has no influence.

For example:

Pulling truck has a COG 2' above the ground, 1000 pounds of hanging weight is 5 feet in front of the axle centerline and 1 foot below the COG.

The truck accelerates to 20 MPH in 150 feet (assuming constant acceleration yeilds 2.9 feet per second per second)


Taking into account the moments applied by the accelerating mass, hanging that 1000 pounds 1 foot below the COG and 5 feet in front of the axle centerline will result in an additional 18 pounds of force applies to the front axle ONLY DURING ACCELERATION.
Click to expand...

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.
 
Sledpuller said:
Ok, I was hoping no one would mention that. Let me stop what will come of that post RIGHT NOW.

If your weights hit the scale at an NADM pull, they will come off the front and go in the bed.:banned:

Ive been to too many pulls, where the scales are beat to death by pullers who do not know how to build a weight rack.

As long as we are on that subject, the proper way to get on a scale is low lock 1st gear 4x4, and idle up on, and slow off.

The scale is a precision piece of equipment, not the Baja 1000.
Click to expand...

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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