Ram Cummins/Aisin Failures

fj12ryder wrote:

Grit dog wrote:
Y’all have to remember as well that a basic moment diagram assuming fully moment resistant or completely free frictionless connections or pivot points will only get you close on weights.
Minor nuances that would require dynamics and even finite element analysis to get an “exact” answer may or will change the numbers…..a little bit.
So y’all can continue to worry about or argue about where “the extra 50lbs” or whatever went. But the principles are sound and now the discussion has gone into the weeds due to those who are proud they know where the decimal place should be and have weighed their rigs a time ‘er 2 and have some theories bouncing around in their beans that are of little real world significance.

Or to put it in layman’s terms. Dually trucks were designed primarily to carry heavy loads. That was and still is the primary goal of having training wheels.
Do ya think that every dually pickup ever made, with the skinny little front tires and axles/springs that don’t have much reserve capacity, would still be the norm if loads in the truck bed (pin weights or cow poops) put a significant load on the front axles?
The answer is a resounding NO.
A Texas front bumper likely puts as much or more weight on the front of any truck than the vast majority of stinger steered trailers out there.

Or, again, in a quick sentence, 12V is speaking the truth here whether y’all want to argue about nomenclatures or wheelbases or not.

Such erudition, and done in a manner that manages to offend almost everyone. You have to admire such talent. :)

YES, he is a great equal opportunity offender. :B

Marty said: "The percentage amount 12V is talking about, or the formula used for ball mounts, works to a point."

YES 100% agree, it gets you CLOSE.

Grit said: "12V is speaking the truth here whether y’all want to argue about nomenclatures or wheelbases or not."

:B:B:B

Grit dog wrote:
Y’all have to remember as well that a basic moment diagram assuming fully moment resistant or completely free frictionless connections or pivot points will only get you close on weights.
Minor nuances that would require dynamics and even finite element analysis to get an “exact” answer may or will change the numbers…..a little bit.
So y’all can continue to worry about or argue about where “the extra 50lbs” or whatever went. But the principles are sound and now the discussion has gone into the weeds due to those who are proud they know where the decimal place should be and have weighed their rigs a time ‘er 2 and have some theories bouncing around in their beans that are of little real world significance.

Or to put it in layman’s terms. Dually trucks were designed primarily to carry heavy loads. That was and still is the primary goal of having training wheels.
Do ya think that every dually pickup ever made, with the skinny little front tires and axles/springs that don’t have much reserve capacity, would still be the norm if loads in the truck bed (pin weights or cow poops) put a significant load on the front axles?
The answer is a resounding NO.
A Texas front bumper likely puts as much or more weight on the front of any truck than the vast majority of stinger steered trailers out there.

Or, again, in a quick sentence, 12V is speaking the truth here whether y’all want to argue about nomenclatures or wheelbases or not.

Such erudition, and done in a manner that manages to offend almost everyone. You have to admire such talent. :)

Even the formula spouted by one person for ball mounts, was like a clock, but only correct once in a range of 1-1500 lbs of HW.
Reason, a pickup starts tail high! so you pull less weight off of the front initially. BUT, as you go with more weight, the tail drops, and you pull more weight off the front as your hitch weight increases! To a point you might be pulling 1-2 lbs off the front, for every lb or 100 lbs of weight you add.
My Navistar for instance, only has 60-100 lbs off the front, with 1500 lbs added to the rear. His formula said some 300-400 lbs. 1500 on a 16500 RA that takes some 5-6000 lbs before the springs even think about compressing.
Meanwhile my 96 CC, when I had the stock 6400 lbs springs, I took about 400 lbs off the front. When I installed 8400 lbs springs, it dropped to 250-300 lbs. Same as my 8500 lb rear spring 05 DW CC GM.
The percentage amount 12V is talking about, or the formula used for ball mounts, works to a point. BUT< one needs to remember that many other factors need to be included as to what is or may be the final number if you are going to depend on math alone!
But, either formula, you need to take into account, spring capacity, softness, wheel base, where the pin/hitch weight is centered vs RA. When you can add a factor to the formula for these issues, you can come closer with math.

Marty

Y’all have to remember as well that a basic moment diagram assuming fully moment resistant or completely free frictionless connections or pivot points will only get you close on weights.
Minor nuances that would require dynamics and even finite element analysis to get an “exact” answer may or will change the numbers…..a little bit.
So y’all can continue to worry about or argue about where “the extra 50lbs” or whatever went. But the principles are sound and now the discussion has gone into the weeds due to those who are proud they know where the decimal place should be and have weighed their rigs a time ‘er 2 and have some theories bouncing around in their beans that are of little real world significance.

Or to put it in layman’s terms. Dually trucks were designed primarily to carry heavy loads. That was and still is the primary goal of having training wheels.
Do ya think that every dually pickup ever made, with the skinny little front tires and axles/springs that don’t have much reserve capacity, would still be the norm if loads in the truck bed (pin weights or cow poops) put a significant load on the front axles?
The answer is a resounding NO.
A Texas front bumper likely puts as much or more weight on the front of any truck than the vast majority of stinger steered trailers out there.

Or, again, in a quick sentence, 12V is speaking the truth here whether y’all want to argue about nomenclatures or wheelbases or not.

I was shocked when I first saw how little weight goes to the front axle. Then someone explained thew math formula above and then it made total sense.

fj12, a double trip thru the scales would be interesting.

Cummins12V98 wrote:

fj12ryder wrote:

Cummins12V98 wrote:
It's very easy math to figure your weight transfer to the front axle. Measure centerline rear axle to centerline front axle. Now how much forward is centerline of kingpin or gooseneck ball from centerline rear axle.

My axle to axle centerline is 170" and forward dimension of kingpin is 4" that is .0235% of 170". My pin weight is 6,000#. .0235% of 6,000# is 141#.

Whoops, your math is off a bit. :) 4" is actually 2.35%. That seems low to me too, mine is about the same amount in front of the rear axle and it puts over 200 lbs. on the front axle, and that's with a hitch weight of about 3400 lbs. Don't know about the math, but that's according to the Cat Scale. :)

4 Divided by 170 is .0235 so it depends on how you are doing the math. Take 6000. X 2.35 the number is wrong. Take 6000. X .0235 and it is 141#.

I have to ask, did you go thru the scales then unhook and go right thru again?

Just going by the math rules: 2.35% is .0235.

I've never unhooked and gone back through, but I've weighed 3 times loaded, and once unloaded, and the numbers are about the same every time. A little over 200 lbs. with a 3,400 lb. hitch weight. Our old trailer with 3,000 lb. hitch weight added over 400 lbs. to the front, but it was the quad cab Dodge, so shorter wheelbase. I'll have to look at the Cat scale receipts when we get back home for exact numbers.

12v is correct here, whether he put a % sign on it without moving the decimal or not.
Math doesn’t lie. And the difference between 141 and 200 lbs is, well, you’re not comparing the same setups.
And that’s not appreciable anyway. Be like saying you have increased front end wear if your fat buddy is riding shotgun vs your supermodel wife….
Yes there are some dynamic forces that increase, particularly during braking, which is a very small % of overall drive time.
But the fact remains, if your pin is centered over the rear axle, it’s not putting any weight up front.

However, carry on. It’s great entertainment to watch people make mountains out of a small pile of c rap.

fj12ryder wrote:

Cummins12V98 wrote:
It's very easy math to figure your weight transfer to the front axle. Measure centerline rear axle to centerline front axle. Now how much forward is centerline of kingpin or gooseneck ball from centerline rear axle.

My axle to axle centerline is 170" and forward dimension of kingpin is 4" that is .0235% of 170". My pin weight is 6,000#. .0235% of 6,000# is 141#.

Whoops, your math is off a bit. :) 4" is actually 2.35%. That seems low to me too, mine is about the same amount in front of the rear axle and it puts over 200 lbs. on the front axle, and that's with a hitch weight of about 3400 lbs. Don't know about the math, but that's according to the Cat Scale. :)

4 Divided by 170 is .0235 so it depends on how you are doing the math. Take 6000. X 2.35 the number is wrong. Take 6000. X .0235 and it is 141#.

I have to ask, did you go thru the scales then unhook and go right thru again?