Another weight question

Francesca Knowles wrote:
Tongue would be truck-on-scale-with-trailer-hitched-weight (no trailer wheels on scale) minus actual weight of the truck alone.

You also need to specify that the "truck-on-scale-with-trailer-hitched-weight" must be obtained with no load on the WD bars (i.e. no load transfer).

Ron

Nick, welcome to Open Roads Forum.

You've obtained an excellent set of scales data.
The minor inconsistency between the 15120# GCW and the 15080# GCW can be resolved by adjusting the 4860# RGAW to 4840# and adjusting the 5580# trailer axle load to 5560#.
That makes both GCWs equal to 15080#.

After the adjustment, the WDH is seen to add 160# to the trailer axles, add 320# to the steer axle, and remove 480# from the drive axle -- a textbook 1:2:3 relationship.

The correct way to estimate tongue weight is to subtract the unhitched TV GVW from the hitched with no WD applied TV GVW.
This gives tongue weight = 9680-8620 = 1060#.
The trailer weight is 15080-8620 = 6460#.
Tongue weight percentage is 1060/6460 = 16.4%. (Not uncommon to see a TH with a TW% greater than 15%.)

NOTE: Tongue weight cannot be calculated using drive axle loads only. You must include the steer axle loads also.

Application of tongue weight caused 440# to be removed from the steer axle.
Loading the WD bars caused 320# to be returned to the steer axle (after making the 20# adjustment in the steer axle load).
The Front Axle Load Restoration (FALR) is 320/440 = 73%.
For your 2013 F-250, Ford says that a FALR of 50% is sufficient.

Since your WDH with existing bars is capable of restoring more steer axle load than Ford specifies, I see no reason to switch to higher-rated bars.

Ron

:S

Dang! Of course that's right. My apologies both to you and the fella that tried to correct my bad math earlier!

Tongue would be truck-on-scale-with-trailer-hitched-weight (no trailer wheels on scale) minus actual weight of the truck alone.

This is what I thought at first too. Then I noticed the truck lost about 440 lbs from the front axle (bare truck vs truck with trailer and no spring bars). I guess due to the truck pitching back that weight was also transferred to the rear axle? So the actual weight due to the tongue would be around 1060#?

lbrjet wrote:


That is just plain wrong. The 400+ pounds move off of the front axle to the rear axle is not tongue weight.

Correct me if I'm wrong, but as I understand it tongue weight is the dead weight of the tongue at the ball BEFORE the application of the wd system.

If that's correct, the difference between the rear axle weight before/after hitching (and without w/d applied) should be a pretty close measure.

Francesca Knowles wrote:

omigosh wrote:



Is it (drive axle with spring bars untensioned- drive axle of just the truck)? 5160-3660= 1500#

Assuming the truck payload is exactly the same before/after the hitched-up number, that one is probably closest without actually weighing the tongue. Shocking, eh?

That is just plain wrong. The 400+ pounds move off of the front axle to the rear axle is not tongue weight.

The second one. 1060-1080 tongue weight.

If you have an Equal-i-zer 4 point then no, you can't just upgrade the bars. The bars and sockets have a larger diameter. You may be able to get new bars along with new sockets. Give Progress and a call and ask them.

omigosh wrote:



Is it (drive axle with spring bars untensioned- drive axle of just the truck)? 5160-3660= 1500#

Assuming the truck payload is exactly the same before/after the hitched-up number, that one is probably closest without actually weighing the tongue. Shocking, eh?

Tongue weight is determined by dropping the trailer with the tongue on the scales. You might be able to make some assumptions by subtracting truck only weight from
M truck hitched weight. Assuming everything else is the same.