Measuring Weight Distribution on Hitch

[dznf0g]

Originally Posted by Ephraim

I would love to see these equations. Being somewhat of a nerd, my curiosity is peaked.

I think I'm beginning to get a handle on things now. Next time I load up, I need to allot some scale time to make multiple passes over the scale so I can develop a chart of forces. The hope is that in the future, I can make a double pass over the scales. On the way to the storage lot, I'll measure the loaded, unhitched truck and then after hitching up, make a reweigh of the hitched noWD truck/Airstream. then using the chart, know exactly how to set the jacks for that trip.

I have thought about providing the sheet, but:

It is so complicated and drilled to the minutia that:

1) I would have to write a substantial manual in order for anyone else to make sense of it

2) It is pretty personalized to my AS, TV and gear loading/weights.

3) I would be lambasted and criticized for my level of detail and they would say, " just hitch up and go camping." It's happened before, several times and it hurts my fragile feelings.

I do this stuff to keep my brain active and feed my technical toy addiction. I gotta know how everything works. And I hate crosswords and sudoku. They have no end purpose for real world applications.

[rmkrum]

Welcome to the ranks of the “Overkill Engineering Department! You are pointing out some of my deepest quirks. Are you sure we’re not related? (Grin)

[dznf0g]

Originally Posted by rmkrum

Welcome to the ranks of the “Overkill Engineering Department! You are pointing out some of my deepest quirks. Are you sure we’re not related? (Grin)

Oh, I've been over in the corner cube of that department for decades. They only let me out for food and potty breaks.

Sent from my SM-G950U using Airstream Forums mobile app

[rmkrum]

Sounds all too familiar. I used to really believe ‘Dilbert’ was a documentary and Scott Adams was actually spying on me to get material…even my kids call me ‘The world’s oldest geek’!

[guskmg]

Always set up your hitch with the airbags switched off. Then, after you get everything level and even, switch on the airbags. Otherwise you will not get anywhere near the correct adjustments. I have been doing this with a full airbag suspension system for nearly 12 years and it works good with no front end separation.
guskmg

[uncle_bob]

Originally Posted by Ephraim

The 6" was just to put some WD so I could get some weight measurements. I've yet to figure out how much I need or want. I had been adjusting to get rid of the porpoising I was experiencing, but then I replaced the shocks and that went away completely. ........

Hi

WD has next to nothing to do with porpoising. Indeed porpoising is very road dependent. Trying to fix it often only works on this road, but not that one....

Bob

[chuckbye]

I am extremely frustrated with the weights and especially the W/D.
Traveled 7000 miles with new 25 ft Globetrotter and 2020 GMC Sierra
crew with 900# passengers and 100# in pickup.

I have a propride trailer hitch and can not transfer a reasonable amount of W/D to steer axle. AS trailer 5800#, front axle 3100# and rear axle 4800# with 940# tongue weight and 1400# sway control bars as recommended by propride driven at 9.5 inches. 3800# rear axle and drive axle 3700#. max. rating. 5.3 L gas. What to do? Thanks.

[dznf0g]

Originally Posted by chuckbye

I am extremely frustrated with the weights and especially the W/D.
Traveled 7000 miles with new 25 ft Globetrotter and 2020 GMC Sierra
crew with 900# passengers and 100# in pickup.

I have a propride trailer hitch and can not transfer a reasonable amount of W/D to steer axle. AS trailer 5800#, front axle 3100# and rear axle 4800# with 940# tongue weight and 1400# sway control bars as recommended by propride driven at 9.5 inches. 3800# rear axle and drive axle 3700#. max. rating. 5.3 L gas. What to do? Thanks.

How many washers do you have in the head tilt in the stinger? I have no problem with weight transfer with a 2015 chevy 1500 maxtow.

[ROBERT CROSS]

Originally Posted by chuckbye

I am extremely frustrated with the weights and especially the W/D.
Traveled 7000 miles with new 25 ft Globetrotter and 2020 GMC Sierra
crew with 900# passengers and 100# in pickup.

I have a propride trailer hitch and can not transfer a reasonable amount of W/D to steer axle. AS trailer 5800#, front axle 3100# and rear axle 4800# with 940# tongue weight and 1400# sway control bars as recommended by propride driven at 9.5 inches. 3800# rear axle and drive axle 3700#. max. rating. 5.3 L gas. What to do? Thanks.

Do you have CAT tickets?
At least 3

Loaded for camping weights for the TV.
Weight of rig no weight distribution.
Weight with WD set.

Originally Posted by uncle_bob

Hi

WD has next to nothing to do with porpoising. Indeed porpoising is very road dependent. Trying to fix it often only works on this road, but not that one....

Bob

Really?...I have experienced it whenever the front axle is too light.
Roads, we have no control over WD we do.

Bob
🇺🇸

“I’m not an expert, I’m just a loose association of thought.”
RLC

[Ephraim]

Originally Posted by guskmg

Always set up your hitch with the airbags switched off. Then, after you get everything level and even, switch on the airbags. Otherwise you will not get anywhere near the correct adjustments. I have been doing this with a full airbag suspension system for nearly 12 years and it works good with no front end separation.
guskmg

I'm sorry, but that makes no sense whatsoever.

The air bags and WDH perform different functions, but they do interact. If you set up your WDH and then auto level, you just moved your WD.

It makes more sense to let the auto level put the level where it needs to be and then use CAT scales (or similar) to set the WD allowing the auto level to do it's thing.

[jcl]

Originally Posted by uncle_bob

Hi

WD has next to nothing to do with porpoising. Indeed porpoising is very road dependent. Trying to fix it often only works on this road, but not that one....

Bob

Porpoising is initiated by road undulations. The solution is more damping in the system. That can come from improved TV shocks, or more WD, or both.

[ROBERT CROSS]

Originally Posted by jcl

Porpoising is initiated by road undulations. The solution is more damping in the system. That can come from improved TV shocks, or more WD, or both.

Explain then please, no undulations and ours goes way with proper WD.

Roads are not the ONLY cause.

Please know of what you speak😂.



Bob
🇺🇸

[jcl]

Originally Posted by ROBERT CROSS

Explain then please, no undulations and ours goes way with proper WD.

Roads are not the ONLY cause.
\
Please know of what you speak��.

Bob
����

Exactly as it should.

If the roads are undulating, that can set up a harmonic with the combination, causing porpoising. It can be initiated by a bump in the road. A very smooth road is less likely to initiate it.

The goal is to damp out the harmonic. With sufficient damping in the system, or combination, a disturbance will die out, and not continue. With shock absorbers, if they are working and you bounce the vehicle, the motion dies out. With weak shocks, it continues.

With a heavy hitch load, more damping can be required, often beyond the capability of the tow vehicle shocks alone. Properly set WD provides that additional damping in the vertical plane.

I think we actually agree.

[ROBERT CROSS]

Originally Posted by jcl

Exactly as it should.

If the roads are undulating, that can set up a harmonic with the combination, causing porpoising. It can be initiated by a bump in the road. A very smooth road is less likely to initiate it.

The goal is to damp out the harmonic. With sufficient damping in the system, or combination, a disturbance will die out, and not continue. With shock absorbers, if they are working and you bounce the vehicle, the motion dies out. With weak shocks, it continues.

With a heavy hitch load, more damping can be required, often beyond the capability of the tow vehicle shocks alone. Properly set WD provides that additional damping in the vertical plane.

I think we actually agree.

YEP...we do. More than one cause, the roads we can't fix proper, WD we can.

Bob
🇺🇸

[jcl]

Originally Posted by ROBERT CROSS

YEP...we do. More than one cause, the roads we can't fix proper, WD we can.

Bob
🇺🇸

Exactly.

[dznf0g]

sometimes I think that some folks on here mis-think porpoising. (first, I agree with Bob and JCL, so don't misunderstand my post)

I wonder if a lot of folks try and WD-out all repetitive motion. IOW, my search for the least amount of WD (to protect AS) possible to accomplish the proper weight transfer results in a sweet spot whereby, over a single undulation in the road, I get the rebound of a solo vehicle, lightly laden. So, I get a compression, a rebound, and a smaller compression and a settling back to "neutral"...of the rear suspension.

Heavily laden, this scenario does result in more amplitude of the motions, and I wonder if some folks call this porpoising, and WD-it-out, resulting in too much WD application.

I think I have been applying moderately too much WD frequently. I don't have front end separation yet, but I see evidence of "issues". When I have a lot of WD applied, I see a bowing out of the front center skin about 5" above the lower rub rail.

When I was removing my front battery box door frames, had all fasteners removed, and just some sealer adhering the frame....as I worked the frame loose (not a lot of pull) a crack appeared in the skin running diagonally up and toward the center of the panel. I am of the belief that the skin has work hardened and become brittle with the flexing, over time. I drilled the end and made my patches larger....but I have a feeling it is just a matter of time before I need to install a hold down plate and new center skin.

Think there is any validity to all this?

[ROBERT CROSS]

Originally Posted by dznf0g

sometimes I think that some folks on here mis-think porpoising. (first, I agree with Bob and JCL, so don't misunderstand my post)

I wonder if a lot of folks try and WD-out all repetitive motion. IOW, my search for the least amount of WD (to protect AS) possible to accomplish the proper weight transfer results in a sweet spot whereby, over a single undulation in the road, I get the rebound of a solo vehicle, lightly laden. So, I get a compression, a rebound, and a smaller compression and a settling back to "neutral"...of the rear suspension.

Heavily laden, this scenario does result in more amplitude of the motions, and I wonder if some folks call this porpoising, and WD-it-out, resulting in too much WD application.

I think I have been applying moderately too much WD frequently. I don't have front end separation yet, but I see evidence of "issues". When I have a lot of WD applied, I see a bowing out of the front center skin about 5" above the lower rub rail.

When I was removing my front battery box door frames, had all fasteners removed, and just some sealer adhering the frame....as I worked the frame loose (not a lot of pull) a crack appeared in the skin running diagonally up and toward the center of the panel. I am of the belief that the skin has work hardened and become brittle with the flexing, over time. I drilled the end and made my patches larger....but I have a feeling it is just a matter of time before I need to install a hold down plate and new center skin.

Think there is any validity to all this?

A big yes...it took two Seasons for me to realize that the 1400lb bars were much too stiff and the poorly designed receiver needed to go.
Once the lash-up was correct the ride for both AS & TV improved dramatically.

Bob
🇺🇸

[dznf0g]

Originally Posted by ROBERT CROSS

A big yes...it took two Seasons for me to realize that the 1400lb bars were much too stiff and the poorly designed receiver needed to go.
Once the lash-up was correct the ride for both AS & TV improved dramatically.

Bob
🇺🇸

I have never used 1400# bars....or 1200 for that matter. From my early day's learnings here, and of ownership, I knew there were certain "fragilities" surrounding ASes. I used 800# bars on my reese. They work fine, but they are at the very top of their ability to transfer weight. I used 1k bars on the Hensley and now the PP. I do wonder if I should have gotten 900# bars.....hmmm.

[jcl]

Originally Posted by ROBERT CROSS

A big yes...it took two Seasons for me to realize that the 1400lb bars were much too stiff and the poorly designed receiver needed to go.
Once the lash-up was correct the ride for both AS & TV improved dramatically.

Bob
����

Yes here too.

Bob, I always enjoy seeing your before and after pictures of the stock and aftermarket receiver. They make a very strong point.

I think of them when we discuss towing with SUVs and other non HD pickups, and the suggestion is made to reinforce the receiver. Many posters believe that the stock receiver defines the full vehicle maximum capability.

I also think of them when people with a 250/2500 or greater say it is impossible to get any substantial FALR. Often they need to be reminded that addressing a flexible receiver should be the first step.

[dznf0g]

I was a GM factory rep during that round receiver period that Robert pictures. Big changes happened after that.

The receivers became square, more robust, and the labels mysteriously read the same (or within 100# of the actual vehicle's tow rating on which they were installed.

For example for my truck year, all 1500s have the same hardware, but a base truck might list 9900/990 max on the receiver. My maxtow truck lists 1200 max w/WD, (on a 11,900 max Trailer Weight truck) making the receiver in the class V category, albeit in the lower part of ClassV.

Disclaimer!!!! this in no way implies you can hitch up more than the max for which the entire truck was built!