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Old 07-26-2020, 10:30 PM   #21
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No, Automotive engineers, the Society members and others will all agree with the technical accuracy of the statement. Some will advise that excessive under steer is advised for novice drivers as sliding into a guard rail at .3 g in their opinion is safer than experiencing over steer at a much faster or more severe .5-.6 g. Me, I like the idea of being able to avoid sliding into the adjacent lane or the rail and safely making a .45 g avoidance swerve so I will optimize my steering response, increase sway stability and improve comfort with the appropriate WD tension.
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Old 07-27-2020, 03:29 AM   #22
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No, Automotive engineers, the Society members and others will all agree with the technical accuracy of the statement. Some will advise that excessive under steer is advised for novice drivers as sliding into a guard rail at .3 g in their opinion is safer than experiencing over steer at a much faster or more severe .5-.6 g. Me, I like the idea of being able to avoid sliding into the adjacent lane or the rail and safely making a .45 g avoidance swerve so I will optimize my steering response, increase sway stability and improve comfort with the appropriate WD tension.
Positioning a load of 500 lbs to 1200lbs 4 ft + behind the rear axle of the TV alone will remove most Understeer built in to most vehicles. The WD hitch only removes more. This loading condition is what makes a towing combination different than a single vehicle situation you are using to defend yourself.
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Old 07-27-2020, 06:47 AM   #23
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To answer the original question, reducing 140 lb. on the front axle is acceptable. I used the same hitch up until 2 weeks ago, with both a 2012 GMC with Duramax and a 2002 GMC with a Duramax. In both cases the front axle had about 150-210 less weight on the front axle and made no real difference. The Duramax is heavy enough to compensate for the small decrease. Adjust till it feels right and tows good. Some on this forum say a WD hitch is not necessary, and you really won't know till you need it. The Husky has the sway control built in and works well, with my past 6 years of towing with it. If I had not been given a Hensley for free, I would still be using and enjoying the Husky. I am keeping the Husky until I am fully satisfied with the Hensley. Use your hitch, and know that you have a very good sway control and WD hitch. I don't get into all the technical stuff, but know what works and what doesn't. The Husky works, and works well!!!
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Old 07-29-2020, 05:17 PM   #24
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Positioning a load of 500 lbs to 1200lbs 4 ft + behind the rear axle of the TV alone will remove most Understeer built in to most vehicles. The WD hitch only removes more. This loading condition is what makes a towing combination different than a single vehicle situation you are using to defend yourself.
False, unless one includes all vehicles ever designed in the set. if one include only vehicles equipped with a factory installed hitch and designed for 500+ it would be less than 5%. If one included only those designed for 1200+ it would be 0%.
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Old 07-30-2020, 03:17 AM   #25
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False, unless one includes all vehicles ever designed in the set. if one include only vehicles equipped with a factory installed hitch and designed for 500+ it would be less than 5%. If one included only those designed for 1200+ it would be 0%.
The intention was to cover the ratings range so yes if the vehicle is rated at 700 TW adding 500lbs TW will cause a large shift just as one rated to 1300lbs and you add 1200lbs. I should have known since you confuse easily on the topic. Bottom line is any vehicle will handle a higher lateral acceleration with 50% FALR than with 100% regardless of how much TW rating is used. End of story.
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Old 07-31-2020, 07:59 PM   #26
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Wrong, all vehicles with sever under steer will handle a higher lateral acceleration with 100% FALR. At 50% FALR these vehicles will slide out of the corner and thus will have a lower cornering speed relative to the same vehicle at 100% FALR.
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Old 08-01-2020, 05:34 AM   #27
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Wrong, all vehicles with sever under steer will handle a higher lateral acceleration with 100% FALR. At 50% FALR these vehicles will slide out of the corner and thus will have a lower cornering speed relative to the same vehicle at 100% FALR.
Caution! Most advice given here is nothing more than a subjective opinion. Please reference the vehicles owner manual for instruction on towing and hitch use which is based on physics, facts, and research.
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Old 08-01-2020, 06:18 AM   #28
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Profxd, please provide the physics and/or formulas and data that demonstrates my error. No, I know you won't.

Fact: Manufacturers, test their vehicles and provide guidance for the worst case, which is max towing capacity.

Fact: Heavy trailers have much larger moments of inertia, the physical basis for the towing forces contributing to rear axle tire slip and thus over steer.

Fact: Returning load to the front axle, also increases over steer tendency

Fact: A vehicle will negotiate any given corner fastest and most stably at zero under steer gradient.

Corollary: Therefore as trailer weight is reduced from max, under steer increases. To maintain the manufactures intended towing under steer gradient, and thus maximum intended cornering performance, one would have to increase FALR, or take other more onerous and unadvised steps.

Conclusion: With lower trailer weights, more FALR is required for optimal cornering performance.
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Old 08-01-2020, 02:54 PM   #29
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“Conclusion: With lower trailer weights, more FALR is required for optimal cornering performance.”

Caution! This advice given here is nothing more than a subjective opinion. Please reference the vehicles owner manual for instruction on towing and hitch use which is based on physics, facts, and research.
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Old 08-01-2020, 03:24 PM   #30
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Positioning a load of 500 lbs to 1200lbs 4 ft + behind the rear axle of the TV alone will remove most Understeer built in to most vehicles. The WD hitch only removes more. This loading condition is what makes a towing combination different than a single vehicle situation you are using to defend yourself.
I hesitate to get into this furrball, but I don't understand the above statement.

A 500-1200 lb. load behind the rear axle acts to unload the FRONT axle. A WDH applies an upward force to the rear of the TV, which serves to ADD load to that front axle and remove it from the rear axle. ...or at least that's what I've always believed.

So it seems "The WD hitch only removes more." is incorrect.

Would someone educate me?
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Old 08-01-2020, 03:25 PM   #31
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Originally Posted by Profxd View Post
“Conclusion: With lower trailer weights, more FALR is required for optimal cornering performance.”

Caution! This advice given here is nothing more than a subjective opinion. Please reference the vehicles owner manual for instruction on towing and hitch use which is based on physics, facts, and research.
Owners manuals provide fantastic worst case guidance but they make for poor physics and mechanical engineering handbooks. By applying proper kinetic sciences, the conclusion follows quite elegantly and naturally. Perhaps you might circle the erroneous statement and provide the correct physical principle.
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Old 08-01-2020, 04:05 PM   #32
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I hesitate to get into this furrball, but I don't understand the above statement.

A 500-1200 lb. load behind the rear axle acts to unload the FRONT axle. A WDH applies an upward force to the rear of the TV, which serves to ADD load to that front axle and remove it from the rear axle. ...or at least that's what I've always believed.

So it seems "The WD hitch only removes more." is incorrect.

Would someone educate me?
Nice catch Bob, the statement is indeed incorrect as you surmised, but not so much for the part you extracted. The primary error is the part that claims adding a load to a hitch 4 feet behind the rear axle will reduce understeer, it will not, the load (presumably from tongue weight) alone shifts weight from and raises the front axle as you indicate so it increases (adds to) under steer tendency. What Profxd failed to accurately describe is that along with the helpful load, comes the much larger effect of the trailer inertial moment which induces significant lateral force on the rear axle in corners increasing rear tire slip angle for a net reduction in under steer because the lateral force overrides the vertical load effect previously described.

Addition of WD tension improves steering response and front tire cornering stiffness further reducing under steer tendency as profxd indicated. But he erred further when he left out the reality that vehicles designed for towing heavy loads are necessarily so biased with under steer, that as long as you're towing less than 75% of max rated towing capacity (for my vehicle that would be 12,750 lb and I'm pulling 7,200 lb) over steer is not an issue in even the worst circumstances. Over steer can become an issue for those near max towing capacity depending on the vehicle and the physical limits driving capacity.

Hoping this clears it up.
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Old 08-02-2020, 05:20 PM   #33
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“The primary error is the part that claims adding a load to a hitch 4 feet behind the rear axle will reduce understeer, it will not,“

Completely wrong again Brian. This absolutely will reduce Understeer!

Please see signature below.
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Old 08-02-2020, 05:41 PM   #34
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From a SAE professional engineer.
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Old 08-02-2020, 07:02 PM   #35
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“The primary error is the part that claims adding a load to a hitch 4 feet behind the rear axle will reduce understeer, it will not,“

Completely wrong again Brian. This absolutely will reduce Understeer!

Please see signature below.

Yeah I said that, but it is because of trailer inertia, not tongue weight please read my post again.
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Old 08-03-2020, 03:33 AM   #36
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Nice try but no. It’s the longitudinal position of the tongue mass applied to the TV that reduces Understeer (the change in loading condition). The WDH tension doesn’t change the longitudinal position of that mass, it reduces Understeer further by reducing TV rear tire cornering stiffness. Same mass amount and position with less TV rear tire cornering stiffness (tire grip) equals less Understeer or possibly neutral to oversteer. Nearly everything that improves sway damping will make the Understeer gradient worse. The best solution is find the ideal balance of tongue weight which maintains enough sway damping at highway speeds, yet light enough not to cause the loss of most Understeer. Since increased WDH tension reduces Understeer is use should be minimized. I can’t believe that you honestly think that you are correct and the whole automotive industry is wrong on this. It’s not up for debate, it’s a proven fact yet you continue to instruct others and give them incorrect information.
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Old 08-03-2020, 04:58 AM   #37
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I have the 800-1200lb bars.

Hitch installed by dealer back in November 2019 when we purchased the 2004 Classic. Seems to pull well behind my 2006 Chevy 2500HD Duramax.

Weighing included:
Full tank of Diesel plus 5 gal tank of diesel, Me, tools, solo stove, charcoal grill, charcoal, generator, gas, tent, chairs etc. (wife and dog were not with me 140 total).
Camper stocked plus 54 gals water in fresh tank.

Picture is of scale. The front axle gets 140lbs lighter when connected to the trailer. The rear axle increases by 840lbs.

I have not tried the measure fender well method as described in the manual for the hitch.

Should the front decrease any at all? Is this acceptable or do I need more tension on the bars?

Thanks
You are missing at least one ticket....I do a max run to checkk WD efficiency.

Notice ticket one FAW is 100lb less than ticket four FAW.

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BTW...the engineerefued is grinable.🤓
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Old 08-03-2020, 07:20 AM   #38
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Nice try but no. It’s the longitudinal position of the tongue mass
You mean tongue load. The mass of a typical Airstream tongue is less than 30 lb.

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applied to the TV that reduces Understeer (the change in loading condition).
Here is a thought experiment to better illustrate. Remove the trailer and place a device in the receiver that supports 1000 lbs of mass directly over the location previously supporting the trailer tongue. With that in place how has under steer gradient changed compared to unladen? To help you with this question consider the inertial moment of the 1000 lb mass compared to the inertial moment of 7000 lb of trailer. I agree that as the hitch distance is increased, eventually the lateral load inertia might overcome vertical axle load changes acting to increase front and decrease rear axle tire slip. But we are dealing with relatively short axle to ball distances. If this was what you were trying to describe, then I suppose we are just talking past each other.

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The WDH tension doesn’t change the longitudinal position of that mass, it reduces Understeer further by reducing TV rear tire cornering stiffness. Same mass amount and position with less TV rear tire cornering stiffness (tire grip) equals less Understeer or possibly neutral to oversteer.
We agree on this point.

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Nearly everything that improves sway damping will make the Understeer gradient worse. The best solution is find the ideal balance of tongue weight which maintains enough sway damping at highway speeds, yet light enough not to cause the loss of most Understeer. Since increased WDH tension reduces Understeer is use should be minimized.
If you change minimized to optimized, then we generally agree on this point also, though I would say the "everything" applies to WD tension since there are many sway damping methods that don't involve shifting load and don't alter steering response.

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I can’t believe that you honestly think that you are correct and the whole automotive industry is wrong on this. It’s not up for debate, it’s a proven fact yet you continue to instruct others and give them incorrect information.
I'm nearly certain I am in complete alignment and agreement with the automotive engineers. Perhaps sometimes I don't describe things as well as I should, but my advice is not in opposition to the industry, it supplements it. The OEM guidance generally applies to the worst case at max towing. My advice matches theirs exactly at max towing weight. I extend the guidance to the real world where people are pulling 25-75% of max weight.
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Old 08-05-2020, 11:26 AM   #39
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You mean tongue load. The mass of a typical Airstream tongue is less than 30 lb.


Here is a thought experiment to better illustrate. Remove the trailer and place a device in the receiver that supports 1000 lbs of mass directly over the location previously supporting the trailer tongue. With that in place how has under steer gradient changed compared to unladen? To help you with this question consider the inertial moment of the 1000 lb mass compared to the inertial moment of 7000 lb of trailer. I agree that as the hitch distance is increased, eventually the lateral load inertia might overcome vertical axle load changes acting to increase front and decrease rear axle tire slip. But we are dealing with relatively short axle to ball distances. If this was what you were trying to describe, then I suppose we are just talking past each other.


We agree on this point.


If you change minimized to optimized, then we generally agree on this point also, though I would say the "everything" applies to WD tension since there are many sway damping methods that don't involve shifting load and don't alter steering response.


I'm nearly certain I am in complete alignment and agreement with the automotive engineers. Perhaps sometimes I don't describe things as well as I should, but my advice is not in opposition to the industry, it supplements it. The OEM guidance generally applies to the worst case at max towing. My advice matches theirs exactly at max towing weight. I extend the guidance to the real world where people are pulling 25-75% of max weight.
The industry sets a FALR across the range of tongue weight where a WDH is needed, not just for the maximum rated. The same physics applies at lower tongue weights as it does at the maximum.

So you think that mounting 1000lbs 5ft behind the rear axle without a trailer doesn’t change and lower Understeer or affect handling very much? I know it does so why don’t you give it a try and let me know how it works out. In fact the Understeer Gradient is mostly dependent on the TV characteristics and tongue load. By the way the mass the trailer coupler carries is a percentage of the mass between the trailer axle centerline and the coupler. But you already know that. No minimized is the correct word not optimized.
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Old 08-06-2020, 07:22 AM   #40
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The industry sets a FALR across the range of tongue weight where a WDH is needed, not just for the maximum rated. The same physics applies at lower tongue weights as it does at the maximum.
How could you support this statement? Given that The conditions WD addresses are all variable depending on trailer inertia, tongue weight, trailer cornering stiffness, axle to tongue length and several other minor factors, how is it possible that one number fits all scenarios? Answer is it can't.

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So you think that mounting 1000lbs 5ft behind the rear axle without a trailer doesn’t change and lower Understeer or affect handling very much? I know it does so why don’t you give it a try and let me know how it works out. In fact the Understeer Gradient is mostly dependent on the TV characteristics and tongue load. By the way the mass the trailer coupler carries is a percentage of the mass between the trailer axle centerline and the coupler. But you already know that. No minimized is the correct word not optimized.
No, I know it does, which is why I asked the question. I wonder if you know HOW it changes or WHY it changes the way it does. Your statement of fact, that under steer is mostly dependent on tongue load, is misleading at best, though tongue weight is a reasonable proxy for trailer inertial moment, it is not the whole story.
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