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10-29-2014, 09:39 AM
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#21
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by HowieE
It is not my theory, I yield to Archimedes. He figured it out long before the WD hitch.
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Howie.
My records show that your Airstream should have 4000 pound axles with 12 inch bakes.
Andy
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10-29-2014, 08:40 PM
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#22
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by Ron Gratz
It really doesn't matter whether a "1/3,1/3,1/3" distribution is possible.
What does matter is -- adding a load equal to 1/3 of tongue weight to the front axle significantly increases the tendency for oversteer which can lead to loss of control.
Ron
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In practice or theory?
Andy
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11-05-2014, 09:30 AM
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#23
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Vintage Kin
Fort Worth
, Texas
Join Date: Nov 2006
Posts: 8,014
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(From earlier thread)
Connected with weight distribution:
Yukon front 3160,
rear 5160
TT 9140
Connected without weight distribution:
Yukon front 2840
rear 5440
TT 9180
Disconnected:
Yukon front 3720,
rear 3600
[Ron Gratz Chart]
Weighing #1 -- TT attached and Weight Distribution Activated
Let Front Axle Load be "FA1" 3160
Let Rear Axle Load be "RA1" 5160
Let TT Axles Load be "TT1" 9140
Then, while in same position on scales, take
Weighing #2 -- TT attached and Weight Distribution Not Activated (WD bars unloaded, but hanging in place)
Let Front Axle Load be "FA2" 2840
Let Rear Axle Load be "RA2" 5440
Let TT Axles Load be "TT2" 9180
Then, drive off scales and drop TT. Return to scales and take
Weighing #3 -- TV only -- TT Not Attached
Let Front Axle Load be "FA3" 3720
Let Rear Axle Load be "RA3" 3600
From the above values, you can calculate:
TV weight = FA3 + RA3 7320
Gross Combined Weight = (FA1 + RA1 + TT1)
{should also be equal to (FA2 + RA2 + TT2) if scale weights are correct}
17,460 & 17,460
TT Weight = Gross Combined Weight - TV Weight
10,140
Tongue Weight = (FA2 + RA2) - (FA3 + RA3)
8280 - 7320 = 960
Load Transferred to TT Axles
when WD System is Activated = TT1 - TT2 40
Something is off somewhere (TW, mainly. 12% of 10,140 is 1215-lbs as example). Were the readings all done at the same time?
.
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11-05-2014, 11:01 AM
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#24
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Rivet Master
2014 27' FB Eddie Bauer
Chelsea
, Michigan
Join Date: May 2010
Posts: 1,792
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Wow, 1,700 lbs. hitch weight!
I would imagine that the suspension on any tow vehicle capable of safely handling that amount of hitch weight (while leaving sufficient payload capacity for the cargo and the spouse) would have such a stiff suspension that moving some of the hitch weight forward with a conventional WD hitch would be a real challenge.
Our Airstream has about half that hitch weight, and I have a 2015 Ford-F-250 with the crew cab and long bed and our 1,200 Reese bars are barely adequate to move sufficient weight to the front wheels.
__________________
Bob Martel
WBCCI# 5766
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11-05-2014, 11:05 AM
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#25
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Rivet Master
2005 39' Land Yacht 390 XL 396
Common Sense
, Texas
Join Date: Sep 2007
Posts: 5,319
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Quote:
Originally Posted by AnnArborBob
Wow, 1,700 lbs. hitch weight!
I would imagine that the suspension on any tow vehicle capable of safely handling that amount of hitch weight (while leaving sufficient payload capacity for the cargo and the spouse) would have such a stiff suspension that moving some of the hitch weight forward with a conventional WD hitch would be a real challenge.
Our Airstream has about half that hitch weight, and I have a 2015 Ford-F-250 with the crew cab and long bed and our 1,200 Reese bars are barely adequate to move sufficient weight to the front wheels.
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Actually, the longer the wheelbase of the tow vehicle, the more difficult it is for the weight distribution hitch to return the weight to the front axle, and conversely, the shorter the wheelbase of the TV, the easier it is.
Your F250 has one of the longest wheelbases of the popular tow vehicles.
__________________
Regards,
Steve
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11-05-2014, 11:23 AM
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#26
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Rivet Master
2014 27' FB Eddie Bauer
Chelsea
, Michigan
Join Date: May 2010
Posts: 1,792
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Thanks, Steve. That is exactly what Andy Thompson said when he set up our hitch. But I still like towing with the long wheelbase vehicle, smooth as a baby's behind! But the real reason we have the long bed is to accommodate two road bikes and two mountain bikes along with some typical camping gear.
I still can't get over the OP's 1,700 tongue weight!
What is a "six cylinder sludge burner?" Surely your 2500 has a V-8? Did you get it neutered?
__________________
Bob Martel
WBCCI# 5766
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11-05-2014, 11:34 AM
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#27
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Rivet Master
2005 39' Land Yacht 390 XL 396
Common Sense
, Texas
Join Date: Sep 2007
Posts: 5,319
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My 2500 is a Dodge Ram with the I6 6.7L Diesel.
Yes, that 1,700 pounds sounds a little high as my '34 SO is only around 1200lbs measured on a Sherline. I too have a hard time getting the front axle load returned to unhitched weight with 1200 pound bars, or let's say it's all I want to lift getting the bars onto the Reese SC hitch. But, I like the simplicity and performance of the hitch.
As you probably know, there is one person active on this forum who would advocate that I use 600lb bars, or some such BS, but I think he makes at least part of his living selling hitches and bars.
The thing is, 1200lbs is just as difficult to distribute properly behind a 2500 as behind a Cadillac, and maybe even more difficult because of the wheelbase. 1200lbs is 1200lbs, a fact.
__________________
Regards,
Steve
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11-05-2014, 11:43 AM
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#28
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Vintage Kin
Fort Worth
, Texas
Join Date: Nov 2006
Posts: 8,014
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The scale figures show 960-lb TW
Sent from my iPhone using Airstream Forums
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11-05-2014, 11:45 AM
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#29
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Rivet Master
1991 34' Excella
Princeton
, New Jersey
Join Date: Aug 2003
Posts: 7,070
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Quote:
Originally Posted by Inland RV Center, In
Howie.
My records show that your Airstream should have 4000 pound axles with 12 inch bakes.
Andy
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Sorry Andy your records are incorrect. The trailer was manufactured with 2,800 lbs axles and the ones I replaced, and bought from you, are 3,200 lbs.
By definition Pivot point, the center point of any rotational system There can only be one pivot point within a system. You can choose to select a different point while evaluation a mechanical system, but can only be working with one at a time. The force to maintain the system in equilibrium about a given point will still be the sum of the force times distance. Again it is a mathematical impossibility to reach the so called 1/3, 1/3, 1/3 relationship unless the combination was specifically designed with that in mind. Highly unlikely when dealing with so many variables involved here.
The pivot point we should be focused on here is the rear axle of the TV. A WD hitch is employed to reduce some of the trailer tongue load off that axle by transferring weight to the other axles, TV front and trailer. One should accept that the distances between the TV rear axle and the TV front axle and the trailer axles is not likely to be the same. Given that you should see that the above ratio is impossible to accomplish.
Now lets get away from 40 year old urban myths and deal with today's reality.
__________________
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles
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11-05-2014, 12:00 PM
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#30
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by HowieE
Sorry Andy your records are incorrect. The trailer was manufactured with 2,800 lbs axles and the one I replaced, and bought from you, are 3,200 lbs.
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That's correct for a 34 foot trailer.
The 31 foot Excella's use the 4000 pound axles.
Andy
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11-11-2014, 09:11 AM
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#31
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Vintage Kin
Fort Worth
, Texas
Join Date: Nov 2006
Posts: 8,014
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Best Weight Distribution hitch?
Quote:
Originally Posted by pjtaia
Question for those of you towing 34' Airstreams: What is the best weight distribution hitch to handle the 1,700 lb. hitch weight on my 2002 34' with slide? Is it unrealistic to expect a WD hitch to actually distribute the weight equally between the front and rear axles (along with a little to the trailer...)? Sway control is also a factor, but without proper weight distribution it is a moot point...
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Sway control with a PP or HA is not dependent on WD.
Depending on the TV the amount of front axle weight restoration varies according to TV manufacturers instructions.
According to your scale tickets the TW is approximately 1000-lbs or ten percent which is not unusual on a 34 (assuming the scale tickets were ask recorded the same day and same way). I would still expect it to be around 1200. Is the TT level when hitched ?
On an HA it is difficult to preload the hitch without an adjustable stinger or to cut and re weld stinger. Somewhere between 50-100% FALR is the likely target.
Sent from my iPhone using Airstream Forums
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