What Does a Weight-Distributing Hitch Do? - Page 2 - Fiberglass RV


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 02-25-2007, 03:10 PM   #15
Senior Member
 
Trailer: Casita 17 ft Spirit Deluxe
Posts: 509
All I can say is that experience with 5 different vehicles and three different trailers with and without WDH has led me to the conclusion that, "Its all in the weights."

I am sure that your 7,000 lb. Excursion tows differently than my 6,000 lb. Escalade. Just as my 1750 lb. travel trailer I towed with a 2,300 lb. Covair Coupe.

However, as an engineer and a mathmatician I have a great deal more faith in actuals than I do in expert witness testimony. In other words, "Get it weighed!" It is the only way to know for sure.
__________________

__________________
CD and Joyce Smith - Lily, Violet, and Rose
1999 Casita 17' SD - "The Little Egg"
2007 Escalade - 6.2L V8 - 6L80E Trans - 3.42 Diff
CD Smith is offline   Reply With Quote
Old 02-25-2007, 03:27 PM   #16
Senior Member
 
Name: Per
Trailer: 2000 Burro 17 ft Widebody towed by Touareg TDI
Oregon
Posts: 863
Registry
Roger:

I think your point about the 17' Casita may illustrate the issue pretty well. Whenever I've read the tongue weight of that particular trailer it seem to be in the 400 to 450 lb range (correct me if I'm wrong). I suppose it is possible that they had to put the axle a few inches further back than would be the average for similar trailers.

That would definitely change my thinking, since the Honda's tow weight limit is 350 lbs. Therefore my airbags would not do the job and only a WDH would. At 290 lbs tongue weight for the Burro I want to keep it right there over the rear wheels for stability. To quote: "It's all in the weights."
__________________

__________________
Per Walthinsen is offline   Reply With Quote
Old 02-25-2007, 03:46 PM   #17
Senior Member
 
Name: Darwin
Trailer: 2002 19 ft Scamp 19 ft 5th Wheel
Posts: 3,030
Send a message via Yahoo to Darwin Maring
It needs to be mentioned that there are different levels of equalizer bars.
You should not need 1 thousand pound bars.

Roger: Is it possible to use just one bar?

Concerning sway: Consider a friction sway control.
__________________
Darwin Maring is offline   Reply With Quote
Old 02-25-2007, 06:05 PM   #18
Senior Member
 
Pete Dumbleton's Avatar
 
Trailer: Scamp
Posts: 3,072
Send a message via Yahoo to Pete Dumbleton
I don't know how the auto-leveling system on the Escalade works, but if all it does is jack up the rear end (like air bags or helper springs do), it is NOT transferring any appreciable weight from the rear axle to the front axle -- Prove it by putting a load in the back of it, get to a set of scales with front/rear split, note the readings with system on, turn it off and note the new reading on the front axle... The leveling system is leveling the body, not the suspension.

That said, however, I believe the system should be OFF when setting up the WDH because proper setup calls for measuring the front/rear distance to the ground and keeping that ratio when the hitch is adjusted (in other words, the weight transferred to the TV should be spread evenly between the axles to make it 'sink' on an even keel) -- Hard to do if the system is constantly adjusting itself.

Any WDH system WILL transfer some of the weight from the rear of the tow vehicle to the trailer axle, and how much goes to front axle vs trailer axle will depend on the ratio of the ball-to-axle distances... Picture the extreme of the adjustment being set so high that the rear wheels are off the ground (like the old advertisement) -- The trailer axle is clearly supporting more than the trailer!

Easiest illustration I can think of is a conventional longbow with the ends on a table and the handgrip horizontal to the table but up in the air; the shorter the string, the higher the center will be off the table. The spring bars and chains are the string and the hitch ball is the handle, with the front and trailer axles becoming the bow ends.
__________________
Pete Dumbleton is offline   Reply With Quote
Old 02-25-2007, 06:18 PM   #19
Senior Member
 
Roger H's Avatar
 
Name: Roger
Trailer: Y2K6 Born Free 32RQ on the Kodiak chassis, 1995 Coachmen 19' B-van and 1996 Precision 21' Sailboat
Iowa
Posts: 5,000
An interesting point is that most hitches that are rated at 1,000 lb tongue weight and 10,000 lbs towing are only rated that highly using WDH systems; otherwise they're limited to 500 lbs and 5,000 lbs dead weight.

Per, as CD says, it's all in the weights... if you have noticeable sag in the rear end of your tow vehicle, even though the tongue weight is within the capacity of the vehicle, then you'd probably benefit from weight distribution.

Darwin, Reese (and perhaps others now) make a single-bar WDH system just for trailers with a lighter tongue weight. Gina just ordered one. In the Reese world, the load bars come in a wide array of weights, and you need to have the appropriate set of bars for your application.

Roger
__________________
Roger H is offline   Reply With Quote
Old 02-25-2007, 06:25 PM   #20
Senior Member
 
Pete Dumbleton's Avatar
 
Trailer: Scamp
Posts: 3,072
Send a message via Yahoo to Pete Dumbleton
Quote:
That would definitely change my thinking, since the Honda's tow weight limit is 350 lbs. Therefore my airbags would not do the job and only a WDH would. At 290 lbs tongue weight for the Burro I want to keep it right there over the rear wheels for stability. To quote: "It's all in the weights."
Per, if you read the literature carefully, or call the various tech supports, you will find that adding air bags (really air springs) or adding helper/overload springs or jamming 2x4s between the rear axle and the body WILL NOT change the tongue weight load restriction of the tow vehicle.

Also included in that trailer TW load restriction may be any inside or roof weight that touches to the rear of the axle -- Read your owner's manual carefully about this.
__________________
Pete Dumbleton is offline   Reply With Quote
Old 02-25-2007, 06:42 PM   #21
Senior Member
 
Brian B-P's Avatar
 
Name: Brian
Trailer: Boler (B1700RGH) 1979
Alberta
Posts: 5,000
Pete, you're right that the tongue weight restriction is not changed by spring changes, such as air bags. That, presumably, is exactly why Per said that he would need to go to a WD system if the trailer's tongue weight were higher. I think Per meant to indicate that the Odyssey's weight carrying limit is 350 lb, but the limit is higher with WD (that is the case for my Sienna, with the same 350 lb limit value).

This is an important point: adding springs helps the rear axle handle the load it is carrying, but does not change the factory limit, or the load carried by each axle. A WD system does change the loads carried by all three axles, reducing the rear axle load while increasing the others.

By the way, I call the Firestone Coil-Rite units (like the similar AirLifts) air "bags" because in our case they are just bags added to the coils; they are not standalone air springs. They do function as air springs in parallel to the coil springs.
__________________
1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WD
Information is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.
STATUS: No longer active in forum.
Brian B-P is offline   Reply With Quote
Old 02-25-2007, 06:46 PM   #22
Senior Member
 
Brian B-P's Avatar
 
Name: Brian
Trailer: Boler (B1700RGH) 1979
Alberta
Posts: 5,000
Quote:
An interesting point is that most hitches that are rated at 1,000 lb tongue weight and 10,000 lbs towing are only rated that highly using WDH systems; otherwise they're limited to 500 lbs and 5,000 lbs dead weight...
Yes, I agree that this is true. With the WD system in effect, the rear-most attachment points of the hitch receiver frame to the vehicle structure are not under nearly as much load (they may actually be pushing up instead of pulling down on the vehicle), so structurally it is not surprising that the hitch and/or the vehicle will have a higher WD than weight-carrying limit.

I don't think this has anything to do with vehicle control, just structure, as indicated by the fact that these are limits established by the hitch manufacturer.
__________________
1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WD
Information is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.
STATUS: No longer active in forum.
Brian B-P is offline   Reply With Quote
Old 02-25-2007, 06:54 PM   #23
Senior Member
 
Brian B-P's Avatar
 
Name: Brian
Trailer: Boler (B1700RGH) 1979
Alberta
Posts: 5,000
Steve, an interesting and valuable perspective, as always.

Quote:
...The WDH does not magically transfer trailer axle weight to the Tug. It only transfers some tongue weight from the Tug's rear axle to the Tug's front axle...
... and some load from the Tug's rear axle to the Trailer's axle!

I know that may throw more fuel on the fire here, but consider this: the WD system is used because of the effect of tongue weight on the tow vehicle, but the way it works has nothing to do with tongue weight. You can crank up those spring bars enough to counteract the nose-up tilt of the tug, or less, or more (yes, CD Smith, we know this is bad), or whatever you want until something breaks or the rear wheels come off the ground - even if there was zero tongue weight to start with. The amount of load it is able to transfer is not limited or affected by the trailer's actual weight distribution.

The WD system changes the distribution of [b]load, but doesn't move any [b]mass anywhere, and therefore it can't (nor can any technology known to science) make the weight happen anywhere other than where the mass is. The tongue weight stays where it always was, on the hitch ball. It's just a matter of which tires support the whole mess.
__________________
1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WD
Information is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.
STATUS: No longer active in forum.
Brian B-P is offline   Reply With Quote
Old 02-25-2007, 07:01 PM   #24
Senior Member
 
Brian B-P's Avatar
 
Name: Brian
Trailer: Boler (B1700RGH) 1979
Alberta
Posts: 5,000
Quote:
It needs to be mentioned that there are different levels of equalizer bars.
You should not need 1 thousand pound bars.

Roger: Is it possible to use just one bar?
Ack! No! (But Roger should answer, too...)
The single-bar design runs the bar down the middle. If you used only one bar of a two-bar WD system on it's original bracket, you would always be pulling the trailer over to one side, and applying a significant upward force and torque to the hitch off centre. This has to be bad.

I wholeheartedly agree that "thousand pound" bars are completely unsuitable. The idea of the differently rated bars is just that the higher rated ones are stiffer, and can be used to apply greater force and thus transfer more load. A bar which is too stiff means that as the combination goes over humps or through dips and changes angle, the force will change too much, to potentially damaging levels.

One of the reasons to use a suitably-sized WD hitch is to avoid excessive weight of metal to haul around... but the other would be to get softer spring bars, to better suit the purpose. Bigger is certainly not always better.
__________________
1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WD
Information is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.
STATUS: No longer active in forum.
Brian B-P is offline   Reply With Quote
Old 02-25-2007, 07:16 PM   #25
Senior Member
 
Brian B-P's Avatar
 
Name: Brian
Trailer: Boler (B1700RGH) 1979
Alberta
Posts: 5,000
I think all of us who have been active in this discussion and who have adjustable suspensions (CD's self-leveling Escalade, Per and I with air bags) understand that suspension adjustment does not change how much load each axle carries.

Quote:
...That said, however, I believe the system should be OFF when setting up the WDH because proper setup calls for measuring the front/rear distance to the ground and keeping that ratio when the hitch is adjusted (in other words, the weight transferred to the TV should be spread evenly between the axles to make it 'sink' on an even keel) -- Hard to do if the system is constantly adjusting itself....
If you are using [b]ride height to adjust a WD hitch, then certainly the self-leveling needs to be off.

I think the problem is that this method is fundamentally flawed. Making the tug sink evenly does not ensure that the load is spread evenly among the axles (if that were even desirable, but that's another subject), because the front and rear spring rates are normally different. If it sinks one inch on each end, that might be twice as much increase in front axle load as rear... or half.

Is the target is really a specific preference for load distribution? That is what I think CD, Roger, and Pete are all saying... and I agree.

Then the only way to get there is to use a scale. You can scale the whole rig (with self-leveling turned on or airbags adjusted) at various WD tension settings until the balance is right, or you can do the math and then use a tension scale on the WD spring bar chain (confirming afterwards by measuring the axle loads), but in the end, ride height won't tell you what your WD system really did, unless you do something extreme (and bad) like putting a rear axle with no spring adjustment right back where it was with no trailer.
__________________
1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WD
Information is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.
STATUS: No longer active in forum.
Brian B-P is offline   Reply With Quote
Old 02-25-2007, 07:29 PM   #26
Senior Member
 
Brian B-P's Avatar
 
Name: Brian
Trailer: Boler (B1700RGH) 1979
Alberta
Posts: 5,000
Quote:
... recognize that a weight distributing hitch and the function of sway control are completely separate functions, sometimes combined into the same piece of equipment (Reese Dual-Cam) and sometimes two (or three on large trailers) pieces, the weight distributing hitch with load bars and the friction sway control devices.
Ideally, this might be the case. The single bar design (from any of the Cequent companies, such as Reese) gets the closest, and I'm not saying that's necessarily good...

All of the two-bar designs (which is every other design on the market) have some additional effects, beyond the load transfer from rear axle to the other axles. Since they have a bar on each side, interesting things happen when the coupling pivots in any direction:

If the trailer [b]rolls a different amount from the tug, one side pulls down harder than the other on the trailer frame, tending to make the trailer follow the tug. This means badly controlled trailer roll is somewhat controlled by the tug, maybe reducing sway.... and if you don't want this coupling, you've got it anyway.

If the trailer [b]pitches relative to the tug, the bars tighten (nose-down pitch) or loosen, tending to keep the two aligned even though it means changing axle load distribution. That's how a too-stiff WD system between a massive tug and delicate trailer could be destructive.

If the trailer [b]yaws (either a normal turn, or wanders off-line when the tug is going straight) the spring bars are moved forward on one side and back on the other side (relative to the trailer frame), so the chains are no longer vertical and tend to pull the trailer towards straight. Since undesired "sway" is usually yaw, this might be good... but it also resists turning when you want (or need) to.

There is also friction (at the spring bar trunnions or other pivoting mounts) resisting any movement in the yaw direction.

While a friction-type link "bar" is a separate device, all of the other "sway control" features are accidents of the two-bar design, or deliberate exaggerations of them.
__________________
1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WD
Information is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.
STATUS: No longer active in forum.
Brian B-P is offline   Reply With Quote
Old 02-25-2007, 07:32 PM   #27
Senior Member
 
Trailer: 2007 17 ft Casita Spirit Deluxe
Posts: 183
"I'm not sure in your case whether a WDH would be useful or not, but from seeing how a Casita 17 drops the rear of an Odyssey"

I checked the specs on an 2007, Odyssey. While it states it can tow 3500 lbs, it only has a tongue weight rating of 350 lbs. If you have a 17' SD fully loaded, the tongue weight is more than that. So, the Odyssey would be exceeding it's capabilities. If the manufacturer does not offer a towing package which would extend it capabilities, then I suspect exceeding it's listed specifications is not warranted by the manufacturer.

"It's not AS necessary with my Tundra, I can tow without it, but the handling is much improved using it."

It's interesting that a full size Toyota Tundra (assuming it's one of the V8 engines) that has a towing capacity between 8,500 - 10,000 lbs. would have any engineering problems towing a 17' fiberglass trailer weighing one third to one half of it's towing capacity.
__________________
Gary Lynch is offline   Reply With Quote
Old 02-25-2007, 09:11 PM   #28
Moderator
 
Frederick L. Simson's Avatar
 
Name: Frederick
Trailer: Fiber Stream
California
Posts: 8,151
Registry
Send a message via AIM to Frederick L. Simson
Thumbs down

Quote:
(unless Honda says specifically not to use one).
Quite the contrary!
<div align="center">ODYSSEY
2003 Owner's Manual</div>
Quote:
[b]Towing Equipment and Accessories
Weight Distributing Hitch
If the total trailer weight is more than 1,850 Lbs (840 Kg), you must also use a weight distributing hitch. This device transfers weight from the vehicle's rear wheels to the front wheels, and to the trailer's wheels. Carefully follow the hitch maker's instructions for proper installation and adjustment.

[b]Sway Control
If the total trailer weight exceeds 2,000 Lbs (900 Kg), you should install a sway control device to minimize swaying that can occur in crosswinds and in normal and emergency driving maneuvers. Your trailer maker can tell you what kind of sway control you need and how to install it.

[b]Trailer Brakes
Honda recommends that any trailer having a total weight of 1,000 Lbs (450 Kg) or more be equipped with its own electric or surge-type brakes.
I interpreted the above to mean that the towing capacity of the Honda Odyssey is:
1,000 Lbs (450 Kg) without Trailer Brakes
1,850 Lbs (840 Kg) without Weight Distributing Hitch
2,000 Lbs (900 Kg) without Sway Control
3,500 Lbs (1,580 Kg) with [b]all of the above but only [b]2 occupants.

__________________

__________________
Frederick - The Scaleman
1978 Fiber Stream 16 named "Eggstasy" & 1971 Compact Jr. named "Boomerang"
Frederick L. Simson is offline   Reply With Quote
Reply

Tags
weighing, weight


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
weight distributing hitch--clearance Derek Johnson Towing, Hitching, Axles and Running Gear 7 05-13-2008 07:53 PM
Weight Distributing hitch & sway Bar Terrance Classified Archives 0 02-02-2006 04:49 PM
weight distributing hitch Legacy Posts Towing, Hitching, Axles and Running Gear 18 02-26-2003 06:36 PM
weight distributing hitch--clearance Derek Johnson Problem Solving | Owners Helping Owners 0 12-31-1969 07:00 PM

» Upcoming Events
No events scheduled in
the next 465 days.
» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 01:01 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.