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Old 03-29-2015, 12:39 PM   #1
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TV Weight Distribution

I have just returned from a short trip and before getting home got my weights from a CAT scale. I have a 19ft Bambi FC (all tanks empty) pulled by a 2011 F150 ecoboost. I have weight distribution and sway control. Here is the results of the weighing

Front Axle 3320 lbs
Rear Axle 3800 lbs
Trailer 3620 lbs

My question is this, should I attempt to transfer more weight to my front axle of the TV by adjusting my weight distribution set up. Any recommendations would be helpful.

Bruce
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Old 03-29-2015, 01:06 PM   #2
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It would be helpful to understand the truck axle weights without the trailer, the truck and trailer axle weights with the weight distribution not connected, and then the truck and trailer axle weights with the weight distribution adjusted.
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Old 03-29-2015, 01:13 PM   #3
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We need the before before we can comment on the after.
Go Back to the scales for the weights noted above.
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Old 03-30-2015, 10:36 AM   #4
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Quote:
Originally Posted by Brucethept View Post
My question is this, should I attempt to transfer more weight to my front axle of the TV by adjusting my weight distribution set up. Any recommendations would be helpful.
Bruce, the owners manual for your 2011 F-150 states:

Weight-distributing hitch
When hooking-up a trailer using a weight-distributing hitch, always use the following procedure:
1. Park the vehicle (without the trailer) on a level surface.
2. Measure the height of the top of the front wheel opening on the fender, this is H1.
3. Attach the trailer to the vehicle without the weight distributing bars connected.
4. Measure the height of the top of the front wheel opening on the fender a second time, this is H2.
5. Install and adjust the tension in the weight distributing bars so that the height of the front fender is approximately halfway between H1 and H2.
6. Check that the trailer is level. If not level, adjust the ball height accordingly and repeat Steps 3–6.


With your relatively light tongue weight, it might be difficult to obtain accurate changes in fender opening heights.

You also can adjust the WDH based on front axle load -- but you would need to return to the scales and measure axle loads for 1) TV only, 2) TT hitched with no WD applied, and 3) TT hitched with WD applied.
The WDH should be adjusted so the front axle load from 3) is approximately half way between the loads from 1) and 2).

Ron
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Old 03-30-2015, 11:24 AM   #5
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To increase the accuracy of your fender measurements put painters tape on the fender and mark each measurement with a line on the tape and record the measurement.

You want to see weight transferred to the front axle. Depending on your TV and front end type that will vary but 1/2 is a good starting point. You do not want to remove weight when the trailer is attached as that will changes the steering configuration and result is less steering control in general.
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Old 03-31-2015, 09:48 AM   #6
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You want to see weight transferred to the front axle. Depending on your TV and front end type that will vary but 1/2 is a good starting point. You do not want to remove weight when the trailer is attached as that will changes the steering configuration and result is less steering control in general.
According to Ford's revised WDH-adjustment specifications which have been in effect since circa 2010, you do want to have less weight on the front axle when towing.

For example, if the trailer's tongue weight causes 300# to be removed from the front axle when hitched without WD applied, the WDH should be adjusted to restore approximately 150# to the front.
That means, according to Ford's current specifications, for this example, the front end should be about 150# lighter when hitched with WD applied.

Ron
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Old 03-31-2015, 01:24 PM   #7
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There are far too many variables, length of trailer, wheel base of TV, front and rear spring type of the TV, front to rear weight ratio of the TV, front axle type of the TV, type of WD hitch used, in setting up a WD hitch to reduce it to a simple equation suggestion 50% as the ending consideration. Lawyers not engineers write such statements.

Historically this process has been plagued by such simplistic urban myths like 1/3 transferred to each axle set and returning a set % to the front axle weight. The first is mathematically impossibility given the dimensional and spring system variabilitys. The second is too simplistic and could not be applied equally to an I beam and A frame front axle.
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Old 04-01-2015, 09:28 AM   #8
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Some background information pertaining to changes in WDH-adjustment specifications made by TV and WDH manfacturers during the past five years can be found in this post.

Ron
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Old 04-01-2015, 09:53 AM   #9
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It all boils down to this definitive statement from General Motors.

Chevrolet/GMC says the FALR should be 100%, 50% or 0% depending on TV model and TT weight.

So much for that being helpful.

We still need your "before" scale weights of the TV axles and before and after fender measurements in order to comment on YOUR CASE effectively. Also what WD system are you using?
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Old 04-01-2015, 10:19 AM   #10
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Quote:
Originally Posted by HowieE View Post
It all boils down to this definitive statement from General Motors.

Chevrolet/GMC says the FALR should be 100%, 50% or 0% depending on TV model and TT weight.

So much for that being helpful.

...snip...

It's helpful in context - there are several complicated tables in the GM user guide that you navigate through to understand the correct FALR based on a myriad of possible configurations. It's their way of realizing one size doesn't fit all (as you've mentioned earlier) and providing the appropriate answer for each person's need so you don't have to guess. I think I've posted those tables elsewhere in the forums because I really do believe they are very helpful.
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Old 11-03-2017, 07:12 AM   #11
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I've got a somewhat similar question to the original poster, so I thought I'd add to this thread (if that's wrong, let me know; I'm new to Airstreaming and these great Forums).

I'm towing a 25' FC with a 2017 F150 (with towing package). I hit the scales a while back, and all weights look pretty good in terms of being safely within limits. The one question I have (like the original poster) is if my weight distribution over my TV axles is OK. Let me apologize up front for not getting a reading for my whole rig without weight distribution. I didn't know to get that as I hadn't found this Forum at that time. Anyway, here's what I do know:

TV alone:
Front axle 3300 lbs (max is listed at 3525)
Rear axle 2800 lbs (max is listed at 3800)

TV, TT, with weight distribution/sway control:
Front axle 3080 lbs
Rear axle 3500 lbs

So, the weight distribution is doing what it's supposed to do, but I guess I'm wondering if I should be at all concerned that the loaded axle weights are not a 50-50 split (I read somewhere that was the goal, but here on this thread I see where Ford may want the steering axle lighter).

I do plan on hitting the scales again for a more complete picture the next time I'm able, but thought I'd throw this out here now to see what y'all had to say. If I'm wasting your time with incomplete data, just say so, I can take it. Either way, thanks.
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Old 11-03-2017, 08:32 AM   #12
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Q. Was the TV and AS loaded for your typical outing, or dry and no gear?
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Old 11-03-2017, 08:33 AM   #13
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Your information is incomplete. In order to determine the effectiveness of a WD set up you need the axle weights of the combination without the WD system in place.

Your current weights indicate the WD hitch should be loaded a bit more and try to get closer to the unloaded weight of the TV front axle.

You will NEVER reach a 50/50 split, an urban myth, as that is a mathematically impossible result. In order to reach such a result the moment arms from the rear axle of the TV to the front axle of the TV would have to be the same as the moment arm from the rear axle of the TV to the center of the trailer axles.
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Old 11-04-2017, 09:14 AM   #14
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Thanks guys. I was loaded for a normal trip, including a half-full water tank. Black and gray tanks were empty.

I know I need to do a more complete re-weigh; was just wondering if I was in the ballpark at this point.

HowieE, I know you’re right about the moment arm. I’ve even resurrected some of my thinking from my college statics classes (many, many moons ago!).

Thanks again for the replies.
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