Is there a way to distribute weight with a 5th wheel?

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bigtexan99

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I weighed my truck with no trailer and the weights are

front axle - 4160
rear  axle - 2780

with the 5th wheel, the weights are

front axle - 3800
rear axle - 5740

Is there a way to distribute some of the weight back to the front axle?  What is the best way?

Thanks!
 

Bob Buchanan

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bigtexan99 said:
Is there a way to distribute some of the weight back to the front axle?  What is the best way?

It would seem to me that moving carrying load weight from forward of the 5th wheel axles to aft of the axles would lessen the hitch load and increase the load on the front truck axle. But then I'm not a trailer guy anymore . . .  :)

OTOH, why would you want to do that? Isn't the concept of a 5th Wheel to place the load over the rear axles on the truck. When a truck is not carrying a load of any kind, would imagine the rear weighs less, but thta where the strengh is to handle the most load.
 

Lou Schneider

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If you're removing weight from the truck's front axle when you hitch the trailer it means the 5th wheel platform is located behind the truck's rear axle.  Moving the hitch to directly over the axle or 6" ahead of it will prevent the trailer from removing weight from the truck's front axle.  If you have a shortbed truck this may raise clearance issues between the truck cab and the front of the trailer during turns, which can be solved with a slidier hitch (forward for normal towing, back when you need clearance during a turn).
 

Gary RV_Wizard

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It would be a very odd installation if the hitch were actually behind the rear axle center point, though I suppose anything is possible! I suspect his fifth wheel is right over the axle rather than behind it - it could still lift the front slightly as the rear end settles under that heavy pin weight.  When the rear end settles several inches, the angle changes  from the typical nose-down aspect of a diesel pick up to a level or tail down aspect, which has the effect of slightly shifting weight off the front axle.  There's only 360# difference on the front end.

I wonder if shifting some weight in the fiver towards the rear would help. That should reduce the pin weight a bit and let the rear truck axle come up somewhat, which has the effect of transferring weight forward. Don't have any idea how much the pin weight would have to come down to make much difference.

Almost 3000 lbs increase on the rear axle is a lot - is this truck rated for that much?
 

bigtexan99

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The hitch is mounted directly over the rear axle and the truck is a shortbed.  I suspect that the weight of the kingpin is 'cantilerving' the truck somewhat so that some of the weight is taken off the front.

The current payload is just over what I would like it to be, so thats why I'm asking if there is a way to re-distribute.

My plan is to move some personal items (about 100 pounds) from the very front of the 5th wheel to the 5th's center axles.  Also, my freshwater holding tank is at the very back of the 5th wheel, and it was almost empty at weigh time.  I suspect filling it with 40 gallons (320 pounds) should help, by 'cantilerving' the 5th wheel, just as the kingpin is doing to the truck.

Your thoughts and ideas are appreciated.

One more question, would putting an airbag or heavy duty shocks to stiffen up the rear of the F250 have the effect of 'un-cantilerving' the truck and shifting some of the weight back to the front of the truck?
 

BruceinFL

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Sounds to me like you may have too much trailer for an F250. Assuming a pin weight that is 20% of the trailer weight, that makes your trailer around 15000 lbs. Sounds like you may be exceeding the Gross Combined Weight Rating (GCWR) of your truck. Also check your truck's rear axle weight rating, which you may also be exceeding in addition to putting extra stress on your tires.

That being said, I see an awfull lot of big rigs being pulled by F250s. And there are people who have added springs, etc. I faced the same situation and traded my F250 for an F350 and have never looked back.

 

Gary RV_Wizard

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Putting some water in the tank and moving some gear to the stern should help a noticeable amount.  Please let us know the results.

However, the added water weight will add to what I feel sure is an over-GCWR problem.
 

Carl L

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RV Roamer said:
Putting some water in the tank and moving some gear to the stern should help a noticeable amount.  Please let us know the results.

However, the added water weight will add to what I feel sure is an over-GCWR problem.

You may have a point there.  Those axle weighing could indicate a trailer weight from 13,000 to 17,000 lbs.  Maybe we should get info on the truck specs and the trailer GVWR or actual weight.
 

bigtexan99

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I won't be testing the water in the rear of the trailer theory until next week when I move the 5th wheel again.  I will let you know the results.

The current weights I have for the trailer are

Truck - full fuel and passengers
faxle - 4160
raxle -  2780
total - 6940

Truck - full fuel and passengers plus 5th wheel hitch and extraneous items in the bed of the pickup.
faxle - 3800
raxle - 5740
total -  9540

Trailer
kingpin - 2600 lbs
rear tandem axles  - 9980
entire truck and trailer - 19360
entire trailer - 12420

The GVWR of the 5th wheel sticker is 11,500

So it seems to me that I need to shift some of the weight off the kingpin, back to the trailer axles where I have some extra capacity.  I'm assuming that the rear axles of the trailer can handle up to 11,500 and the kingpin load is seperate.  I hope I'm not wrong on that.  Otherwise my trailer is over it's GVWR without any personal items in there.

 

Lowell

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Are you sure these scale weight are correct?  It doesn't seem possible to get and additional 2600 lbs in the truck from just the 5th wheel and some misc. items.
 

Gary RV_Wizard

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I'm assuming that the rear axles of the trailer can handle up to 11,500 and the kingpin load is seperate.  I hope I'm not wrong on that.  Otherwise my trailer is over it's GVWR without any personal items in there.

Wrong. The GVWR is the the max total trailer weight. Your trailer's DOT sticker should show the GAWR for each axle, as well as the GVWR. I wouldn't be surprised if the total max load for the two axles is around 9000 lb, since it is a distressingly common practice for manufacturers to size the axles for the GVWR minus the kingpin weight.

And unless you have a late model F350 or 3500 diesel truck, you are probably over the truck GCWR as well. What year, make, model and configuration (cab style, axle, engine, 2WD/4wd) is it?
 

Lowell

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bigtexan99 said:
Truck - full fuel and passengers
faxle - 4160
raxle -  2780
total - 6940

Truck - full fuel and passengers plus 5th wheel hitch and extraneous items in the bed of the pickup.
faxle - 3800
raxle - 5740
total -  9540

Ok, I misread the second part as including the 5th wheel hitch but not the trailer as it wasn't mentioned as being hooked up.  I thought that seemed like a lot of weight for just the installing a 5th wheel hitch.
 

Gary RV_Wizard

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According to the 2002 Ford Towing Guide (latest I can find on the Ford site), the 2002 F250 Supercab has a 20,000 lb GCWR. I had a 99 like yours and my somewhat shaky memory says the GCWR on that was 19,000 rather than 20k. So you are either close to or slightly over GCWR.

Max trailer for the 2002 is shown as 13,400 lbs. Again, I think the 99 was rated a bit less.

The biggest issue will be the truck's rear axle GAWR - I'm pretty sure you have reached or exceeded it with that much pin weight. It should be shown on a sticker somewhere on the truck - either on the door post or in the glove box, would be my guess..

I doubt if you will have a performance problem - the 99 was a strong running truck. Whether it is stressing other chassis components too much is another issue. I know I would want an exhaust brake with that much weight behind me.
 

bigtexan99

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Thanks for all your input.  My search turned up the following numbers for my 99.

20,000 GCWR
13,800 5th wheel towing.

So I figured I was just under the limits, the only unforseen issue I have is the higher than expected pin weight, which would be resolved if I can shift the weight back to the front axle or back to the trailer axles.

I will work on getting that down by doing some weight shifting and/or purging of content from the trailer.

 

Carl L

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Yeah it would seem that even a 99 should be able to haul that fiver.  Filling the fresh water tank will help as will moving the forward stored gear back.  The whole problem is one of weights about the center of rotation of the trailer which is somewhere in the middle of all the axles -- the moment arm.  The weight bearing on the pin is the some of all the of the moment arms of the items of the payload.    300 lbs 10 feet behind the center of rotation will balance 150 lbs 20 feet ahead of it and reduce the weight effect of the load on a the hitch pin to zero.
 

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