Back from the scales

[GMT830]

Went to the scales at the transfer station today. Pretty surprising numbers. I went with just Lena, me, full tank of gas first trip.

Front axle 3200
Rear axle 3000
Total of 6200

Lena's a big girl, little heavier than I expected truthfully. With a 7200 GVWR doesn't leave much payload.

Went back with the TT attached. When I pulled in there wasn't anyone in line. As soon as the front tires hit the scale there were four trucks behind me so I didn't have time to unhitch, disconnect the bars, anything. I could have gone back around but the weather was lousy and I just wanted to get some rough numbers.

Front axle 3000
Total of 7200
so the rear was at 4200

Pulled the trailer on and GCW is 12600. The trailer is 6400, that number I'm sure of. Also little heavier than expected. When we were registering it the book showed a weight of about 5200. I would expect that's a base weight without the roof AC, propane bottles, battery, spare tires, etc. And I know I have at least 200# of water on board.

My real question is the tongue weight. Lena went up by 1000#. Is that my true tongue weight? Or are the spring bars moving some tongue weight back to the rear trailer axle meaning it's actually higher? It's leaf suspension with an equalizer between axles. I might try the bathroom scales and lever trick this weekend to get a dead weight figure.

The camper has a front kitchen which we really like, but I knew TW would climb quickly. I tried to tell the DW, but you know how that goes.... Definitely need to move some stuff to the back. Twin 30# propane bottles are right on the nose. For reference, one is empty, the other only a third full or so. I might switch to two 20# tanks and move the tray back as far as possible. For the battery I have a couple options. First is to put an Optima in the bedroom closet. Behind the rear axle and right over the distribution box. Or much cheaper use a Lawn and Garden battery on the tongue. We don't intend to do any dry camping.

[DiskDoctr]

Sounds like you aren't distributing enough tongue weight with your hitch.

Did you adjust your hitch using a tape measure?

Here is a link to one of the best writeups I found on adjusting a WDH. Not sure where I got it, so I uploaded it to this link for your convenience.

http://www.diskdoctor.us/camper/uploaded/How%20to%20Adjust%20the%20Weight%20Distributing%20Hitch.pdf

My apologies to "Bill Jeffery" the author for not linking the original 😉

[GMT830]

Francesca Knowles wrote:

GMT830 wrote:
Lena's dimensions.....

FGAWR = 3,555#
RGAWR = 4,000#
GVWR = 7,200#

We need to move some weight off the tongue of the trailer, plain and simple. I'm considering moving the propane bottles to the rear bumper of the trailer.

Dunno if/where it's in DOT regs, but rear bumper mounting of propane bottles is against the code standards established by the NFPA.

Here quoting from this link:

NFPA wrote:
5.2.3.4 Containers shall not be mounted on the exterior of the rear wall or the rear bumper of the
vehicle

Interesting reading, for a while anyway. I think I could comply with the law by extending the trailer frame enough to mount the tanks, then re-attaching the bumper.

I'm nearly certain I have seen Truck Campers with a propane tank sitting on a fold down shelf on the rear of the camper. And it was factory.

[Francesca_Knowl]

GMT830 wrote:
Lena's dimensions.....

FGAWR = 3,555#
RGAWR = 4,000#
GVWR = 7,200#

We need to move some weight off the tongue of the trailer, plain and simple. I'm considering moving the propane bottles to the rear bumper of the trailer.

Dunno if/where it's in DOT regs, but rear bumper mounting of propane bottles is against the code standards established by the NFPA.

Here quoting from this link:

NFPA wrote:
5.2.3.4 Containers shall not be mounted on the exterior of the rear wall or the rear bumper of the
vehicle

[GMT830]

Lena's dimensions.....

FGAWR = 3,555#
RGAWR = 4,000#
GVWR = 7,200#

We need to move some weight off the tongue of the trailer, plain and simple. I'm considering moving the propane bottles to the rear bumper of the trailer.

[brulaz]

GMT830 wrote:
Thanks for the info guys. Ron, curious how you arrived at the TW. And getting 200# back on the steer would be perfect, put it back at the original point. The airbags in the rear coils allow me to maintain desired ride height.

Thinking about this I realize I can remove about 50 lbs from the tongue by draining the HW heater, it's right at the front of the camper. I haven't looked yet but I presume I can install some sort of quick drain?

I'm switching hitches on Monday after the rain ends. Going from a cast shank and round bars to a steel shank with Trunnions. And Dual Cams. I modified the shank to move the ball forward about three inches. I'll put up pics of the before and after setup.

Tightening your WDH up will certainly get some lbs off the truck. If Ron's assumptions are correct, about 80#. Not a lot, but perhaps more importantly it will take maybe 280# lbs off the rear axle. You didn't mention your truck's rear GAWR, but this may be more out-of-spec than your GVWR when loaded?

Also if you start draining your hot water tank, and if you're like me, you'll need a spare heating element for when you turn it on w/o water. :B

[Ron_Gratz]

GMT830 wrote:
---Ron, curious how you arrived at the TW.---

The net load removed from the front axle is a function of three TV/TT dimensions and two unknowns: 1) the tongue weight, and 2) the load transferred to the TT axles by the WDH.

The net load added to the rear axle is a different function of the same TV/TT dimensions and the two unknowns.

This means we have two simultaneous equations from which the two unknowns can be calculated when we know/assume three TV/TT dimensions and the net load changes for the front and rear axles.

The solution for tongue weight is as follows --

Let: a = TV wheelbase, b = TV ball overhang, c = distance from ball to midpoint between TT axes.

Let: C5 = (b+c)/a, C6 = (a+b+c)/a, C7 = b/a, C8 = net load added to TV's rear axle, and C9 = net load removed from front axle.

I then assumed: a = 130", b = 65", and c = 255".

The measured values for C8 and C9 were 1200# and 200# respectively.

The equation for tongue weight is --

TW = (C8*C5 - C9*C6)/((1+C7)*C5 - C6*C7).

For the assumed and measured values,

TW = (1200*2.46 - 200*3.46)/(1.5*2.46 - 3.46*0.5) = 2260/1.96 = 1153# rounded to 1150#.

The load transferred to the TT axles then is equal to the tongue weight minus the load carried by the TV or,

load transferred to TT = 1150# - 1000# = 150#.

Ron

[Ron_Gratz]

ChooChooMan74 wrote:
Travel trailers need 3 passes. Truck alone, truck and trailer with WDH on, and truck and trailer with WDH off (but sitting in the bed of the truck).

Reason you need 3 is because with the WDH engaged, you can see what your true tongue weight is, and can't determine how much is transferred off the rear axles and to the front and trailer axles.

If you don't have weights for "truck and trailer with WDH off", you can get a reliable estimate of TW by applying some physics and algebra to the results of the other two passes.

Even if you do have the loads from "truck and trailer with WDH off", you don't necessarily get an accurate measure of tongue weight.
If the hitch is depressed too much by the TW, the TT is in a "nose down" attitude and that can give an indicated TW which is different from the actual TW.

Ron

[GMT830]

Thanks for the info guys. Ron, curious how you arrived at the TW. And getting 200# back on the steer would be perfect, put it back at the original point. The airbags in the rear coils allow me to maintain desired ride height.

Thinking about this I realize I can remove about 50 lbs from the tongue by draining the HW heater, it's right at the front of the camper. I haven't looked yet but I presume I can install some sort of quick drain?

I'm switching hitches on Monday after the rain ends. Going from a cast shank and round bars to a steel shank with Trunnions. And Dual Cams. I modified the shank to move the ball forward about three inches. I'll put up pics of the before and after setup.

[Francesca_Knowl]

GMT830 wrote:
For the battery I have a couple options. First is to put an Optima in the bedroom closet. Behind the rear axle and right over the distribution box. Or much cheaper use a Lawn and Garden battery on the tongue. We don't intend to do any dry camping.

If you're considering an Optima battery because you think it's safer inside, please think again. I'm following a thread at another site where some folks were run out of their trailer by a couple of Optimas melting down. They were inside, and not in a vented-to-the-outside battery box. It's a long thread, but even an Optima high muckie-muck weighs in and he says that they'd never recommend that any battery including their own be placed in an unvented-to-the-outside living area.
Link to thread.


If you must put the battery inside due to weight considerations, just keep your regular battery and spend what you save on a vented battery box like this one to contain it.

[ChooChooMan74]

Travel trailers need 3 passes. Truck alone, truck and trailer with WDH on, and truck and trailer with WDH off (but sitting in the bed of the truck).

Reason you need 3 is because with the WDH engaged, you can see what your true tongue weight is, and can't determine how much is transferred off the rear axles and to the front and trailer axles.

[Ron_Gratz]

Your scales numbers indicate
the tongue weight is about 1150#
with approximately 150# transferred to the TT's axles by the WDH.

If you can transfer an additional load of 80# to the TT's axles,
you will transfer approximately 200# more to the steer axle
and will remove approximately 280# more from the drive axle.

Ron