checking tongue weight with Sherline Scale

[dnhx]

I am planning to check tongue weight on a few trailers at the dealer. If I use a Sherline scale and measure at the tongue jack, about what percentage will it be off from actual tongue weight at the hitch? (I know actual will depend on the trailer design, just looking for ball park.)

thank you

[LarryJM]

Airstreamer67 wrote:
I weigh at the ball coupler too. That way I don't have to use my arithmetical skills, since me and Jethro Clampett never did it too well in skool 😮

To assure the trailer is at the proper attitude, I use a bubble level on the A-frame. I use the same level to make sure the trailer is level when hooked up to the truck, and I center the bubble when measuring with the Sherline. Works good. No figurin' that way.

Same here and my Sherline came with a post that specifically is to use directly under the ball coupler so you are measuring at the correct point. On thing is to get three or four weights moving the Sherline ever so slightly since any slightly off vertical force tends to give some variability in the weights on the Sherline.

Larry

[Airstreamer67]

I weigh at the ball coupler too. That way I don't have to use my arithmetical skills, since me and Jethro Clampett never did it too well in skool 😮

To assure the trailer is at the proper attitude, I use a bubble level on the A-frame. I use the same level to make sure the trailer is level when hooked up to the truck, and I center the bubble when measuring with the Sherline. Works good. No figurin' that way.

[BigToe]

I position the Sherline scale directly underneath the trailer's ball coupler.

In otherwords, the Sherline substitutes for the trailer ball itself.

The trailer ball is where the dead tongue weight is transferred to the towing vehicle (before any weight distribution system is engaged), so it makes the most sense to me to measure at the exact same place.

Measuring directly underneath the ball coupler also provides a more fair comparison from trailer to trailer, regardless of tongue material design or obstructions. No matter how the end of the tongue is shaped, and no matter what kind of hardware appurtenant obstructions exist under the trailer tongue, the ball coupler still has to be able to latch onto a ball with no obstructions.

Why not measure at the ball coupler, and use the tongue jack to raise and lower the ball coupler on and off the Sherline scale in the same manner as raising it off of the ball mount?

The tilt of the trailer effects the measurement of the tongue weight, so having the tongue jack available to adjust the tilt attitude of the trailer to the towing trim is a benefit. I can't imagine anyone trying to place the Sherline scale underneath the foot of the trailer tongue jack... that seems very unsafe.

I would measure the top of ball height on my tow vehicle first, and then recreate that height at home with the Sherline scale. You might be able to find a 6x6 cutoff blocks, or a stack of plastic RV leveler blocks, or a concrete pier block, or a jack stand... an endless number of objects can be placed under the Sherline to ultimately simulate ball mount height.

That ball height will lower once the weight of the trailer is mounted on the ball, but with weight distribution, some of that lowering will be recovered. If the trailer is light enough where no weight distribution is required, then I would consult the tow vehicle manufacturer's specifications for rear spring deflection. For example, the rear springs might deflect 1 inch per 600 lbs of weight added in the first stage, before overloads kick in. Then the second stage might be 1,400 lbs per inch. Whatever they may be, an accounting could be made for this deflection by reducing the height of the Sherline scale by an inch or two accordingly, to best simulate the actual trailer tilt attitude when finally hitched up, which will make for more accurate tongue weight measurements, in my experience.

[Airstreamer67]

mosseater, I do it your way. It takes an inch or less of up/down trailer jack movement to get the weight.

Earlier it was suggested to jump on the tongue to get a good reading. I disagree with this technique. I do, however, raise and lower the trailer onto the scale several times while moving the scale to slightly different positions each time to assure it is evenly balancing the load and thus not in a bind. If the scale is put in a bind by having the load lowered onto it at an angle, it will read lower-than-actual weight values. This can happen because an off-center load will put side-load stress on the scale's hydraulic ram and thus produce erroneous hydraulic pressure to the meter.

[mosseater]

I have several sections of 6x8's that I use as jack pads and such. I just stack them up to the needed height. You only take the weight off with the jack, so if it falls it's not going anywhere. The jack is right there 1/8" off the ground to catch it.

Doesn't matter which way you do it, you still need the trailer chocked good to stablize it. How far is it going to go????? Your way, if it slips off the scale, the tongue jack is the height of the scale off the ground, what, like 6"? My way, the tongue jack is 1/8" off the ground. Which way sounds safer to you?

[2500_Grunt]

If I remember correctly, my scale is only about 10" tall and my a frame is about 25" off the ground. When my trailer is level it has about 18" of wood blocks under the trailer jack. If I lowered it all the way my A frame would still be much higher off the ground than I feel safe with. The scale footprint is just too small and unsecure IMO to have a bunch of 2 by's stacked under it rather than one. I don't want 1500 or more pounds sitting on a scale that has 10" or more of blocks under it. The jack idea is much easier and safer.

[mosseater]

If you have a block of wood to sit the scale on, why can't you use the tongue jack to take it up slightly above level and slide the Sherline under the A-frame just behind the coupler? lower in down on the scale and take the jack just off the ground. I put mine right up in the ball coupler and lower the tongue jack until the scale is taking the weight. At the coupler or right behind, it's only an inch or two, how much difference could there be? Maybe I'm missing something.

[2500_Grunt]

Bring a jack with you and jack it up 8" under the A frame as far up front as you can and put scale under the trailer jack. Make sure wheels are blocked really good. I have one of those Shrline scales and it is pretty accurate.

[TenOC]

dnhx wrote:
I am planning to check tongue weight on a few trailers at the dealer. If I use a Sherline scale and measure at the tongue jack, about what percentage will it be off from actual tongue weight at the hitch? (I know actual will depend on the trailer design, just looking for ball park.)

thank you

I would never make a decision on a trailer based on tongue weight. The weight changes too much based on how you load it -- long trip or short trip. A TT is a long term investment. Buy the floor plan you like, then a truck and hitch (HA or PP) to tow it with extra capacity to spare.

[RCMAN46]

There should be a sticker near the front of the trailer that will give the GVW of the trailer. Take 15% of that number and that is the tongue weight you should be concerned with when looking for a new trailer.

[dnhx]

I want to know what the empty tongue weight is with the options on the trailer. The published tongue weight is without any options, which is kind of a worthless number. I know about what a battery and propane tanks will weigh. Since my TV does not have infinite capability, I would rather know the starting point of a trailer before I buy it.

[handye9]

I'm having trouble understanding why you would want to go to a dealer and measure tongue weights. They will change (75 to 150 lbs) with dealer added options, adding a battery (or two), and filling propane bottles, but, those things normally don't happen until the unit is sold. Thus, a somewhat accurate tongue weight, is already printed on the sticker.

The time to check with a scale would be after loading up for camping.

[Ron_Gratz]

For ball park correction -- multiply tongue jack reading by 0.95.

The actual correction is the ratio of

distance from tongue jack to midpoint between axles

divided by

distance from coupler to midpoint between axles.

On Edit: Had a bit of brain lapse on the first version of this post.
The load measured under the tongue jack will be greater than the load measured under the ball coupler.
Therefore the actual tongue weight will be about 5% less than the load measured under the tongue jack.

Ron

[lbrjet]

I think I remember that info in the owners manual.