I visited the CAT Scale - Opinions welcome

[MISailor]

I visited the CAT scale today to help me decide if I need to use my WD system for my little 19FBPR with my new TV. The manual for the TV says that the WD system is “optional” for trailers under 7000 lbs. I knew I would be well under than limit, but I was a little concerned about tongue weight which is limited to 800 lbs w/o WD according to the truck manual and 600 lbs according to the sticker on the TV hitch.

I took three weights: (1) the truck alone, (2) truck and trailer w/o WD, and (3) truck and trailer with WD. The truck was loaded with me and maybe 50 lbs of stuff in the bed. The TT was only partially loaded with nearly full propane, battery, some gear (chairs, grill, etc.) but no water, food, or clothing. Here are the weights that I found:
1. The truck alone = 5740 lbs (3300 front, 2440 rear)
2. TV & TT w/o WD = 10300 lbs (3060 front, 3260 rear, 3980 TT)
3. TV & TT w/ WD = 10280 lbs (3120 front, 3140 rear, 4020 TT)

If I’m analyzing these data correctly, I have a TT weight of about 4560 lbs and a tongue weight of 580 lbs. We camp light, but I expect that we’ll exceed 600 lbs on the tongue when we’re fully loaded. So that’s enough to convince me to use the WD system.

The TT pulled 240 lbs off the front of the TV, but the WD shifted 60 lbs back so I’m still 180 lbs lighter up front.

Questions:
1. Did I miss anything?
2. Should I try to get a few more lbs shifted back to the front axle?
3. Do I need stronger spring bars (currently using 550 lb bars)?

All opinions appreciated.

[Javi]

You need a couple hundred pounds back on the front axles.. and I'd get me some 750 or 1000 pound bars..

[mhs4771]

X2, you need to get the front end back to where its was. Otherwise you will throw you front alignment off, plus with the front light could be a cause for sway.

[hankpage]

If the rear of your truck empty is 2240 and with the trailer weighs 3260 .... where did you get the figure of 520????? I'm looking at over 1000 lbs. and you're not fully loaded yet. :confused: and how did the whole rig weigh less with WD added?? :confused: :confused:

[MISailor]

If the rear of your truck empty is 2240 and with the trailer weighs 3260 .... where did you get the figure of 520?????

I did have a small math error in my original post (now corrected). It should have been 580 lbs not 520. I subtracted the combined weight on both TV axles with the truck empty (3300 + 2440 = 5740) from the combined weight on both TV axles with the TT attached (3060 + 3260 = 6320). In other words 6320 - 5740 = 580.

[MISailor]

and how did the whole rig weigh less with WD added?? :confused: :confused:

The difference between w/ and w/o the WD is only 20 lbs out of roughly 10,000 lbs. That's only 0.2% which I figured was well within error of a scale designed to weigh loaded semis.

[f6bits]

As a bonus, you can get a WD hitch setup with nice built-in sway control. Yes, your setup is pretty good as it is to prevent sway, but in wind or emergency maneuvers, sway control would be nice.

[jergeod]

I did have a small math error in my original post (now corrected). It should have been 580 lbs not 520. I subtracted the combined weight on both TV axles with the truck empty (3300 + 2440 = 5740) from the combined weight on both TV axles with the TT attached (3060 + 3260 = 6320). In other words 6320 - 5740 = 580.

I have no idea how those figures give you tw. If the truck rear axle weight was 2240 empty and the truck rear weight jumped to 3260 w/trailer that shows you have a tw of 1020 lbs hanging on the rear axle of the truck. You add the wd and now you have 3140 on the rear axle, says you have 900lbs hanging on the rear axle of the truck. The weight has to be on the hitch to add 900 lbs to the rear axle weight. Now if you take the 180 from the front of the truck off the 900 you have a hitch weight of 720.

[MISailor]

The total weight of the unloaded truck is the sum of the weight on the front and rear axles. Likewise, the total weight of the "loaded" truck (i.e. carrying the tongue weight of the TT) is the sum of the weight on both axles when the trailer is attached. The difference between these total weights would be the tongue weight (580 lbs in my case).

Not all of the additional weight on the rear axle is from the trailer. Some has been redistributed from the front axle (note the lower front axle weight with the trailer hitched). This is why the front fender measurement (from the ground) increases when the trailer is hitched. If the load on the front was unchanged, your conclusion that all of the additional weight on the rear would equal the tongue weight would be correct.

To better visualize how weight is transferred from the front to the rear axle with the trailer attached, picture an extreme case where the tongue weight was so heavy that we lift the front wheels of the TV off the ground. In that case 100% of the weight normally on the front axle would be transferred to the rear axle. Does that help?

[TAZ23]

One other thing on the set up. The owners manual for my 2012 (and peviously '06) Silverado states in the towing section that the front end of the vehicle measured at the top of the wheel wells should be returned to the unloaded height after hooking up the WD hitch. My trailer is considerately heavier than yours and after adjusting it according to the owners manual it tows great and it is within vehicle specs. (Weighed on our truck scale at work.) Before doing this the front end was about 1 inch high and there was some noticable sway at times. Also, I would go with the hitch specs over the owners manual for weight purposes.

[B&T]

Question.

In OP,

1. The truck alone = 5740 lbs (3300 front, 2240 rear)

but, 3300+2240=5540

Which is correct?

[MISailor]

Question.

In OP,



but, 3300+2240=5540

Which is correct?

I was having serious typing issues last night :banghead:. The correct total for the TV alone is 5740 (3300 + 2440).

[MISailor]

Thanks to all who have replied to this thread. I appreciate the input, especially the challenges to my calculations. I believe that this is an important topic directly impacting our safety and that far too few take it seriously and then wonder why their trailer gets “squirrelly”. I’m somewhat ashamed to admit that I pulled this same TT half a dozen times with an Astro.

One of the reasons that I visited the scales in the first place is that I experienced only about a ¼” lift in the front end of the new TT when I hooked up, and I was unable to change that number much with the WD system. My take away from all of this is that my TT is reasonably balanced, but I need stronger bars to balance the TV correctly. The bad news is that my WD is so old; I won’t be able to just get stronger bars because the hitch head has been redesigned. So while I’m spending more $ than I planned, I’ll probably upgrade to a dual cam system and remove my friction sway controller.

[Ken / Claudia]

Information about DOT scales, I was trained to use them and did for about 15 years, I would open them to have a place to finnish writeing custody reports etc. and wt. afew trucks. In Oregon(it maybe different else where), The wt. reading is allowed to be off as much as 200lbs, this is due for the large wt. they are made for and per court room they are set up so that Max. error could be as high as 200 lbs light or heavy. So when we wt. smaller loads in the 3000 lbs for example you can still be off 200 lbs. Just keep that in mind when useing the scales. I have not had training or worked in the scale houses since 2002, I do not think anything has changed here since then.

[MISailor]

The wt. reading is allowed to be off as much as 200lbs.......

I suspected as much given my experience calibrating scales in the pharmaceutical industry. My work was on a smaller "scale" so to speak, but the principle remains the same. That's why I was actually very pleased/surprised to see that my CGVW only differed by 20 lb (about 0.2%) on two separate weighs.

[labs4life]

Correct sir. Lumber yards around N GA with scales say they are calibrated +- 200 lbs.