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MHay's avatar
MHay
Explorer
Aug 25, 2020

Help Deciphering CAT Scale Weights

Hi all,

New to the forum, and to RVing. I want to make sure my WDH is adjusted properly. I took my rig and travel trailer (TT) to the scales this past weekend and did three passes: first was hooked with WDH bars in place, second with WDH bars released, and third was rig and trailer separated. The weights are below. What I'm trying to determine is whether or not I can get more weight off the rear axle and distributed to the front and TT axles. Weights displayed are in pounds.

1st Pass (Connected with WDH bars):
Steer Axle: 3,020
Drive Axle: 4,560
Trailer Axle: 6,560

2nd Pass (Connected without WDH bars):
Steer Axle: 2,740
Drive Axle: 4,960
Trailer Axle: 6,460

3rd Pass (Disconnected trailer from rig):
Steer Axle: 3,200
Drive Axle: 3,560
Trailer Axle: 7,400

From these measurements, I calculate the tongue weight to be 940 pounds (7,700-6,760). Comparing pass 1 with pass 2, using the current setup the WDH bars seem to add 280 pounds to the steer axle, take 400 pounds off the drive axle, and add 100 pounds to the trailer axle. Should I be aiming for more weight on the steer axle (it's 180 pounds lighter than normal drive weight), and less off the drive axle (1,000 pounds more than the normal driving weight). And with only 100 pounds being transferred to the trailer axle, it seems like there's more that could be moved there.
  • Good, you're on your trip and not pining over this. Still didn't answer the question of how it "looks" and how it "pulls".
    Too much of the time, folks get wound up in splitting hairs on the numbers and, well, honestly that seems to only be a "thing" in the RV world.
    If it was that critical, the other millions of light duty trucks pulling...whatever...around daily would need greater scrutiny.
  • Tilting the WD Hitch head only moves the bar farther away from the tongue mounted brackets...but...the bar spring rating does NOT change. Just bending it more and at some point, the bar may deform enough to never again have the same rating...less spring bar rating

    Why asked what the bars are rated for. If you bars has enough spring rating, then tilting the head will be fine

    Your WD Hitch uses the friction between the bar bottom side against the bracket and the wearing of the paint part of how it works

    It will make metal on metal noise and too often read here that someone advises to grease/oil that union

    Since friction is the main anti-sway component (not as much friction as a friction bar would provide) and adding lubrication an oxymoron...though many do so. I don’t recommend it...even knowing that several OEMs instruct to do so if the noise annoying

    Your amount of ‘over’ weight on the rear axle isn’t going to have the rear axle fail instantly...just wear a bit more than if below the rating....butt....that will not have any head room for that occasional added weight

    Edit...just remembered that some say the newer versions of this type of WD Hitch now has friction material on the bracket that the bar rides on. Now that is the same as traditional friction bars and should remove the metal on metal noise, but think it will still have some noise (haven’t seen one yet)

    Maybe your OEM has an upgrade kit to add a friction pad on each side
  • MHay wrote:
    Snip...
    I'm using a Curt TruTrack hitch rated at 15,000 GTW and 1,500 TW. Currently I have the brackets on the trailer as high as they'll go. I have not tried tilting the hitch head yet, which I believe would apply more tension. As it is now, the trunion bars seem to be exerting lots of force on the angle brackets, to the point where they are wearing through the black paint on the front of the brackets and starting to mar them. Should I try tilting the hitch head back in an attempt to get more weight off the rear axle, or does it seem like I'm fairly maxed out already? Here's a link to the instructions: Curt TruTrack Hitch.

    We're headed on a trip tomorrow, so I'll try to get a picture of the current setup once I'm hooked up.

    You mention that the paint is wearing on the front of the L shaped angle brackets. You also state that the brackets are as high as they can be on the frame. That tells me that you should lower your brackets on the frame and then also tilt your hitch head rearwards. The spring bars should rest evenly on those brackets - not contact them just on the front edge or rear edge like they are doing now.

    I would aim for getting the brackets at the right level so the bars rest evenly across the surface. Than I would tilt the hitch head rearward until I got the weight transfer that I wanted.

    This all assumes that you trailers A frame can take the stress of the additional pressure the WD bars will put on it via the brackets. You have very strong, square, non tapered WD bars that are not too flexible. It is not unheard of for A frames to bend or break from excess WD pressure, especially when going through a dip like you would find at a gas station or other driveway or even some RR crossings. If your frame is a 6 inch frame or larger it should be ok.
    Barney
  • BarneyS wrote:


    I would aim for getting the brackets at the right level so the bars rest evenly across the surface. Than I would tilt the hitch head rearward until I got the weight transfer that I wanted.

    This all assumes that you trailers A frame can take the stress of the additional pressure the WD bars will put on it via the brackets. You have very strong, square, non tapered WD bars that are not too flexible. It is not unheard of for A frames to bend or break from excess WD pressure, especially when going through a dip like you would find at a gas station or other driveway or even some RR crossings. If your frame is a 6 inch frame or larger it should be ok.
    Barney


    I finally took the time to make some adjustments. I added the larger spacer to tilt the head back some more. I also dropped the frame brackets by one notch to relieve some tension and to level out the bars. I tried it out at that setting and it “felt” like there was too much tension. I could see the bars bending when tensioned and there was lots of additional popping noises when driving. I then lowered the brackets one more notch and that seemed to be a good balance.

    I stopped at the scales yesterday on our way home from a trip and the numbers confirm that the weight has been spread to the TV front axle and TT axles. Note: trailer weight has increased by 420 pounds due to water and other cargo. Despite the extra weight the adjustments have still taken more weight off the rear axle and moved it to the front axle.

    TV Front Axle: 3,120 (was 3,020)
    TV Rear Axle: 4,480 (was 4,560)
    TT Axles: 6,960 (was 6,560)
    New Gross Weight: 14,560 (was 14,140)

    I’m still 100 pounds above the rear GAWR for my truck, so I’m considering adding the last washer to tilt the head back to its max, leaving the frame brackets where they are, to see if I can squeeze anything else out of it.

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