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  1. #31
    Seasoned Camper Thorvald's Avatar
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    Hmm, that might also explain why the passenger side is getting more hit than the drivers side.

    I’m willing to bet dollars to donuts that with all the appliances (fridges, furnace, pumps, radio, TV, food, plates, dishes AND the storage under the rear bunks is ALL on the passenger side would cause that side to be heavier than the drivers side.

    There is almost no extra weight on the drivers side as the side takes it all up.

    Cheers
    Tim
    2022 Momentum 25G (aka "Baby Mo")
    2020 Ram 3500 Laramie SRW | 6.7 HO Aisin | 6’4” bed | 3.73 gears | air suspension | 3694# Payload
    Blog Post: 1500 Pickup’s and Towing - The REAL numbers with example
    Blog Post: 2016-2018 Imagine 2800BH - 3500 lb Axles Tire Rubbing Issues

  2. #32
    Site Sponsor Cate&Rob's Avatar
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    Tim - Set your trailer parallel to the ground (equalizer centered) and measure the spring arch heights.
    See https://www.mygrandrv.com/fo...ng-Arch-Height for the process.
    This will give you spring compression numbers for each corner that are proportional to load.

    If you want to go one step further, a Sherline scale on a floor jack can be used to lift each wheel position to measure actual weight carried. I did this on a wooden block fitted to the bottom two lug bolts so that I would get weights right at the tire centreline.

    Rob

    Cate & Rob
    2015 Reflection 303RLS

  3. #33
    Site Sponsor theclarks's Avatar
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    Quote Originally Posted by Cate&Rob View Post
    Tim - Set your trailer parallel to the ground (equalizer centered) and measure the spring arch heights.
    See https://www.mygrandrv.com/fo...ng-Arch-Height for the process.
    This will give you spring compression numbers for each corner that are proportional to load.

    If you want to go one step further, a Sherline scale on a floor jack can be used to lift each wheel position to measure actual weight carried. I did this on a wooden block fitted to the bottom two lug bolts so that I would get weights right at the tire centreline.

    Rob

    Rob, can you go into a little more detail on how to get the "each wheel position to measure actual weights", at what point do you stop pumping the jack? My 5K Sherline is to be here Saturday. . . . . .

    Thanks
    Joe & Dee
    Ontario, Ohio
    2018 Chevy 3500HD LTZ Duramax Crew Cab SRW Short Bed Payload 3523#
    2019 Reflection 337RLS bought February 2019 Dry Pin Weight = 2,320#, UVW = 11,100#
    Hitch - PullRite Super Glide 2700 - 16K
    Bed Cover - Roll-N-Lock
    TPMS - Tire Tracker TT-500 (non flow thru)
    Rear Observation Camera - Rear View Safety model RVS-155W-FB (2400-2500MHZ)

    2017 303RLS bought April 2017 / Traded February 2019

    Map represents States visited with our 303RLS /337RLS

  4. #34
    Site Sponsor Cate&Rob's Avatar
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    Quote Originally Posted by theclarks View Post
    Rob, can you go into a little more detail on how to get the "each wheel position to measure actual weights", at what point do you stop pumping the jack? My 5K Sherline is to be here Saturday. . . . . .

    Thanks
    Hi Joe,

    I lift the corner to be tested with my combination bottle jack & axle stand. I measure the distance from the axle to the ground before I start the lift. Then, remove the wheel and lower the bottle jack back to where the axle is slightly below the distance above the ground that it was before you started. Now, using the floor jack, the Sherline scale and the wooden block (note that that is a close grained oak block) lift until the gauge stops increasing, which will be just as the weight comes off the axle stand. The Sherline scale is now holding the same weight that the wheel and tire normally carry. This is best done with the forward weight on the pin, not on the landing gear, using either the truck or a pin tripod. This is because the landing gear is closer to the trailer suspension and will carry more of the trailer weight than the pin would when towing.

    Rob
    Cate & Rob
    2015 Reflection 303RLS

  5. #35
    Site Sponsor theclarks's Avatar
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    Quote Originally Posted by Cate&Rob View Post
    Hi Joe,

    I lift the corner to be tested with my combination bottle jack & axle stand. I measure the distance from the axle to the ground before I start the lift. Then, remove the wheel and lower the bottle jack back to where the axle is slightly below the distance above the ground that it was before you started. Now, using the floor jack, the Sherline scale and the wooden block (note that that is a close grained oak block) lift until the gauge stops increasing, which will be just as the weight comes off the axle stand. The Sherline scale is now holding the same weight that the wheel and tire normally carry. This is best done with the forward weight on the pin, not on the landing gear, using either the truck or a pin tripod. This is because the landing gear is closer to the trailer suspension and will carry more of the trailer weight than the pin would when towing.

    Rob
    Thanks Rob. . . . . . see ya at the Rally. . . . . .
    Joe & Dee
    Ontario, Ohio
    2018 Chevy 3500HD LTZ Duramax Crew Cab SRW Short Bed Payload 3523#
    2019 Reflection 337RLS bought February 2019 Dry Pin Weight = 2,320#, UVW = 11,100#
    Hitch - PullRite Super Glide 2700 - 16K
    Bed Cover - Roll-N-Lock
    TPMS - Tire Tracker TT-500 (non flow thru)
    Rear Observation Camera - Rear View Safety model RVS-155W-FB (2400-2500MHZ)

    2017 303RLS bought April 2017 / Traded February 2019

    Map represents States visited with our 303RLS /337RLS

  6. #36
    Setting Up Camp
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    Quote Originally Posted by Thorvald View Post
    Well you can add me to the Tire Rub issue. I have a the Dexter Axles and the Lippert frame, made in October of 2017. My rubbing is so bad its gone right through the plastic and into the wood subfloor... and I've only been out TWO trips. Not amused.



    Front Passenger Side:



    Front Drivers Side:


    We are out this weekend and I'll do a good check when I have the trailer level to see how much clearance there is etc (sloped driveway so hard to tell).

    I send a contact form in to GD on the Service/Warranty page with the info.


    Cheers
    Tim
    Tim - Have you heard back from Grand Design? If so, what are they recommending?

    Curtis

  7. #37
    Big Traveler
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    Quote Originally Posted by Thorvald View Post
    Hi Dan, I would suspect if anything I am nose low as it is the front axle of the trailer that are showing the rubbing, not the rear axle. Good catch however, I could see on a large road “dip” the hitch rebounding quite low as that is a big trailer.

    I’m considering adding the Airlift 5000 airbags since they now have a kit for Ram 1500’s that does not require cutting off the factory bumpstop and grinding. It’s totally bolt on now.

    I’ll give it a good check today when we hook up and head out, then if I find a difference I’ll adjust the hitch and see if that helps.

    However the spring does look pretty close to flat (very little arch) in the driveway but again, it’s a sloped driveway so can’t be 100% sure until I’m level.

    Certainly not overloaded as we are carrying the same amount of gear that the old Jayco 17z had... but one can’t tell until it gets taken to a CAT scale loaded up.

    More data will be obtained lol!

    Cheers
    Tim
    Tim,

    It is important to have the rig riding level when towing since the front axle will bear the majority of the load when a pot hole or other road hazard is encountered if its riding nose down. However, several of us have had issues with only the heavy right kitchen side where the original clearance is marginal at best. I installed all new OEM springs and lifted the unit by 1.75 inches so I have no clearance issues. But this will not prevent and undersized spring from flattening out, so we will see.
    MidwestCamper

    Jim & Dawn
    Near Milford, Michigan
    2017 Imagine 2600RB
    2015 GMC Sierra 1500 Double Cab 4x4

  8. #38
    Big Traveler
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    Quote Originally Posted by Cate&Rob View Post
    I'm still having a problem with this concept that stronger springs will transmit more load into the frame. I say "still" because I tried to go through this with both LCI and GDRV folks at a couple of different rallies and didn't get very far. I was trying to explain why my Reflection 303RLS which is 800 lbs heavier on the street side needs stronger springs on that side only. I asked if I could meet with their engineers . . . but, nothing came of this. Now, if they are talking about increases in first and second derivative suspension velocity and acceleration, they might have an argument . . . maybe . . . but somehow I doubt that they are that far into this.

    Lets get back to basics. Springs are not very complicated things. There is a simple mathematical equation. F=kx. F is the weight of the trailer. k is the spring constant (or the strength of the spring measured in units like lbs per inch of compression). x is the displacement (or how much the spring is compressed). Let's take the weight of the trailer (F) as a constant for this discussion. The force transmitted into the frame to balance F (to hold up the trailer) is k times x. If k is too small (the spring is too weak) then x will be too big . . . and the tire will travel upward until it hits the body. If we make k bigger (a stronger spring) then displacement x will be less to equal F and the tire will not move up as far and will not hit the body. The force (governed by the weight of the trailer) does not change. It just gets divided differently between spring force (k) and displacement (x).

    Or at least, thats how it worked when I went to school . BTW, stronger springs on the heavy side of my 303 and original springs on the lighter side has worked out very well (for me).

    Rob
    Rob,
    And those springs that many of us are discovering are too light and will suffer from higher velocity and higher kinetic energy. KE=1/2mV^2. As you know, the velocity term is squared so a small increase in velocity will result in much higher energy. The key as you have found is to size the spring accordingly or velocity will increase which can result in higher energy, not into the coach but into the spring which will yield. Cars have different spring rates from front to back so if the loads are different from side to side, the same approach would be needed.
    MidwestCamper

    Jim & Dawn
    Near Milford, Michigan
    2017 Imagine 2600RB
    2015 GMC Sierra 1500 Double Cab 4x4

  9. #39
    Site Sponsor Cate&Rob's Avatar
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    Quote Originally Posted by MidwestCamper View Post
    Rob,
    And those springs that many of us are discovering are too light and will suffer from higher velocity and higher kinetic energy. KE=1/2mV^2. As you know, the velocity term is squared so a small increase in velocity will result in much higher energy. The key as you have found is to size the spring accordingly or velocity will increase which can result in higher energy, not into the coach but into the spring which will yield. Cars have different spring rates from front to back so if the loads are different from side to side, the same approach would be needed.
    Jim (MidwestCamper) - LOL! I knew that if someone was going to bring up the velocity and acceleration of the spring motion, it would be you . I think we need to get the static F=kx understood first .

    In car assembly, (less important for trucks) bumper height is carefully regulated. There are a range of springs for every corner, selected based on vehicle option content to keep the front and rear bumper height within the required range.

    Rob
    Cate & Rob
    2015 Reflection 303RLS

  10. #40
    Site Sponsor jw^2 family's Avatar
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    Our 2018 Imagine 2800BH (and I assume previous model years as well) has axles rated at 3,500-lbs. each and a GVWR of 7,495-lbs. Since our actual UVW came in at a portly 6,564-lbs., by the time we're loaded up and ready to go camping we're running close to the GVWR. When I crawled under our trailer to check torque on the nuts for the u-bolts the other week I noticed that the springs looked pretty flat. We haven't had the tires rubbing yet, but I'll be watching for it.

    I noticed that the Grand Design website lists updated specs. for the 2800BH which include 4,400-lbs. rated axles and a GVWR of 7,995-lbs. It's interesting that while the axles now provide an additional 1,800-lbs. of rated capacity, the trailer's GVWR is only increased by 500-lbs.

    A couple of questions come to mind -
    1) Is this change from 3,500-lbs. to 4,400-lbs. axles due to Grand Design realizing that the springs on the 3,500-lbs. axles just weren't up to the task of carrying a trailer that would commonly be loaded close to the 7,495-lbs. GVWR?
    2) Should those of us with 3,500-lbs. axles be thinking about swapping out for 4,400-lbs. axles, or at least the higher-rated springs, to avoid eventual flat springs and tire-rubbing problems?
    Joe & Joy + children
    2018 Imagine 2800BH
    2022 F250 Crew Cab 4x4 Tremor, 7.3L V8
    Equal-i-zer 1,200/12,000 lb. hitch


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