Forum Discussion

SDcampowneroper's avatar
Jan 02, 2015

weight capacity. Add an axle?

A guest arrived this past summer with a Holiday Rambler 5er carrying a Harley on a Hydrolift. He had 3 axles. HR never made a triple in a non toy hauler that I know of, so I asked about it. He added the third axle for the weight capacity. very professional job of it too, I add, as an old steel worker myself.
I raise this subject because there are many of us( me included) who would like to take along toys but see some state restrictions of a second trailer or even frame extensions like Idaho Totes being scrutinized by LEOs as double tows.
To you many toy hauler advocates this is an issue for us many who choose our unit for living space, with the toy capacity secondary.
To the handy this is an inexpensive addition to increase capacity. whether you want to carry a M/C, or just a genny and the kids bikes.
After my recent failure of MorRyde equalizers that demonstrated inadequate capacity (see previous posts) even though we are within weight limits. I have been thinking hard on adding an axle as the cure for that as well as capability to add a rack/ lift to bring toys.
My idea is to add a 5200# axle with trailing arms, air bag lift wheel skirts from a TT ro match, well behind the primary 7000# tandems. It would look no different than youv'e seen on many a dump or cement truck with a tag. An easy job in my shop.
That way, we can adjust carrying capacity to the load.

20 Replies

  • I have been thinking hard on adding an axle as the cure for that as well as capability to add a rack/ lift to bring toys.
    My idea is to add a 5200# axle with trailing arms, air bag lift wheel skirts from a TT ro match, well behind the primary 7000# tandems. It would look no different than youv'e seen on many a dump or cement truck with a tag. An easy job in my shop.
    That way, we can adjust carrying capacity to the load.

    I don't think a 5.2k axle/wheels/tires could take the abuse.

    Well behind the two 7k axles ? Several inches or several feet ? You would sure have to do some serious engineering and use heavy materials in the fabrication.

    Sounds like your sitting up a drag axle. Truck/trailer drag axles I've seen are usually of the size of the primary axles as they will have tremendous side loads applied while they side scrub wide around a corner.
    The two 7k tandams will carry the load while the drag axle slides a big radius behind them as the trailer goes around a corner.

    Interesting concept. If you decide to go with the drag axle I would use a tire and wheel with the heaviest capacity possible such as a Load G tire and wheel..

    I'm surprised the RV industry hasn't gone with a spread axle on the heavier units.
    I know the GN trailer (equipment and flatdeck) industry has started using spread axles on units with tandem 7k-10k axles. Drivers with 3500/4500/5500 size trucks report a much better truck ride/better straight line tracking in strong side winds/less load on the trucks drive axles and less worry about load placement on the trailer.
  • The strength of the frame would concern much more than having the number of axles to carry the weight.
  • x2 I would worry about needing & how much to beef up the frame as they are minimal now......... We did the TH thing the garage is a great extra bedroom or living room no loss of living space.
  • We Cant Wait wrote:
    Sure you can add axles to handle the extra weight you want to haul, BUT WILL THE FRAME HANDLE IT????
    This is a very valid concern.
    I had my frame increased from 1/8" to 1/4" sidewalls on the rectangular tubes when I ordered it and the Mobile Suites has a 15" stacked frame to start with. This is more than most companies install.
    Excel has a 10" frame and offered an option to install the Hydralift motorcycle carrier on their shorter models. I believe it was 32' or less but they have stopped offering it as an option after they had problems when they installed one on a 36 or 38' model and had the frame twist or bend causing slide out problems.
  • Sure you can add axles to handle the extra weight you want to haul, BUT WILL THE FRAME HANDLE IT????
  • Ivylog's avatar
    Ivylog
    Explorer III
    I saw something similar this summer in a CG in Canada. It caught my eye because the tires on the third axle were smaller than the rest so no need for fender cutouts. He had added a 6' storage box to the back which was not noticeable as it was painted the same as the rest of the trailer.
    It was unoccupied while we were there so all I can tell you is it was a torque flex axle with 14" tires.
  • Our current fiver is a Mobile Suites 38TKSB3 which is perfect for us as full timers looking for a very liveable RV. I had the Hyrdralift installed to carry my 700 lb. motorcycle. I wanted DRV to add the third axle during manufacture but they wouldn't because of the Lippert warranty. I had a third axle added by my local mechanic and it has turned out well. I now have three 8,000 lb. Mor/ryde Independent suspension axles and only a 10 foot overhang from the rear axle to the rear of the trailer.
  • Well in your friend's case, the extra weight was all behind the rear most axle, and the added "Lift" of say 4,000 pounds up would only compensate for the 1,200 pounds lift and Harley weight going down, and some 6-8 feet behind the rearmost factory axle.

    Say your wheelbase is 180" (15 feet is a easy measurement) and your next axle center is an additional 48" behind the factory rear axle.

    If you transfer 2,000 pounds off the rear of the trailer (either remove a LOT of factory installed equipment like the stove and refrigerator) or install the additional axle and move the weight onto it. Then this will move your weight center of gravity forward, and put more weight on the hitch.

    If you also need to remove hitch weight, then the additional axle would need to be in front of the factory axles, and then it will transfer a lot of weight off the hitch and move the center of gravity rearward a LOT. So if you place 2,000 pounds on the center mounted axle, it might take 500 pounds off the pin, and place some extra weight on the rearmost axle.

    Fred.