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What ball mount is everyone using for the Bosal tow hitch?

Discussion in 'Model X' started by 7racer, Jun 4, 2016.

  1. 7racer

    7racer Member

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    I was curious for the people already towing with the tow package.

    From this thread we know that the X uses the "Bosal" European tow hitch system
    Tow Package vs. Accessory Hitch

    I purchased a Reese ball mount which has the right rise for my trailer.
    http://www.amazon.com/Reese-Towpower-21330-Class-Forged/dp/B000KKJRS6?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_search_detailpage

    but when I try to put the ball mount into the receiver, the end part (past the lock hole) is so long that it bottoms out on the Bosal hitch receiver (since it's a right angle) preventing the holes from lining up.

    I tried to see if I could find what the europeans do and did a google search but surprisingly have been coming up empty.

    Any suggestions?!?!
     
  2. ccutrer

    ccutrer Member

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    I was planning on getting https://www.amazon.com/dp/B000CQUOPS/ref=cm_sw_r_cp_api_dJ0uxbH402477 since I already have the interlock ball. Now you've got me worried that it won't fit.
     
  3. Gwgan

    Gwgan Almost a wagon

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    Short stem with a 2" rise plus ball height to fit trailer. I can reverse the tongue and use this
     

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  4. Phil Seastrand

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    You need to measure the length from the back of the receiver to the holes and make sure that it fits. In my case the problem was the tongue to hole distance was 1/16" too short and I had to grind it enough to fit.

    My biggest complaint is that the chain rings are too far back and I'm going to have to buy extensions.
     
  5. 7racer

    7racer Member

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    ok I got it worked out. Ended up running to Lowe's with the receiver in hand trying them to see if they fit.
    I found the Reese 70628 to fit. It has the right rise for my trailer so worked great.

    You can see the first picture with the model number. Second picture with my hitch that I ordered off of Amazon (another Reese) and this one.

    Finally, getting it to tow!

    **one issue I have. When I test installed the hitch, it wouldn't release unless I lightly banged on it with a rubber mallet. The locking ball would seem to get stuck. I thought I was fine but when I tried to release it, no go. It's stuck. I'll try again tomorrow but made an appointment at the SC to see if they can fix it.
     

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    • Informative x 1
  6. CmdrThor

    CmdrThor Member

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    Are you concerned that the manual specifies a maximum 3/4" rise and to not use any type of drop ball mount?

    Screen Shot 2016-06-29 at 10.49.26 PM.png
     
  7. ccutrer

    ccutrer Member

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    I don't know how you could use any sort of drop - it sits so low already I'm afraid the hitch receiver itself will scrape. As for rise - I know about the limitation in the manual, and I'm debating if I follow that or if my trailer should sit level like you're supposed to. Currently leaning towards the latter (I'm guessing a 3" rise). Just doesn't make sense to me how they could prescribe that when the entire design of the trailer is outside their control. So long as you don't exceed the specified tongue weight, and your ball mount is rated for the tongue and pulling weights at that rise, seems fine to me. Of course I won't be anywhere near the tongue or pulling limits, so I'm not overly concerned in general.
     
  8. Gwgan

    Gwgan Almost a wagon

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    I agree with ccutrer, the rise was chosen to suit the trailer.
     
  9. CmdrThor

    CmdrThor Member

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    I'm inclined to agree with the two of you as well. That was the first time I read that section of the manual and it was quite surprising after I installed the hitch to measure. It's quite low to the ground.

    I don't own a trailer but I am renting a camper trailer for a trip. They say it's 21 inches from the top of the coupler to the ground. I can subtract the ball height out of that, but it's still a pretty significant rise compared to what is specified in the manual.
     
  10. ccutrer

    ccutrer Member

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  11. Hengist

    Hengist Member

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    The higher the rise, the more the force vector loads vertically rather than forwards. That increases the unloading of the front of the car, making steering less effective, especially when you brake. A load leveling hitch torques the hitch to even up the front to back load ratio. But Tesla does not say much about that.
     
  12. ccutrer

    ccutrer Member

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    Right. What I'm saying is that I could have a no rise ball mount, which causes the trailer -- due to its own design -- to tilt forward and put more downforce on the hitch than if I were to use a rise on the ball mount and have the trailer sit level, equally distributing the vertical force between the trailer tongue and the trailer's axle(s). Of course, the mistake you see more often is a large 4WD SUV or truck with no drop, towing a trailer angling down towards the back putting all of the vertical force on the trailer axle, and none on the tongue.

    As for weight distributing hitch - my inference from no mention of them by Tesla is that either they have not tested/rated for them, or they already know that the more unusual forces put on the vehicle by a weight distributing hitch is somehow not compatible with the chassis or hitch mounting system on the X.
     
  13. Hengist

    Hengist Member

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    I see. The trailer CG is slightly forward of its front axle. The force down on the ball mount is the trailer weight times distance of CG from axle divided by distance of front axle to ball mount. Angle of hitch does not change that. Or do I have the physics wrong?
     
  14. ccutrer

    ccutrer Member

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    Oh man, now you have me going back to high school physics. And all I'm remembering is how to find the amount of force perpendicular to a ramp in order to calculate the total force in the direction of the ramp (i.e. gravity pushes directly down. you split that into a force perpendicular to the ramp, multiple by mu-static and/or mu-kinetic depending on what question you're answering, and subtract the friction force from the remaining portion of the gravity force pointing down the ramp). A picture Static Friction along Ramps - For Dummies (though that is going up the ramp, not down).

    Thinking more, I think your basic calculations are correct, but you're assuming perfectly horizontal distances for how much gravity plays where. When you angle the trailer down towards the vehicle, you create a triangle between the vehicle, the CG, and the actual horizontal distance that splits the CG between the vehicle and the axle. The horizontal distance will get shorter the more extreme the angle, moving the horizontal component of the CG closer to the vehicle, and thus resulting in more tongue weight. A crappy picture, with made up numbers: Dropbox - Screen Shot 2016-07-07 at 10.35.00 AM.png When the trailer is angled, the weight is still 5' back on the trailer, but horizontally it's now at say 4' from the vehicle, so the vehicle is carrying more of the load.
     
  15. Hengist

    Hengist Member

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    I think this is a start. If we take your example, CG is 1 foot in front of the axle, ball is 5 feet from axle, let's use a downforce when level of 500 pounds at the ball. So 500 pounds times 5 feet = 2500 foot pounds torque at axle. That supports 2500 pounds of trailer weight 1 foot from axle. When you tilt the lever pivoting on axle, there is indeed a component of the force that wants to push forward (if we are lowering the lever) or backward (if we are raising it).

    As I recall, in our example, the downward force would be 500 pounds * cos (angle) where angle is measured from horizontal. Horizontal force is 500 * sin (angle). So let's take 10 degrees tilt, which is extreme. Downward then is 492 pounds and horizontal is 87 pounds.
     
  16. pvogel

    pvogel Member

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  17. Gwgan

    Gwgan Almost a wagon

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