Bosal Hitch Adapter Loosening

[ohmman]

My current hypothesis is that this is caused by using a weight distribution hitch. I don't blame Bosal or Tesla at all, though I would very much have liked some guidance on the use of WD (neither provides any).

WD hitches create a stiffness between the trailer and the tow vehicle through the use of torsion bars. Once the bars are locked in place, the trailer is no longer able to freely rotate on the hitch ball. Depending on the rating of the bars, there can be quite a bit of stiffness between the two vehicles. When the trailer and the tow vehicle are on different planes, such as with uneven pavement or dips in the roadway, a force is exerted by the bars into the tow vehicle. In fact, this is precisely how the WD hitch is supposed to work in order to push some of the weight off of the rear wheels and onto the front wheels. In a welded receiver solution, the force is transferred directly to the vehicle unibody or frame. But in our removable hitch solution, that force has to transfer through the hitch socket before making it into the vehicle.

Compare this with a weight bearing hitch. The trailer and tow vehicle are able to move independently of one another with relation to the planes on which they travel. There are forces pushing on the socket, but they are only the forces of the tongue as it travels. Any twisting will be completely relieved at the hitch ball.

This is admittedly just a hypothesis. I plan to propose this to Tesla, and send them my entire hitch apparatus, including the bar, once I remove it. Hopefully they can do a solid investigation into it. If indeed it appears that WD is causing this, they could address it as simply as adding a blurb to the towing section of their Model X guide. "Weight distribution hitches are not supported by the stock receiver."

All of that said, I still wouldn't tow a heavy vehicle with the stock hitch. Having three ball bearings holding my entire trailer in place no longer gives me peace of mind.

 

[ecarfan]

My current hypothesis is that this is caused by using a weight distribution hitch.

Interesting hypothesis. As I recall, @JimVandegriff recently checked his hitch and noted some play also. His trailer weight is similar to yours.

@jackbowers has not posted about having this issue, but then his trailer is about half the weight of your Airstream. I don't recall if he uses a weight distribution hitch or not.

You guys are the Model X trailer towing pioneers! Thanks for blazing a trail for us future X trailer towers.

 

[ohmman]

@jackbowers has not posted about having this issue, but then his trailer is about half the weight of your Airstream. I don't recall if he uses a weight distribution hitch or not.

If I recall correctly, he doesn't. I don't remember seeing one on the vehicle when I checked it out.

I would be curious to see how he was able to stay within the strict offset requirements of the Bosal hitch.

 

[mongo]

My current hypothesis is that this is caused by using a weight distribution hitch. I don't blame Bosal or Tesla at all, though I would very much have liked some guidance on the use of WD (neither provides any).

WD hitches create a stiffness between the trailer and the tow vehicle through the use of torsion bars. Once the bars are locked in place, the trailer is no longer able to freely rotate on the hitch ball. Depending on the rating of the bars, there can be quite a bit of stiffness between the two vehicles. When the trailer and the tow vehicle are on different planes, such as with uneven pavement or dips in the roadway, a force is exerted by the bars into the tow vehicle. In fact, this is precisely how the WD hitch is supposed to work in order to push some of the weight off of the rear wheels and onto the front wheels. In a welded receiver solution, the force is transferred directly to the vehicle unibody or frame. But in our removable hitch solution, that force has to transfer through the hitch socket before making it into the vehicle.

Compare this with a weight bearing hitch. The trailer and tow vehicle are able to move independently of one another with relation to the planes on which they travel. There are forces pushing on the socket, but they are only the forces of the tongue as it travels. Any twisting will be completely relieved at the hitch ball.

This is admittedly just a hypothesis. I plan to propose this to Tesla, and send them my entire hitch apparatus, including the bar, once I remove it. Hopefully they can do a solid investigation into it. If indeed it appears that WD is causing this, they could address it as simply as adding a blurb to the towing section of their Model X guide. "Weight distribution hitches are not supported by the stock receiver."

All of that said, I still wouldn't tow a heavy vehicle with the stock hitch. Having three ball bearings holding my entire trailer in place no longer gives me peace of mind.

The WD could be a major factor. Given the tight limits on the hitch ball location and bike carrier weight limits, the extra leverage of the WD hitch system may exceed the hitch design. Normal limit is 500 pounds at 8 inches from pin (13 ish from adapter attachment).

The normal setup has minimal upward loading on the hitch system (weight shift to front wheels/ net negative tongue weight). So if the system goes from a negative load state to positive often due to road conditions, the adapter will be wiggling around much more than a normal trailer (not sure if a normal setup with 10% tongue weight can go net negative).

Edit addition/ opinion:
Since the receiver is not a direct frame connection, I do not think it can be used with a WD system. The WD system applys all the torque/load to the adapter which has clearance to its mount and forces that connection to pivot. It also creates higher loads than it is designed for.

I think WD rated recievers call out that feature, but it would be helpful for Tesla to update the manual to specifically state yay or nay.

 

[idoco]

Video from etrailer on Bosal vertically detachable hitch.

1:08 in: "cannot work with a weight distribution system"

 

[Gwgan]

In the second video looking at the inserted hitch there is a lot of play around the arrowhread shaped piece. Could there have been something blocking the hitch from full insertion?

 

[ohmman]

In the second video looking at the inserted hitch there is a lot of play around the arrowhread shaped piece. Could there have been something blocking the hitch from full insertion?

That's what I thought with the original wiggle, but it doesn't appear to be the case with either hitch adapter. They will not snap into place if they aren't inserted all the way. The ball bearing at the bottom of the shaft is a trigger to release the internal spring loaded pin and eject the ring of ball bearings around the top. I believe it's more likely that there is deformation inside of the socket.

 

[ecarfan]

New Video from etrailer on Bosal vertically detachable hitch.
1:08 in: "cannot work with a weight distribution system"

Well that is interesting...and an odd way to phrase it. As @ohmman has shown, in "can work" but over time a problem develops.

 

[mongo]

Well that is interesting...and an odd way to phrase it. As @ohmman has shown, in "can work" but over time a problem develops.

Working for a while and working forever are two different design modes (sledge hammer vs cast iron tub, the tub can stop the hammer a few times, but it is going to loose).

I'm wondering if the binding that occurs in the Ws during turning is the force inducing the failure. A normal hitch setup would only produce a side load during a turn due to the CG of the load located in front of axle (same 500lb tongue weight limit).

A WD system binds the trailer to the receiver and so the adapter connection gets a lot more side torque placed on it. Each time the load shifts sides, the mechanism is accelerated across the gap and impacts the other side. This can slowly deform the metal, widening the gap, and allowing the next reversal to develop more energy before impact. So, over time, it gets worse, and the worse it gets, the faster it gets worse.

just a theory.

 

[jamtek]

Video from etrailer on Bosal vertically detachable hitch.

1:08 in: "cannot work with a weight distribution system"

In my mind this really begs the question, "Is it even necessary to use a weight distribution system with the Model X factory tow hitch installed?"

The Model X is a heavy vehicle, weighing about 5300 lbs and a GVWR of about 6700 lbs. As long as the tongue weight and tow capacity of 5000 lbs is never exceeded is weight distribution necessary??

Thoughts?

 

[ecarfan]

The Model X is a heavy vehicle, weighing about 5300 lbs and a GVWR of about 6700 lbs. As long as the tongue weight and tow capacity of 5000 lbs is never exceeded is weight distribution necessary

This has been extensively discussed in other Model X towing threads. Right now we don't have many data points.

@fortytwo tows a 1,725 lb (dry weight) Safari Caravans Alto trailer with no WD hitch. That is a very light 17 ft trailer, less than half the weight of a loaded X (with two people and whatever they put in the car)

@jackbowers tows a 2,300 lb (dry weight) Bowlus Road Chief with (it appears) no WD hitch. That trailer loaded is not much more than half the weight of a loaded X.

And then we have @ohmman and @JimVandegriff towing their 22 ft Airstream Sports which are approximately 3,600 lbs (dry weight). They are using WD hitches. That trailer loaded is getting up near the weight of the X tow vehicle.

 

[jamtek]

This has been extensively discussed in other Model X towing threads. Right now we don't have many data points.

@fortytwo tows a 1,725 lb (dry weight) Safari Caravans Alto trailer with no WD hitch. That is a very light 17 ft trailer, less than half the weight of a loaded X (with two people and whatever they put in the car)

@jackbowers tows a 2,300 lb (dry weight) Bowlus Road Chief with (it appears) no WD hitch. That trailer loaded is not much more than half the weight of a loaded X.

And then we have @ohmman and @JimVandegriff towing their 22 ft Airstream Sports which are approximately 3,600 lbs (dry weight). They are using WD hitches. That trailer loaded is getting up near the weight of the X tow vehicle.

Acknowledged. But the Airstream Sport 22 weighs about 3600 lbs with LP and batteries loaded. It has a GVWR of 4500 lbs so fully loaded with gear it will still be almost 1000 lbs lighter than a Model X. That is significantly lower than a 1:1 ratio. Most of the things I read say using a weight distribution hitch becomes more necessary the closer your trailer weight gets to being the same as your tow vehicle weight (1:1 ratio). You're right...we need more real world data.

When my Airstream Sport 22 arrives next month I will try and put this to a real world test and we will have more data points to consider.

 

[ohmman]

Acknowledged. But the Airstream Sport 22 weighs about 3600 lbs with LP and batteries loaded. It has a GVWR of 4500 lbs so fully loaded with gear it will still be almost 1000 lbs lighter than a Model X. That is significantly lower than a 1:1 ratio. Most of the things I read say using a weight distribution hitch becomes more necessary the closer your trailer weight gets to being the same as your tow vehicle weight (1:1 ratio). You're right...we need more real world data.

When my Airstream Sport 22 arrives next month I will try and put this to a real world test and we will have more data points to consider.

If you go to RV forums, you'll get quite a bit more data (opinions?) than you will here. I created this thread a while back if you're interested, and it generated some responses, but nothing like you'll read at Airforums or other RV forums.

Sway is a true concern regardless of steering and suspension considerations. I don't think you can do a real-world test that will simulate all conditions that might cause sway without a WD hitch. And, quite honestly, would you want to? That's the issue here, there aren't controlled studies done on this stuff. So much of it is personal anecdote.

If I could drive without weight distribution/sway control and ensure the safety of myself, my passengers, and other motorists on the roadway, I'd jump at it. It's easier to hitch/unhitch, and I wouldn't have to cringe when I go over bumps (although that'll change with my new receiver mount). In everything I've read, however, it seems like it's the safer of the two choices and that's why I'm pulling with it. I'm definitely interested to hear what you learn.

 

[ohmman]

I'd like to also add that I have lost faith in the stock hitch and wouldn't tow my Airstream with it whether or not I'm using weight distribution. I would feel comfortable with something in the sub-2500 lb, sub-250 tongue weight category probably, but not much more than that. That's just my personal opinion, though, and it's likely tainted by the experience I've had to date.

 

[jamtek]

I'd like to also add that I have lost faith in the stock hitch and wouldn't tow my Airstream with it whether or not I'm using weight distribution. I would feel comfortable with something in the sub-2500 lb, sub-250 tongue weight category probably, but not much more than that. That's just my personal opinion, though, and it's likely tainted by the experience I've had to date.

I appreciate hearing your experiences @ohmman. I will definitely keep the group posted with what I learn. I have a few inquiries pending with some industry experts so I'm anxious to hear their views on this.

My paramount concern is safety. Second I want to make sure the chassis, structural framework, drive train etc of my X is not subject to unacceptable loads.

 

[mongo]

If you go to RV forums, you'll get quite a bit more data (opinions?) than you will here. I created this thread a while back if you're interested, and it generated some responses, but nothing like you'll read at Airforums or other RV forums.

Sway is a true concern regardless of steering and suspension considerations. I don't think you can do a real-world test that will simulate all conditions that might cause sway without a WD hitch. And, quite honestly, would you want to? That's the issue here, there aren't controlled studies done on this stuff. So much of it is personal anecdote.

If I could drive without weight distribution/sway control and ensure the safety of myself, my passengers, and other motorists on the roadway, I'd jump at it. It's easier to hitch/unhitch, and I wouldn't have to cringe when I go over bumps (although that'll change with my new receiver mount). In everything I've read, however, it seems like it's the safer of the two choices and that's why I'm pulling with it. I'm definitely interested to hear what you learn.

Having been in a conversion van hauling a 27' fixed keel sailboat on a converted mobile home chassis trailer, WD definitely increases control/ confidence (for grins, watch a front wheel drive minivan pull a boat up a launch ramp). I would be interested to see some test results from Tesla on their anti-sway stability control. However, for a lighter load with a large cross section, an anti-sway hitch/ receiver combo would definitely increase control in cross wind or semi passing situations.

 

[qadaemon]

Hey @ohmman the draw-tite says "Not rated for use with weight distribution systems". Are you ditching your current draw bar or are you going to use it without the WD bars?

 

[ohmman]

The Draw-Tite is adopting guidelines from the vehicle manufacturer (Tesla). Since Tesla hasn't given WD guidance, Draw-Tite cannot rate for it. I plan to tow with my properly adjusted torsion bars and careful attention to the rig.

 

[qadaemon]

The Draw-Tite is adopting guidelines from the vehicle manufacturer (Tesla). Since Tesla hasn't given WD guidance, Draw-Tite cannot rate for it. I plan to tow with my properly adjusted torsion bars and careful attention to the rig.

Oh ok, I was reading their docs as though they did some sort of testing. I'm ordering one but very interested in your experiences once you get it up and going if you don't mind sharing.

 

[steilkurve]

New model X owner who just upgraded from an S. Many reasons for the change, one of which was the ability to hitch bikes and snow gear in the back. Now that I have the car, I’ve been toying around with the idea of towing a trailer, a 16’ Airstream. This discussion has been quite informative, being a novice at trailers. Questions for the experts here. Seeing as WD seems to be a no go and that towing a 22’ seems to be challenging without WD, would a 16’ Airstream be much easier to tow? Would the shorter by 6’ and lighter by what 800 pounds or so make a big difference?