BMW X5d and Weight Distributing Hitch

[PKI]

Towing stability analysis uses trailer weight, tongue weight and also speed in the consideration. Less tongue weight would require a slower travel speed. Might just be possible that folks towed at 45 or 50 mph at the time your trailer was built. Pat

[bono]

I agree with PKI. Being from Europe, I am ok with towing at 50 mph, which is 80 km/h, a common speed limit when towing. This is one of the reasons, why European trailers are lighter on tongue.

[dkottum]

No kidding, these days on the interstate at 65 mph or so everything on the road passes us. Even a four-wheeler driving alongside in the ditch one time.

This is a generation in a hurry.

[59ORLander]

Well, we have ripped out our black tank and toilet (in lieu of going the natural porta potty route) from the trailer's back end, and are planning a fresh water tank to go in under the front end shelf (behind the new pullout couch) so this weight distribution might just work perfectly soon

[jcl]

Originally Posted by 59ORLander

Hmm..yeah that's a good point. It makes me wonder, though, why the original factory spec was 3850 lbs total and the tongue weight was 250 lbs, if I remember correctly?

Apart from the towing speed issue, which is very relevant, there is another factor that hasn't been raised. It isn't just about the weight distribution front/rear (resulting in xx tongue weight) but about the distribution of significant masses relative to the distance to the axles. Two otherwise identical trailers at 4000 lbs, with 10% tongue weight, and the same overall length and axle position, just as an example) can have very different towing stability characteristics due to that weight distribution. If trailer A has the weight concentrated more over the axles, it will have a lower moment of inertia than trailer B, which could have significant weights at each end of the trailer (but the same resulting tongue weight). For a quick demonstration of the effects of moment of inertia, go on a playground merry go round, spin up to speed, and then alternately lean in to the centre and lean out. Your rotational speed will change. Or watch a figure skater tuck their arms in to their body to spin faster. This rotational inertia is a prime contributor to sway, as there is a pendulum at work.

Euro trailers typically tow at lower speeds, and have less tongue weight, but they also try to have all of the mass concentrated over the axles. Our 10-15% tongue weight rule is for typical North American layouts, which often have significant weights at the extremities, due to valuing floor plan convenience over towing performance.

Jeff

[AS_X5]

For what it's worth, my wife and I spent four months last year touring the national parks in our 2014 23FB with 2013 X5 TV, and it could not have gone better. The X5 (gas) was able to handle anything! Boy did we get weird looks from those with 3/4 ton pickups though. Peppered with questions at every gas stop, which got a little old.

We just traded up to a new lease on a 2016 X5d turbodiesel, and the dealer installed a new-fangled hitch (Invisihitch?) instead of the previous standard 2" square receiver. It's rated to 6,000#, with 600# tongue weight. However, the ball mount does not accommodate weight distribution system (WDS/sway control). Looking at an adapter plate that turns it into a standard 2" receiver so we can use the old ball mount and WDS ball.

New and old ball mounts:
https://www.dropbox.com/s/xpjx1q3w5f...Hitch.JPG?dl=0

Proposed adapter plate:
http://www.reese-hitches.com/product...r_Tube,2201172

Tried towing without WDS once and it was unstable at highway speeds.

So, to all those who want to tow with German engineering, I say go for it. Once I figure out the ball mount adapter issue with the new X5 hitch I'll post an update.

[PKI]

Originally Posted by AS_X5

-- snip -- lease on a 2016 X5d turbodiesel, and the dealer installed a new-fangled hitch (Invisihitch?) -- snip -- rated to 6,000#, with 600# tongue weight. -- snip -- does not accommodate weight distribution system (WDS/sway control). Looking at an adapter plate that turns it into a standard 2" receiver so we can use the old ball mount and WDS ball. -- snip --

You may have a problem - note the distance from the plate bolting surface to the ball center line. It is a very tight configuration. Then calculate the distance the WDH ball will be from the plate surface when the adapter and WDH are installed. My guess is that it is about 12in more than the OEM location. Every inch added increases the lever arm and therefore the loading that is placed on the ball mount connection to the hitch cross member.

Now, you may not have a problem, if the connection design is over engineered and over built. That is not likely, but maybe.

Suggest you see if the connection is bolted or welded to brackets welded to the cross-member. If it is bolted, you can have an adapter constructed that locates the 2x2 receiver under the vehicle and with a shorter lever arm. The intent would be to keep the ball as close to the bumper as possible while still having enough clearance for the trailer tongue when making a tight turn. Note that the hole which locates the WDH ball mount in the receiver can often be moved to a location on the shank that reduces the lever on the assembly. Same concern with turning clearance applies.

You may be better off to take the X5 to a hitch shop and have a Curt or Draw-Tite hitch with a standard 2x2 receiver installed in place of the OEM hitch. Would cost about $850 +/- $250. Not sure how much the change would impact the end of lease residual value. Might require the OEM to be replaced.

Interested to hear how this works out for you. Any chance you have run your prior rig across a CAT scales. We are challenged to manage the 600# tongue weight limitation and would expect that might be an issue for you as well.

Good luck with your investigation. Pat

[AS_X5]

Pat, thanks again for the great advice.

Clearly it's not as simple as fitting an adapter, so I'll have to take it to a shop and see if they can do what you say. If it doesn't work out I'll get a real hitch installed.

The only reason I'm trying to make this work is that they included the $1500 BMW hitch and installation in the price of the car for my lease, which means I barely paid for it. I'll have to go back to them and convince them to take a significant loss, buy a Curt unit, and install it. With all they've put me through I have no problem forcing that through - maybe that will make their engineers in Munich take notice of our real towing requirements.

The one unanswered question is whether the new X5s do indeed come with some kind of unibody weight distribution that negates the need for aftermarket. But I doubt it.

Thanks again!

Tim

[AS_X5]

Also, though I too am concerned about tongue weight being over 600#, please note that our AS has the bedroom and storage in the rear. Apparently this was different for other 23FBs. It's listed at 457# tonge weight with full propane, so we might be fine.

[bono]

Folks at the dealership would not care about your issues. For sure nobody in Munich would care either. Re Curt hitch - check the design before going any further whether it makes sense to install this with intention to use weight distribution hitch. The Curt hitch for E70 does not require bumper cut as the OE hitch requires, but it has longer drop plates which even in the OE hitch are problematic when using WDS. Hence, the OE hitch needs to be reinforced. If F15 Curt design is similar, using WDS may cause you troubles.

[PKI]

Originally Posted by AS_X5

Also, though I too am concerned about tongue weight being over 600#, please note that our AS has the bedroom and storage in the rear. Apparently this was different for other 23FBs. It's listed at 457# tonge weight with full propane, so we might be fine.

Are you sure you have a 23FB. Bed in back would be a D model. FB has the bed in front with the Pano window and the toilet/shower in the back of the trailer. D has a heavier hitch weight. FB has a 457# dry weight and that is supposed to include propane, but not fresh water. It also does not include the hitch and that should be part of the tongue weight on the BMW as well, due to the hitch restrictions. Gets to 600 quick. If you reinforce then lots of options open up. However, with a leased vehicle, reinforcing is not a good idea. Pack light. Move heavy items to the center of the coach. Use as little WD as possible and bias the tow vehicle load forward as much as possible to help return weight to the front axle so you can minimize to WD.

The stability control offered for most vehicles operates the TV brakes and suspension and torque vectoring on the BMW to maintain direction. That does not do much for the coach. Some day we will see electronic sway control that is integrated between the TV and TT. There is TT control on some new trailers, but it's not a normal option. Give it a few years and we'll see more.

Travel safe. PAt