Towing with my X5

[JCL]

Any hitch will apply a bending (twisting) moment to the receiver, based on the trailer tongue weight and the dynamic loads caused by accelerating and braking.

If you are buying an alternate hitch (drawbar) to that sold by BMW, you should be aware of the BMW specs for that hitch. The BMW spec for the ball location is no more than 8" horizontally from the pin that the hitch drawbar is secured to the receiver with. There is a limit of 12" vertically from the top of the receiver to the base of the hitch ball.

Exceeding those specifications (ie more vertical drop, or more horizontal extension) will stress the receiver beyond what it was designed for. I am not suggesting that you cannot go over those limits for very light trailers, but you do so at your own risk.

[Tags]

We just bought our X5 and we're planning to use it to tow our Malibu Response skiboat. It weighs about 3.5T all up so it will be interesting to see how the 3.0ltr copes. Based on advice from others it should be ok.

Does anyone else have experience with towing a 3.5T or heavier boat?

Cheers,

[JCL]

Originally Posted by Tags

Does anyone else have experience with towing a 3.5T or heavier boat?

Lots of experiences on the board, do a quick search on tow and boat. Have a look at this post:

Xoutpost.com - View Single Post - X5 Pulling 5900# Boat . . . Awesome!!

[jblumhorst]

Originally Posted by JCL

Any hitch will apply a bending (twisting) moment to the receiver, based on the trailer tongue weight and the dynamic loads caused by accelerating and braking.

If you are buying an alternate hitch (drawbar) to that sold by BMW, you should be aware of the BMW specs for that hitch. The BMW spec for the ball location is no more than 8" horizontally from the pin that the hitch drawbar is secured to the receiver with. There is a limit of 12" vertically from the top of the receiver to the base of the hitch ball.

Exceeding those specifications (ie more vertical drop, or more horizontal extension) will stress the receiver beyond what it was designed for. I am not suggesting that you cannot go over those limits for very light trailers, but you do so at your own risk.

I've just taken delivery of a new 2009 X5 35d, with the OEM receiver hitch installed. The wiring includes a module to change shifting points and anti-sway programming for the AWD. We also installed a Tekonsha Brake Primus controller that I've been using for the past two years.

1> Does anybody know what the GCWR is for the X5? I contacted BMW customer support last week , and they haven't got an answer yet.

2>As long as the ball is within 12" vertical and 8" from the pin can I use a weight distribution hitch?

3> The "instruction" sheet that came with the receiver hitch cautions against using a weight distribution setup. Why?

I've using Weight Distribution hitches for years, (with another vehicle that had self levelling suspension). Without a WD hitch, it's impossible to get over 10% tongue weight on a 6000 pound trailer.

To prevent sway, you really want 12-15% of trailer weight on the tongue. Sure, the car has anti-sway traction control, but why let sway get initiated in the first place?

I understand the physics of a WD hitch transferring load to the front axle and trailer axle away from the rear tow vehicle axle. I don't see how it would damage or confuse the X5.... maybe it's because the spring bars create dynamic load changes, (and is not static like passengers or luggage)?

I really would like to be able to use a WD hitch, but I don't want to mess up the fancy suspension.

J B
2009 X5 35d
Currently towing a 16 foot travel trailer but hoping to trade up to something larger

[JCL]

Originally Posted by jblumhorst

I've just taken delivery of a new 2009 X5 35d, with the OEM receiver hitch installed. The wiring includes a module to change shifting points and anti-sway programming for the AWD. We also installed a Tekonsha Brake Primus controller that I've been using for the past two years.

1> Does anybody know what the GCWR is for the X5? I contacted BMW customer support last week , and they haven't got an answer yet.

2>As long as the ball is within 12" vertical and 8" from the pin can I use a weight distribution hitch?

3> The "instruction" sheet that came with the receiver hitch cautions against using a weight distribution setup. Why?

I've using Weight Distribution hitches for years, (with another vehicle that had self levelling suspension). Without a WD hitch, it's impossible to get over 10% tongue weight on a 6000 pound trailer.

To prevent sway, you really want 12-15% of trailer weight on the tongue. Sure, the car has anti-sway traction control, but why let sway get initiated in the first place?

I understand the physics of a WD hitch transferring load to the front axle and trailer axle away from the rear tow vehicle axle. I don't see how it would damage or confuse the X5.... maybe it's because the spring bars create dynamic load changes, (and is not static like passengers or luggage)?

I really would like to be able to use a WD hitch, but I don't want to mess up the fancy suspension.

Well, here goes. Point form responses.

I have never installed a hitch or towed with an E70. All my experience is with an E53, and many non-BMW vehicles. However, I think you can likely extrapolate many of the experiences posted about on this board. All the following applies to an E53. Note that the E70 really isn't that different from a design perspective. The E53 had sway control in the DSC, and I don't know that the E70 version would be very different. I haven't touched the 35d issue, but if you have the brake controller installed you have addressed what my largest concern would be.

I haven't seen GCWR figures published, but they may exist. They are a much better form of determining towing limits, but since BMW really isn't in the towing business, they just don't go down that road AFAIK. They do say in some publications to reduce towing limits by the amount of load in your vehicle, so they have the concept in mind, but it is just that they don't spend a lot of time thinking about towing limits. That is just my opinion.

I well remember the 8" horizontal limit in the above post, but I don't know why I typed 12" vertical. Let's put it down to a brain fart, and it was probably midnight. The E53 limit is 5.5" vertical (see attached jpg). You can check and see if the E70 is much different. This sticker came in my E53 hitch kit.

BMW doesn't recommend weight distributing hitches. In my opinion, it is because there are too many variables involved in the use of such devices and BMW can't be responsible for the actions of owners who can barely remember to install brakes over 1600 lbs trailer weight, let alone adjust tongue weight. The safest thing for BMW (and their lawyers) is to recommend that you don't go there. I don't see the impact on the rear suspension as being a factor in any way. I would have no reluctance to install a WD hitch myself, if I wanted to tow something heavy enough. That said, I trust my ability to determine tongue load, and so on. Use at your own risk. I'd do it, but that is me. Just for fun, I have included a picture of long term poster withidl's 2001 4.4 E53, with an 8300+ lb Airstream being towed with a Hensley Arrow WD hitch, with sway control built into the hitch interface. Reportedly tens of thousands of miles pulling the trailer without any problem, rear air suspension, 900 lbs tongue weight. As Nike would say, just do it. Do a search on withidl's posts if you would like more info.

Hope that helps. The real issue is that the X5 is far better at towing than BMW are at defining towing procedures. That doesn't mean that the vehicle can't do it, just that you tend to be on your own to a certain extent. Regular inspection of the hitch, adjustment of the WD device, and driving with due care and attention are part of the formula for success.

Jeff

[X5Kiwi]

I tow my boat often with my 4.4 X5, trailer doesn't have any additional braking but I have no shortage of pulling or stopping power.

[jblumhorst]

Thanks for the reply, Jeff. It helped me think through some of the data I've already got. I always think more clearly when I collaborate with someone.... see what you think about this:

Below are the specs on my X5 (I believe the rear GAWR is 300 pounds higher bc of the rear seat row)

GVWR 6614
GAWR F 3,064
GAWR R 3,869
curbweight 5,225
payload 1,290

Here's a link to a copy of the owner guidelines that came with the Reciver Hitch installation instructions:
Picasa Web Albums - Judith - 2009 BMW X5 (...


The guidelines state that the 6000 gross trailer weight " is based on a standard equipped vehicle with driver. Additional pssengers and/or cargo will reduce maximum vehicle trailer/ratings." So, assuming the driver weighs 250 pounds and the curb weight is 5225, then an estimate of GCWR might be = 250 + 5225 + 6000 = 11,475.

A weight distribution hitch shifts the load off the vehicle's rear axle onto the front and trailer axis -- and the torque is transmitted from the receiver via the hitch attachments to the frame or unibody. Interestingly, the draw bar specified for the receiver allows almost no vertical drop, and a modest rise.

It's late, and I'm no engineer, but I think it's valid to assume the engineers only tested for 600 x 8/12 = 400 ft-pounds of torque (8" from the pin, almost straight in line vertically... )

... so can I assume that using a weight distribution hitch, even with a short draw bar with no drop, for a trailer with a tongue weight of greater than 600 pounds might very well exceed the structural limits of the receiver hitch and/or attachment points on the X5????

.... I gotta think about this some more tomorrow....

JB

[JCL]

Well, I am a mechanical engineer (registered P.Eng.), but let's leave that aside since the following is based on judgement, not calculations.

I would go with the extension/drop limits of the standard E70 hitch, which you have, instead of the E53 version. That probably gives you a reasonably level trailer in any case.

I don't think that the engineers tested for any of your scenarios; I think that they calculated normal static loads (no WD hitch) and applied typical safety factors, and then left it at that. You are going an order of magnitude deeper into the calculation than the poor sap who wrote the manual, IMO.

Now, here is the key point. I haven't designed or analyzed WD hitches, But intuitively, doesn't the weight distributing feature naturally counteract the bending moment of the static load on the hitch ball (since it reduces the weight on the rear axle, and doesn't increase it)? Think about it; the static load pushes the rear of the X5 down, and the WD hitch lifts it. Opposite effects. They tend to offset each other, not aggregate. There is a stress point at the hitch ball where the WD hitch has the ball and the WD levers attached, but that is part of the WD feature. The 2" square receiver and the part attached to the vehicle sees the net effect, it seems to me.

So, given all of the above, and what I know about the sturdiness of the BMW hitch, I would just do it. But again, that is just me. See if you agree with the above, though.

[we350z]

wow - e53 IS very capable towing machine. I know I exceeded 6,000 lbs. and I had the X packed to the gills including my 300ZX which was packed to the gills with crap.