Quote:
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