Towing question, have read all the threads

[JCL]

Originally Posted by Karl w/a K

mfiver,
I'm been doing a lot of hitch research. I'm trying to figure out if the bumper supports are shock absorbing or static. I ask because the BMW OEM hitch has you remove the bumper supports, add the hitch box section, then add the tube looking brackets on top. Basically throwing away the original supports. If the original supports are static, I have no problem replacing them with the steel sections. If the originals are dynamic, I feel like I'm loosing some of my bumpers ability to absorb 5mph hits. Does this question make any sense? Any help is appreciated.
(2000 X5 4.4)
Thanks

Good question. The original bumper mounting method is that the plastic bumper is attached to a metal carrier, which hangs on the two collapsible struts. They are shock absorbing. The struts mount to the rear sheet metal with five (IIRC) bolts, and run fore/aft inside a box section sheet metal structure.

Aftermarket hitches generally mount to the same five bolts, which are just bolted through the sheet metal, there is no real structure there. Yes, in that case, you retain the shock absorbing struts for the 5 mph bumper.

The OEM hitch replaces the two collapsible struts with fixed supports, running fore/aft. Those supports are attached at the front to the box section they run inside of, sort of like a formed frame rail in concept. That is how the load is transferred to the vehicle structure, it is more important than the five bolts IMO. The hitch receiver then bolts to the five bolts (on each side), but it is now tied in to the body structure by more than the rear sheet metal. A new (heavier) carrier is mounted inside the bumper, as the bumper needs to be rigid enough to take the minor bump it is rated for (5 mph or whatever the standard is).

Yes, you lose the collapsible struts. But realize that the stock bumper would move in and out on the struts. There is now a hitch receiver frame in the space the bumper would have collapsed in to, and a protruding hitch receiver to take the first impact. I don't think you are losing anything in terms of bumper function. The law calls for a 5 mph impact without damage, but it doesn't require the shock absorbers. A heavier structure is another way of doing it, but it would be more expensive for BMW to make them all that way from the factory, the shock absorbers are cheaper.

And, when all is said and done, unless the rear impact is evenly applied you will probably get damage to the plastic anyway, as bbh03 says.

Good luck.

[davidachoi]

I've been looking for this exact subject for the past 6 weeks and finally found it. I just bought a 27' 1976 Airstream trailer and it's GVVR is 6200 lbs. mfiver, how heavy is your rig loaded? What type of tow equipment do you have to pull that load? And did you say you didn't have any sway problems? How fast did you go? I was looking at the specs for the Prodigy brake controller http://www.reese-hitches.com/product...HH_39519,90185
and it says that it's not recommended with the X5. Any idea why not? And what exactly is a brake controller? It controls the brake system? That's assuming that the trailer comes with brakes? My AS guy said my trailer only comes with emergency break away brakes. Do I have to buy additional brakes?

[JCL]

Originally Posted by davidachoi

I've been looking for this exact subject for the past 6 weeks and finally found it. I just bought a 27' 1976 Airstream trailer and it's GVVR is 6200 lbs. mfiver, how heavy is your rig loaded? What type of tow equipment do you have to pull that load? And did you say you didn't have any sway problems? How fast did you go? I was looking at the specs for the Prodigy brake controller http://www.reese-hitches.com/product...HH_39519,90185
and it says that it's not recommended with the X5. Any idea why not? And what exactly is a brake controller? It controls the brake system? That's assuming that the trailer comes with brakes? My AS guy said my trailer only comes with emergency break away brakes. Do I have to buy additional brakes?

There are lots of posts on trailers and brakes, but I think you may need some basic information on towing, brake controllers, weight-distributing hitches, etc, to make sense of them. That information is not specific to the X5, it applies to all tow vehicles.

There are articles on the X5 World home page on installing brake controllers. What a trailer brake controller does is pick up a braking signal from the tow vehicle, and then activate the trailer brakes. The signal can come from the X5 brake lights, or a second brake light switch mounted on the brake pedal. It can also come from a switch attached to the top of the brake pedal, essentially a switch that you step on to push the brake pedal. Yes, you will need active trailer brakes for that weight of trailer on the X5. They can be surge brakes (which self-activate when the trailer feels the tow vehicle slowing) or they can be electrically activated.

[davidachoi]

Thanks, that helps. For the active brake system for the trailer itself, does that have to be installed separately? Maybe that's a trailer question.

[JCL]

Originally Posted by davidachoi

Thanks, that helps. For the active brake system for the trailer itself, does that have to be installed separately? Maybe that's a trailer question.

That is a job for your trailer supplier or a shop that works on trailers.

[bbh03]

Having installed the OEM hitch, I believe they are static (using your terminology). The ones removed are typical shock absorbing types and they are replaced with solid steel pieces that come with the hitch. That said, I believe the plastic bumper would probably crack regardless.

I have been towing a 20' vnose enclosed with a loaded weight of right about at 6000 lbs with my 4.4 for about a year now. I am using a load distributing hitch, Prodigy and have been loading race cars with engine to the rear to try and maintain proper tongue weight. That said, I do have moments when I feel the rig is not so stable, especially around 70 mph. Plus, the car will vibrate at those speeds for a reason unknown to me.

As impressed as I am with this little car's ability to tow, I will likely upgrade to a 3/4 ton truck for towing anyway 1) because I'd like to be able to throw more equipment in without worrying and 2) tow a larger trailer in the near future (20' vnose is a tight squeeze for an E36). I'm not willing to go beyond the mfg's rated tow capacity for both safety and liability reasons.

[frayed]

Old thread. . . fyi I went with a Prodigy controller, and have racked up some miles with an open steel trailer + M3 track car = 5000+lbs. No problems. Tows like a beast. Also been towing my 23' fishing boat on a trailer with no brakes. Pulls hard to 75mph then drag takes over.

Have to use manual shift mode in hilly terrain though.

All in all, great tow machine, though I'm a bit concerned about long term durability, so I'm happy to have the 100k mile/2011 warranty!

Short wheelbase make backing up boat down ramp a breeze, too.

[tetice]

Originally Posted by frayed

Old thread. . . fyi I went with a Prodigy controller, and have racked up some miles with an open steel trailer + M3 track car = 5000+lbs. No problems. Tows like a beast. Also been towing my 23' fishing boat on a trailer with no brakes. Pulls hard to 75mph then drag takes over.

Have to use manual shift mode in hilly terrain though.

All in all, great tow machine, though I'm a bit concerned about long term durability, so I'm happy to have the 100k mile/2011 warranty!

Short wheelbase make backing up boat down ramp a breeze, too.

I knew it was an old thread but there aren't too many pulling the kind of load you show in the photos... so you abandoned the 24' enclosed trailer?? That's the angle I was most interested in. Was it too much for the X5?

I currently have an open trailer and it pulls like a dream. I have surge brakes and that avoids the need for a controller - seems to work fine other than a klunk when they engage and when they release. A friend riding with me to a race commented after a few hundred miles that he knew why it made that sound. It was to let you know there was a trailer back there otherwise you would forget. He was used to pulling an enclosed trailer with a 2500 diesel dually truck.

TIA

PS I've also pulled a 20 foot i/o runabout boat with no brakes and a 22 foot poontoon also with no brakes. Both of those are a bit more of a challenge than the dual axle open car trailer. I agree on the backing.

[frayed]

naw, wasn't me with the enclosed trailer. . . I ended up going open as I just didn't want to deal wiht the tying down the track car in a tight enclosed trailer. good luck though

[tetice]

Originally Posted by frayed

naw, wasn't me with the enclosed trailer. . . I ended up going open as I just didn't want to deal wiht the tying down the track car in a tight enclosed trailer. good luck though

Oops, sorry that was surgeondress who had the enclosed trailer.

Tom Tice
'93 325iS SE36 #110
'98 M3/4
'02 X5 4.4