Tow Hitch/7-Pin Connector/Brake Controller

Generally I like to DIY whatever I can because I like working in my workshop and find it to be a great stress-reliever from my work life.

After looking into DIY'ing a receiver hitch, brake controller, 7-pin connector, and the associated wiring, I decided that it was best and safest to have a professional do the installation. There were too many stories about problems wiring in brake controllers, LED trailer lights, signal multiplexing, etc. and was worried that I'd end up with an install that didn't fully work properly.

So I had a local trailer/hitch shop do the install and they recommended a Teknosha Prodigy P2 brake controller along with a welded/bolted 10,000 lb receiver hitch.

For my first tow, I am renting a U-Haul 6x12 trailer on Friday to get some experience towing something around and so I can start to learn how to back up with a trailer.

Then in two weeks I am renting a 22' Forest River Wolfpup Model 16PF travel trailer (loaded tow weight around 4400 lbs with 400 lb tongue weight) to stay at Buttonwillow Racepark about 140 miles north of LA while I auto race for a 3-day weekend. I will be using the trailer owners weight distributing hitch with sway control.

I am looking forward to see how the E53 tows and handles that kind of weight on the freeway and especially over the Grapevine/Tejon Pass north of LA where Interstate 5 goes from 1,360 ft in San Clarita to 4,120 ft at the top of the pass and then down a fairly steep decent into the Central Valley ending at 1,500 ft.

If all goes well with towing on the trip to the Central Valley, it is highly likely that I will purchase a similar 22'/5000 lb max weight travel trailer to use for traveling around the country to auto race and for camping/hiking. Previously, we've rented various Class C RV's for camping/hiking trips and I would really like to have a rig of our own.

Wow- so you didn’t use the OE Westfalia-made E53-specific hitch? Did you use the OE wiring harness and module ?

Love to see how the hitch is mounted.. the OE hitch is Pretty well engineered.

I'm anxious to hear how the 3.0L does pulling the 4400 lb trailer up the Grapevine. That will be 10,000 lbs trying to go the opposite direction somewhere around Gorman.

I have to second this. My son and I pulled an OE hitch off an E53 parts car we purchased and I was very impressed with the engineering, design and integration.

Thanks for the comments!

I'll have to see about removing the rear bumper cover to take some photos of the hitch mounting points. If I had to guess, I would say that the hitch most likely mounts like the DrawTite aftermarket hitches to the rear subframe bumper mounts.

The portion of the hitch that goes under the car towards the differential is welded to the rear subframe instead of bolting to a rear crossmember like the DrawTite hitch.

The installer did use an OEM 7-pin connector, harness, and electronic module which they interfaced with the external trailer brake controller and added LED trailer light compatibility.

I'm all set to pick up the U-Haul trailer tomorrow to practice driving and backing. Then I'll let you know how it tows the travel trailer in a couple of weeks.

Thanks to the great info in here I'm happy to report Swampy and I will be joining the cool kids club :cool:

https://i.imgur.com/TMyjVqF.jpg

While we wait I'm hoping to score a decent used set of something in a 265/70/17 size. We'll see if I get lucky

I have a 2001/3.0 and had no problems towing 3 tons (car on deck trailer) over mountain passes with up to 10% gradient at it steepest, without being too much of a PITA to other motorists ;)


I have no supporting upgrades such as air suspension, heavier springs, or equalizer hitch. Just be sure to balance the load properly.


cheers

thStone, great job on the X5 and it looks awesome. I'm in the process of acquiring an electric brake controller and adding it to my X5. I plan to eventually start making the stock looking SUV into one of these more outdoor adventuring ones. I have some nice AT tires on it now and the 7 pin Hitch installed. I want to add the LED light bar or squared light on the roof rack as well as a few more things here and there as time goes on.

Lift spacer
 

Thstone, have you seen this? https://www.youtube.com/watch?v=aELNPl5Qrmw

** Towing Update **

Sorry for the lengthy delay in posting! The biotech business that I run has been super busy and I’ve been car racing a lot.

At this point, I have towed on four separate trips using two different trailers for a total of 1,440 miles. The shortest trip was 230 miles (round trip) and the longest was 750 miles (round trip).

The trailers each weighed around 4400 lbs as towed (including fresh water, food, and gear). Both trailers have empty weights around 3800 lbs and GVWR’s (max weight) around 5,000 lbs. As such, both trailers are well within the X5 tow rating of 6,000 lbs.

Payload weight and hitch (or tongue) weight is also a consideration in towing. The hitch weight of each of the trailers is about 450 lbs which is well within the X5 rating of 600 lbs.

In terms of payload, the X5 carries 450 lbs hitch weight + 190 lbs for me + 110 lbs for my wife + another 100 lbs of gear for a total of 850 lbs. This is well within the X5 payload capacity of 1,345 lbs.

Combining the trailer weight (4400 lbs) with the X5 weight (5240 lbs), there is a total of 9,640 lbs (nearly 5 tons!) that we’re driving around.

With all of that weight, the 3.0L E53 X5 does a pretty good job of accelerating and getting up the hills. On a level road, the engine is working to get up to my typical highway cruising speed of 60-65 mph, but not overly hard. However, the low torque rating for the 3.0L engine becomes obvious as soon as an uphill grade is encountered causing the transmission to downshift a gear to allow the engine maintain an appropriate rpm. A big plus here is that the transmission shifts seamlessly and never hunts back and forth between gears.

Continued next post...