DIY- Trailer hitch

[Kracken]

I cant believe a european car mfg doesnt offer a plug and play towing wiring harness as much as they tow things over there...even my old 2002 acura had a towing accy connector pre-wired into the car's harness. All I had to do was buy and wire up the trailer side connector and click it in to the car side oem connector & just like that..it was done. Clean, with no worries about about warning lights, etc

Sold the acura and still have a bike trailer that hasnt had much use since. Guess I'll install a new hitch on wifey's acura now instead of the 1er...

[pj.rodriguez]

Originally Posted by Kracken

I cant believe a european car mfg doesnt offer a plug and play towing wiring harness as much as they tow things over there...even my old 2002 acura had a towing accy connector pre-wired into the car's harness. All I had to do was buy and wire up the trailer side connector and click it in to the car side oem connector & just like that..it was done. Clean, with no worries about about warning lights, etc

Sold the acura and still have a bike trailer that hasnt had much use since. Guess I'll install a new hitch on wifey's acura now instead of the 1er...

Alternatively, you can get the BMW rear bike rack. I have it and its awesome.

[JimD]

I haven't put a hitch on my convertible but I might in the future. We have two 128i verts in the family and both of us like ours and don't want to change. We also have a 2006 Suzuki SUV that does our towing. But the new house has more limited parking and a boat slip in the back so that towing duty will be going away. The vert should handle a little utility trailer.

Anyway, the zuk also lacked a plug in for the trailer wiring as have several cars I've owned. When you can find the plug in harness, it is not always reasonably priced. What you need to know is a location you can find the necessary wires. Even better is to know which color does what. I had to hunt around on the zuk and was still done in a few hours. With a voltage tester you can put on the signal you are looking for and probe until you find it. Wires normally come down one side of the car or the other. My guess is removal of the plastic sides in the back will reveal them.

With a little time and the converter (less than $20) you can normally wire things up. That shouldn't throw any codes but if it does they are easily reset (I prefer Torque but any decent OBDII code reader will do it).

[eeghie]

Originally Posted by Kracken

I cant believe a european car mfg doesnt offer a plug and play towing wiring harness as much as they tow things over there...

they do, you just have to order from Europe: 71602156300

RealOEM link

[c0zgrove]

How did you guys run the trailer wires to the outside of the car?

[horsepower_and_hounds]

I installed one last year on my 128 and it has been great. Only one issue that bugs me is when you run the car hard the exhaust moves back and rubs against the hitch. When cold there is a 11mm gap but when the exhaust heats up and the car is moving it moves back and rubs against the hitch. I was thinking of taking a grinder to the exhaust rib like "FactorX81" did but am just wondering if I have another issue or something loose in the exhaust system. Any ideas...11mm is a lot of movement? The hitch is installed per the manufacturer on the outside of the bumper brackets....

Cold:



Hot and parked:

[UR25IO]

hey guys will the hitch interfere with reversing sensors?

[horsepower_and_hounds]

So I measured it cold then warm at the time of interference.....it moves 11mm then rides on the hitch. Is that normal? Is there a slip joint or anything that can be adjusted to pull the exhaust forward?

[JimD]

I don't think you can safely move your exhaust away from the hitch by any reasonable measures. I looked up the thermal coefficient of expansion of 304SS. it is 17.3 x 10 to the negative 6th power meters per meter per degree Kelvin. I think better in SAE where the equivalent is 9.6 times 10 to the negative sixth inches per inch per degree farenheit. If I assume the exhaust is about 300 degrees F and the exhaust system is around 140 inches long I get about your amount of movement. My assumptions are rough and undoubtedly not exactly correct but the goal in this sort of a calculation is to see if you can get in the ballpark with something that is potentially reasonable. I would say this passes that test. In other words, 11mm could just be thermal expansion of the exhaust system.

To allow for that expansion the exhaust hangs on rubber hangers that have a lot of flexibility. If we take away that flexibility, we will bind somewhere else.

If the hitch is in the way and removing a little metal solves that, it is what I would do.

[horsepower_and_hounds]

thanks...will probably be grinding away at the tab a bit where there is contact to stop the loud rattle....it is quite annoying.

Thought about putting some kind of buffer there but it would not last long ai am sure.....

[FactorX81]

Originally Posted by JimD

I don't think you can safely move your exhaust away from the hitch by any reasonable measures. I looked up the thermal coefficient of expansion of 304SS. it is 17.3 x 10 to the negative 6th power meters per meter per degree Kelvin. I think better in SAE where the equivalent is 9.6 times 10 to the negative sixth inches per inch per degree farenheit. If I assume the exhaust is about 300 degrees F and the exhaust system is around 140 inches long I get about your amount of movement. My assumptions are rough and undoubtedly not exactly correct but the goal in this sort of a calculation is to see if you can get in the ballpark with something that is potentially reasonable. I would say this passes that test. In other words, 11mm could just be thermal expansion of the exhaust system.

To allow for that expansion the exhaust hangs on rubber hangers that have a lot of flexibility. If we take away that flexibility, we will bind somewhere else.

If the hitch is in the way and removing a little metal solves that, it is what I would do.

This makes sense. I wish there was an easier way but the grinder really made short work of it and I haven't had a single rattle or noise since even when climbing a steep incline. I suppose one could use the issue to justify buying an aftermarket exhaust though

[UR25IO]

Hi there i was just wondering with the bikes the curt two bar, does the hitch / bike rack bounces around agressively?

I had mine installed and yesterday went out with a bike rack attach to the hitch.. it is bouncing and wobbleing around like crazy.

Originally Posted by mabrahams

Bumper removed:


Right side where bumper slides out. You can see where there are a couple places where the bumper 'snaps' in. In the wheel well, you have three bolts that need to be removed, and once those are removed you have one under the felt panels that secures directly to the bumper. So total of four bolts, three exterior facing and one underneath. Make sure you get all four out before you start to pull. As noted on page 1, you also have bolts mounted on the bumper below, remove all of them.



I had to remove the 9mm exhaust bolt and also the rubber exhaust holder, in order to have enough clearance. Curt hitch is a pretty tight fit.
Photos of the hitch installed, and clearance between the hitch and exhaust.


Note the room between the hitch and exhaust. This is the same place where others were having issues with it rubbing.


Hitch installed, torqued down to 65 ft/lbs.


As you can see, the hitch is installed OVER the bumper support bolts, per instructions. There is no rubbing between the hitch and exhaust.

Tips: Be careful when pulling the bumper back. I read the directions to pull the bumper forward (ie: towards the front of the car) when it should have be read pull towards the rear of the car, to slide out. Installation was quick.

I removed the rear tail-lights and the felt covers; just so I had a bit more room to work with. I'm sure having both just a bit loose would be fine as well. Instead of cutting the small plastic piece that mounts to the underside of the car and the bumper, I just removed it. I was worried that there would be some flex in the middle of the bumper, but it's a pretty solid unit once everything is snapped into place.



EDIT: Here are two photos of the hitch being used:

[FactorX81]

mine bounces and wobbles a lot as well. I don't know what type of rack you have but in my case it is the rack doing the wobbling the hitch is solid. I have a thule 2 bike rack with the center folding arm similar to the rack in the above pictures.

[horsepower_and_hounds]

Originally Posted by FactorX81

mine bounces and wobbles a lot as well. I don't know what type of rack you have but in my case it is the rack doing the wobbling the hitch is solid. I have a thule 2 bike rack with the center folding arm similar to the rack in the above pictures.

As he said....the rack tube inside of the receiver is what is wobbling around. Mine with the Thule did the same thing so I put some 1in wide freight strapping in like shims. Now that I have the 1-Up rack it is gone. It has a expanding type interface that takes up the slop. Tight as a drum.....
I just have the hot exhaust contact which I have now strapped a thick rubber spacer in-between to let it ride on. Will see how that works

[AnShk]

Just installed the hitch from curt as it says in a manual.
I tested rattling without towing. Seems that after 10miles on a highway the hitch touches the exhaust but I do not know if it will make noise if I tow something.

Puzzled what to do next, do not want to have rattling while towing from west to east coast.

[JimD]

I don't have a hitch on my e88 yet but may do it. I currently tow with my Suzuki SUV. It has a class III hitch which has a 2 inch rectangular bar. It also has an eighth of inch or so clearance between the bar and the hitch. Depending on how the trailer is loaded it sometimes rattles. It only happens over bigger bumps unless the trailer is loaded improperly with too much weight in the back of the trailer.

With bikes on the back, I strongly suspect the rattling will be mostly the bikes and parts of the bike rack, not the bar fitup to the hitch. The weight of the bikes is going to take the slop out of the bar fitup and unless a bump causes enough acceleration up and down to overcome that weight, the bar won't move in the hitch. The way the bikes are held is unlikely to be as loaded (it could damage the bikes if it was) so I think that is where your rattling will come from. At highway speeds, I doubt you will hear a thing. Highways tend to be smoother than at least some secondary roads too. That may help.

I wouldn't worry about it. With a quality bike rack you should be fine.

[AnShk]

Originally Posted by scottn2retro

119190:
http://www.etrailer.com/pc-ELEE~119190.htm

119146:
http://www.etrailer.com/pc-ELEE~119146.htm


Looks like 119190 is rated to handle a trailer with even more lights than the 119146.

What wires did you tap into?

Just ordered Modulite kit for 135i here http://www.etrailer.com/Custom-Fit-V...id=20101170141

which fits BMW.

Someone can post how to DIY?!

[FactorX81]

Originally Posted by AnShk

Just installed the hitch from curt as it says in a manual.
I tested rattling without towing. Seems that after 10miles on a highway the hitch touches the exhaust but I do not know if it will make noise if I tow something.

Puzzled what to do next, do not want to have rattling while towing from west to east coast.

You need to grind down the muffler mount. Run your hand along the cross bar of the hitch where the exhaust hanger is and you will feel the paint worn away. When the exhaust gets hot it makes contact with the cross bar.

[NorthernDancer]

Looking at john08135 post in 2009 where he was launching 2 SeaDoos made me remember a story told to me from a friend who winters in Fort Lauderdale. People sometimes launch at low tide, boat ramp is extremely slippery and sometimes tow vehicle slips into water. No traction. Obviously I would not launch at low tide. Our cars are RWD and usually have high performance summer tires. I think I would carry some sand in an empty windshield washer bottle, just in case I needed it.

[AnShk]

I just installed modulite http://www.etrailer.com/Custom-Fit-V...id=20101170141

and it works!

You will need to ask manual which color is which on a modulite. The guys from etrailer send me a link for manual. Otherwise there was no description in the box.

[Max L]

I purchased 11184 hitch that I am planning to install on my 2011 128i. I am planning to get Thule rack to haul two bikes (990XT - http://www.thule.com/en-us/us/produc...90xt-_-5776509).

I am reading installation instructions and it says that non trailer loads (i.e. bike rack) must be supported by stabilizing straps. It does not seem like anyone is using any straps... Anybody knows what is the deal with these straps?

Also, as far as muffler rattle goes- can anyone confirm that 128i needs hitch/muffler hanger trimmed? I would rather do it all at the same time, during the installation, as my E82 is non sport package and I need to remove the whole bumper to install/work on the hitch...

Thank you,
Max

[AnShk]

Originally Posted by mxl556

I purchased 11184 hitch that I am planning to install on my 2011 128i. I am planning to get Thule rack to haul two bikes (990XT - http://www.thule.com/en-us/us/produc...90xt-_-5776509).

I am reading installation instructions and it says that non trailer loads (i.e. bike rack) must be supported by stabilizing straps. It does not seem like anyone is using any straps... Anybody knows what is the deal with these straps?

Also, as far as muffler rattle goes- can anyone confirm that 128i needs hitch/muffler hanger trimmed? I would rather do it all at the same time, during the installation, as my E82 is non sport package and I need to remove the whole bumper to install/work on the hitch...

Thank you,
Max

Max, I have 135i and I have about half inch distance when cold and not trimmed. The temp and all sorts of things should be same as for 128i, so I would recommend to trim, because mine rattle at some engine RPMs even without a load.