Installing a tow hitch on my E92 M3

[nsogiba]

I will preface this post by saying that installing a hitch on an M3 is not for everyone and will probably ruffle a bunch of feathers. That being said, I don’t really care since there are plenty of similar cars all over the world towing a lot more with far inferior brakes, power, and tires/suspension. The track guys tow small trailers loaded up with a spare wheel set, tools, fuel, you name it.

Anyhow - I am a firm believer in using fun cars to their full extent, so every fun car I buy usually gets a trailer hitch in order to haul my bike rack and tow a small trailer for track days, Home Depot runs, whatever. My Corvette towed great, with the towing package I installed (more power, stronger brakes, oil cooler, LOL).

Not only does it prevent me from having to use my wife's Rav4, but I love the looks I get and pissing off purists: "You're not supposed to tow with that car!!!!!!"

LOL, hold my beer. These cars are more than adequate for small loads.











Really I want to just get my bike back on there so I can start riding again, with the gyms still being closed.





The plan is to install a hidden hitch setup that has a vertical receiver behind the bumper cover. When I want to use the hitch I will install a 90 degree adapter, like this concept.



The problem is that nobody makes a hitch like this for the M3, so I bought a generic E9X hitch knowing it would have to be modified, and immediately proceeded to cut it up to clear the exhaust tips and bumper mounts.



So after a few nights of cutting and tacking, here’s where I’m at right now – one vertical receiver hitch for an E92 M3.







I should have everything mocked up later this week and drop it off at my welder’s for final welding as my little 110V MIG isn’t up to the task of burning in the thick steel.

[nsogiba]

Here is the system fully mocked up and just tacked together. It needs final welding and a coat of paint.

[roastbeef]

Awesome! I dig it.

[DRLane]

I want one!

[ThunderMoose]

I ran a hitch on my E46 for my tire trailer. very convenient!

[kayha12]

I need this! Been running a roof rack with 2 wheels on it - driving to and from the track haha

[nsogiba]

Originally Posted by kayha12

I need this! Been running a roof rack with 2 wheels on it - driving to and from the track haha

That's not a bad option either, but it has to be a hassle throwing 2 wheels up there and then tying them down...any pics of the setup?

[roastbeef]

so the main modification was to step it out towards the rear of the car to clear the center exhaust hanger? it may have been possible to just incorporate hangers into the hitch design and get rid of the oem hanger.

[roastbeef]

Originally Posted by nsogiba

That's not a bad option either, but it has to be a hassle throwing 2 wheels up there and then tying them down...any pics of the setup?

i run a rack that carries two wheels. it would be an easy job for you, given your skill level, and it adds zero weight when it is off the car. i used oem bases and had an aluminum basket fabbed and secured to the bases when the bases were on the car. it was done this way so there is no adjustment to be done- the whole assembly lifts on and off the car. its a one minute, one man job. well under the weight limit, and you forget its there. i simply didn't have room for a trailer and didn't want to deal with lights and registration on the trailer.

[kayha12]

OEM BMW roof bars
Random roof basket from eBay
1 ratcheting strap per wheel

Super easy to take on and off, the oem roof is already tapped for the bars. I keep the basket mounted to the bars, so it's just a matter of 4 screws to mount/dismount everything then throwing the wheels on and securing them

[DRLane]

Originally Posted by kayha12

OEM BMW roof bars
Random roof basket from eBay
1 ratcheting strap per wheel

Super easy to take on and off, the oem roof is already tapped for the bars. I keep the basket mounted to the bars, so it's just a matter of 4 screws to mount/dismount everything then throwing the wheels on and securing them

Any reason not to have all 4 wheels up top? Weight? The fact that vertical orientation could create rolling projectiles?

[kayha12]

Originally Posted by DRLane

Any reason not to have all 4 wheels up top? Weight? The fact that vertical orientation could create rolling projectiles?

Yeah, weight primarily. I believe per OEM manual the weight should not exceed 150 lbs or so and yes that's a lot of projectiles that could come flying off haha this setup can handle 90 mph high way speeds no issues, very little additional wind noise too

[roastbeef]

Correct. It's a weight issue. There are four m6 bolts keeping it up there. The bases have feet that support the weight, but the sheer strength of four m6 bolts is what's keeping it up there.

[DRLane]

Originally Posted by roastbeef

Correct. It's a weight issue. There are four m6 bolts keeping it up there. The bases have feet that support the weight, but the sheer strength of four m6 bolts is what's keeping it up there.

Great insights guys! For the time being I'll keep wiggling three wheels in to the back seat area. Just a pain to get in / out. Thinking of removing the rear deck.

[kayha12]

Originally Posted by DRLane

Great insights guys! For the time being I'll keep wiggling three wheels in to the back seat area. Just a pain to get in / out. Thinking of removing the rear deck.

Yeah prior to the roll bar install that's what I did too, backseat down, 1 in the trunk and 3 in the backseat area. Now I'm rocking 2 on the roof rack, 1 in the trunk, 1 as passenger haha

[DRLane]

Originally Posted by kayha12

Yeah prior to the roll bar install that's what I did too, backseat down, 1 in the trunk and 3 in the backseat area. Now I'm rocking 2 on the roof rack, 1 in the trunk, 1 as passenger haha

I'm running BK harness bar and fixed buckets, stripped rear seats. So the only entry in is through that trunk slit. Once I update to a proper half cage (JP marketing version) should be much easier. Or I love the trailer idea to bring gas cans, Etc. Great inspiration from y'all though 🙏🏼

[dogbone]

I'm more disturbed that you take your cars out in the rain.....what's that about?

[dparm]

Yeah no way can the roof handle four tires with wheels mounted. A 275/35R18 Hoosier is about 23 pounds, and an 18x10 forged wheel is probably 21. Cast wheels would be a few pounds heavier. Plus, the rack itself has weight.

[nsogiba]

Originally Posted by roastbeef

so the main modification was to step it out towards the rear of the car to clear the center exhaust hanger? it may have been possible to just incorporate hangers into the hitch design and get rid of the oem hanger.

Cutting up the hangers and muffler hanger rods would have been much easier than what I did, but I did not want to make any modifications to the car, permanent or otherwise. At this point the car can be returned to "stock" at any time by just removing the hitch.

I also had to redrill the mounting holes to move up the hitch in order to avoid hitting the exhaust tips, and trim off the tops of the mounting plates. Finally, the side plates were trimmed at the bottom, again to provide clearance from the tips.

Other than than, it bolted right up

Originally Posted by roastbeef

i run a rack that carries two wheels. it would be an easy job for you, given your skill level, and it adds zero weight when it is off the car. i used oem bases and had an aluminum basket fabbed and secured to the bases when the bases were on the car. it was done this way so there is no adjustment to be done- the whole assembly lifts on and off the car. its a one minute, one man job. well under the weight limit, and you forget its there. i simply didn't have room for a trailer and didn't want to deal with lights and registration on the trailer.

The roof rack is a nice design too, but pretty limited in terms of total weight as well as having to strap everything down very well to prevent it going flying. When I used to track my Vette, my normal "loadout" included 4 wheels/tires, heavy toolbox, jack, 5 gallon jerry can, extra oil, etc. It's nice not having to put all that up on the roof, or stink up the interior of the car with gas, oil, tires and tools.

The hitch does add some additional weight (maybe 40#?) but for me the additional practicality from having so much more cargo capacity makes it worth it. Besides, my M3 will only see occasional, non-competitive track duty, so the weight penalty is pretty negligible.

Now, I need to find a set of "extension" harnesses for the tail lights so that I can splice into those instead of hacking up the stock light pigtails.

[Richbot]

legend

nice work

I have done the roof rack wheels and the tire trailer wheel transport (in a Civic). Roof rack knocked Civic's performance right in the dirt, mileage was bad, everything was bad. Tire trailer, carrying much more, barely made a dent in highway mileage, and was just all 'round better. Unloading consisted of unhooking the trailer. It was awesome.

Big fan of class I hitches on regular cars. Wish it was standard equipment.

None of the trailer people have a plug and play (or wire tap and play) BMW light and signal harness?

[roastbeef]

Originally Posted by nsogiba

Cutting up the hangers and muffler hanger rods would have been much easier than what I did, but I did not want to make any modifications to the car, permanent or otherwise. At this point the car can be returned to "stock" at any time by just removing the hitch.

I also had to redrill the mounting holes to move up the hitch in order to avoid hitting the exhaust tips, and trim off the tops of the mounting plates. Finally, the side plates were trimmed at the bottom, again to provide clearance from the tips.

Other than than, it bolted right up



The roof rack is a nice design too, but pretty limited in terms of total weight as well as having to strap everything down very well to prevent it going flying. When I used to track my Vette, my normal "loadout" included 4 wheels/tires, heavy toolbox, jack, 5 gallon jerry can, extra oil, etc. It's nice not having to put all that up on the roof, or stink up the interior of the car with gas, oil, tires and tools.

The hitch does add some additional weight (maybe 40#?) but for me the additional practicality from having so much more cargo capacity makes it worth it. Besides, my M3 will only see occasional, non-competitive track duty, so the weight penalty is pretty negligible.

Now, I need to find a set of "extension" harnesses for the tail lights so that I can splice into those instead of hacking up the stock light pigtails.

i get it, 100%. a trailer would be more useful. i entertained the thought, but i didn't have the room for one, and the hitch presented another hurdle.

the biggest bummer i've had with the rack was after a track day at laguna seca. my track wheels were covered in brake dust from a full day and two of them were on the rack. it rained pretty good at night and all of the brake dust from the two wheels on the roof was washed out of the wheels and baptized the car.

[nsogiba]

Originally Posted by roastbeef

i get it, 100%. a trailer would be more useful. i entertained the thought, but i didn't have the room for one, and the hitch presented another hurdle.

the biggest bummer i've had with the rack was after a track day at laguna seca. my track wheels were covered in brake dust from a full day and two of them were on the rack. it rained pretty good at night and all of the brake dust from the two wheels on the roof was washed out of the wheels and baptized the car.

Because racecar! Sucks man.

Keep in mind that some of the HF trailers are designed to fold up when not in use.