Tow hitch mounting questions

[Coyote_ar]

Hi everyone, so i want to build and install a tow hitch on my car.

Im planning on replicating this
8616

With the square tubing for hitch instead of the J shaped one.

The doubt i got, is the 4 holes where you bolt the bar to the chasis.
8617

I see that my car has those, but i dont see any threads on them. What kind of hardware do you use to bolt them? do you need to put some kind of nutsert or something like that there?

Your help is appreciated.

[shogun]

check here if there is a retrofit instruction under E34 https://bmweba.com/

[632 Regal]

I think the frame part is boxed in, look to see if there is any access to insert a nut and some way to hold it when tightening the bolt.

[Coyote_ar]

Thx for the info Shogun. Based on what those instructions say, those holes should have threads on them. i will clean them and see if i can find any.

Regal, yeah i mean i can put a nutsert in there, its like a rivet nut. that makes it easier since u dont need access to the other side.

BTW i have a 4hp22 trans, would this be a problem towing a light trailer? say 750kg max?

[shogun]

4HP22 is no problem to tow a light trailer, it is used in many cars with much more HP https://en.wikipedia.org/wiki/ZF_4HP22_transmission
But I would recommend to install an external ATF cooler. Heat and age are mainly what causes transmission fluid to degrade, and this only leads to more overheating. The ideal range for fluid temperature is between 175 and 225 degrees, and every 20 degree drop in fluid temperature can help to double the life of your transmission. heat chart http://www.txchange.com/heatchrt.htm
https://mechanics.stackexchange.com/questions/24167/normal-operating-temp-for-an-automatic-transmission

[632 Regal]

Put the aux cooler before the radiator not after so it doesn't over cool the fluid.

[genphreak]

Mine had threads, IIRC. But it has been years, will have to take a look and let you know. I had to source fasteners though, am pretty sure they were M8 or M10 and I remember buying high tensile ones. I doubt they were necessary. Once added, the rear-end drops about 6mm (and the front rises). I added a 10mm Delrin 'donut' shaped spacer to the rear spring perch, but a stiffer spring works fine also.

[Coyote_ar]

Put the aux cooler before the radiator not after so it doesn't over cool the fluid. I recently bought a 100% aluminium radiator, that doesnt have the heat exchanger. A while ago, a friend's 540i had a leak on the heat exchanger, and ruined his trans. I never liked that heat exchanger there, so i was planning on getting a big oil cooler and a thermostat. But so far i havent decided which one to get, and more importantly where to put it. I like those mounted parallel to the ground, with a fan to assist when slow on traffic. I guess doing all that stuff before hauling a trailer would be a nice idea.

This is the radiator i got, i never liked those plastic tanks on the OEM radiator. Seen to many fail on where you connect the hoses (mine is already half broken there).
8619


Mine had threads, IIRC. But it has been years, will have to take a look and let you know. I had to source fasteners though, am pretty sure they were M8 or M10 and I remember buying high tensile ones. I doubt they were necessary. Once added, the rear-end drops about 6mm (and the front rises). I added a 10mm Delrin spacer) to the spring perch, but a stiffer spring is fine too.

Nice, i will check with those bolts once i clean the threads. My rear springs are already quite a bit taller and stiffer than regular suspension, since i installed a CNG tank in the back (plus i wanted a nice stance and a sportier ride).

This is the current stance, the rear springs are QUITE stiff, even with 2 people in the back, the suspension hardly drops.
8618
PS: please ignore my broken rear bumper :p
i bumped it on a uneven street corner and it broke in half doh