Tow Hook Thread size

[fatboycowen]

A few years ago, the tow truck driver at the track needed to pull my car up onto a flatbed after i had a ball joint break. The bastard only threaded the hook in a turn or two, and when the car was half way up the ramp, it ripped out.

Ever since, the tow hook won't thread in. It appears that just the first thread or two are damaged, and the remaining are good.

Does anyone know the thread size, so i can get a tap and clean up the threads? So far, i have been lucky not to need a front tow hook, and my luck may run out....

I'm planning on installing fold down tow hooks permanently once its fixed. Anyone have recommendations?

Thanks,

[JNS BMW]

An odd size for BMW as it is not metric. I think it's ACME 5/8-8 RH and that came from a reliable source. Hope it helps.

[fatboycowen]

Wow, that does help! I'll take some measurements of my tow hook and see if i can verify that.

[NeilM]

I just checked and it's definitely not Acme thread, which uses a trapezoidal form with a flat apex and valley. The tow hook has quite rounded threads. I read someplace that it's a deliberately non-standard size to prevent people from using inappropriate bolts.

According to Ron Stygar it's M16x3.

That's quite close to 5/8"-8, which translates to M15.875 x 3.175mm. Probably close enough that you wouldn't know the difference for very short thread engagements—once you're up to 9 threads you're half a thread pitch off though.

However M16x3 isn't a normal size (std = M16 x 2), but then again neither is 5/8-8 (std = 5/8-11). Even McMaster-Carr doesn't carry either of those sizes of tap, so the point may be moot.

You could try taking a sacrificial tow hook, tapering the end slightly with a grinder or file, cutting longitudinal flutes in it with a Dremel, and using it as an improvised clean-up tap. Might work.

Neil

[fatboycowen]

I did some more research earlier, and came up with M16x3 as well.

[tammer]

Instead of tapping the threads, just do this:
http://www.elephantmotorsports.com/b...rap-p-564.html

-tammer

[JNS BMW]

This is some good information, guys. Glad to know it's M16x3 which is indeed an odd size.
The best measurement we got was the ACME 5/8-8 and it's interesting how close that is to the M16x3. Thanks again NeilM

[TeamDFL]

Take a close look at another tow hook. The thread form is rounded, like Edison light bulb threads.

Tow straps are pure win.

[ScotcH]

Take a close look at another tow hook. The thread form is rounded, like Edison light bulb threads.

Tow straps are pure win.

Can someone show me how to mount those? E46 front and rear. Does it just go around the bumper shock? I have one, but didn;t mount it since the tow hook it just so easy

[mpassioned]

Tow straps are pure win.

Hi,

My E30M3 aftermarket bumper, covers too much of the stock tow loop rendering it useless should it ever be needed. Where can I buy 1 or 2 of these? This is exactly the solution I have been looking for.

Thanks

[NeilM]

Hi,

My E30M3 aftermarket bumper, covers too much of the stock tow loop rendering it useless should it ever be needed. Where can I buy 1 or 2 of these? This is exactly the solution I have been looking for.

Thanks

See the link to Elephant in Tammer's post above.

Neil

[fatboycowen]

Thanks for all the advice. I ended up ordering the motorsports tow strap from Turner, as they are local.

In my research, some websites say to thread it between the bumper cover and the outer grill sheet metal. Other websites (bimmerworld) say you need to cut a slot in the bumper cover, so that it won't crack the cover. What did everyone here do with E36 M3s.

Thanks again.

[tammer]

Thanks for all the advice. I ended up ordering the motorsports tow strap from Turner, as they are local.

In my research, some websites say to thread it between the bumper cover and the outer grill sheet metal. Other websites (bimmerworld) say you need to cut a slot in the bumper cover, so that it won't crack the cover. What did everyone here do with E36 M3s.

Thanks again.

On my E36 I have it coming out above the bumper, as on the red car in the photo at the EMS site. There is some chance that it could crack the bumper cover if used. I plan to cut a slot in the bumper and cover eventually; I just haven't gotten to it and it will certainly function safely as-is (and stock 325i bumper covers with 3 layers of different-colored paint on them aren't exactly precious!).

For installation, you want to loop the strap around the bumper shock mount and back through itself before feeding it forward through the bumper, so that pulling on it causes it to self-tighten.

-tammer

[jjvincent]

After reading this, I was wondering if it just makes sense to just buy a used bumper shock. I would asume that most of the e36's take the same shock across the board. With that I looked up the part number for a RF bumper shock and found that it fits everything from a 318 to a M3 (51118176272). Then the RR shock pretty much goes along the same lines (51121977550). Then I went online and found a used one for $25. I bet with some more research you could find one for $15.

I would think that with the vast quantities of e36's out there, you could fine a used one even on this site.

[fatboycowen]

Ohhh, i didn't realize that the threaded hole for the tow hook is within the bumper shock. Every time i have had the bumper off, i haven't paid much attention to that. This is a great solution. I'll try to pull it apart and verify.

THANKS!

[lowside67]

Does anybody use a tow strap to regularly winch their car into the trailer? I dont really want to use the stock tow hook as I'd like to have something I leave attached and the anodized aluminum folding ones seem a bit flimsy for regular use...

Mark

[mpassioned]

See the link to Elephant in Tammer's post above.

Neil

Hi,

The 2 straps mentioned in this thread differ. Elephant's strap has a loop only on 1 end, and I want a loop on both ends. I haven't talked to Jack, but maybe there are different styles ava that he has?

[tammer]

Hi,

The 2 straps mentioned in this thread differ. Elephant's strap has a loop only on 1 end, and I want a loop on both ends. I haven't talked to Jack, but maybe there are different styles ava that he has?

It's pretty much all loop. Once wrapped, the part that sticks out is still a loop to pull on. Here is a photo when I had the rear bumper off to install it (and do some other work back there); I had hung the strap on the bumper shock containing the tow hook so I wouldn't forget to install it.


When wrapped, for the rear bumper it pokes right out through the tow hook cover:


-tammer

[mpassioned]

Thanks Tammer, I appreciate the pics, and description. I think I can make that work for me.

[racerrick]

OK, if you happen to get this... or for all other readers... the "bastard" in this case was, unfortunately, YOU as you are supposed to always install your tow hook BEFORE you go on track. Not doing so not only increases the chance of a VERY HARD WORKING AND LIKELY UNDER OR UNPAID TRACK WORKER FROM HURTING YOUR BABY; but, also increases the likelihood that you'll negatively impact OTHER DRIVER'S TRACK TIME! So... going forward INSTALL YOUR OWN HOOK BEFORE GOING ON TRACK!

[pbonsalb]

The kids these days are prepared — they run their hook or strap 24/7.

[aeronaut]

the kids these days are prepared — they run their hook or strap 24/7.

lol!

[modifiede30]

Bringing this thread back - looking to know how you route this strap thru the normal tow hook cover from the bumper support the way its pictured. This would seem to risk ripping the bumper once the strap is under load. The strap is either laying over the top of the bumper support, or under it, and when under load, it'll want to straighten out and put a lot of pressure on the top or bottom of that tow hook hole. Did you drill a hole in the bumper cover support to route the strap in a straight line from the bumper shock, or is it just laying over / under the aluminum support under the bumper cover? Or maybe an alternative is to put a very short eyebolt into the tow hook in the bumper and run the strap thru it (hard to find the bolt size that'll fit though).

Assuming you've not damaged the bumper in the off road incident that necessitated the tow, the above seems like a recipe for a damaged bumper.