James-man

There is a big threaded hole on the rear of my '86 just above the license plate. It looks like about the size of the stock tow hook but impossible to get to without removing bumper.

What is its purpose?

Many years ago, I used to think it was for a venting tube but when I finally look at it from underneath yesterday I found that nothing attached there and it was a large threaded hole.

Cadillac art

It’s the tow hook hole. Tow hook screws in no problem.

James-man

Mine doesn't. Not enough clearance below the plastic rear to get the tow hook to the hole perpendicular to the ground. Can only reach the hole at an upward angle which prevents any true threading. Wonder if this is funkiness for 86' and older cars or just me???

Thanks!

linderpat

Something's going on back there with your car. Post a picture.

Mrmerlin

The tow hook screws straight into the rear bumper if it is pointing in any other direction,
then the mounting socket has been damaged

James-man

Got it screwed in. Just had to pull upward against the plastic to get it started and ultimately a tight fit there, but fine.

Thanks!

FYI - I am looking into making a custom mountain bike rack that rests upon the top of the rear bumperettes. The screwed-in tow hook gives a nice solid bit to secure a rail. This is looking doable. Just looking at an option that MIGHT be simpler than taking off a wheel and putting the bike in the hatch and would definitely be cleaner than putting a muddy, post-ride bike in the hatch.

jetson8859

If your going to use the tow hook socket as a mounting point, I would take your tow hook to any decent machine shop and have them make you a threaded insert out of a good quality steel. The tow hook is cast metal and doesn't have a lot of give, it will snap before it bends and you don't want to lose a bike or have it banging into the car due to a broke mounting point.

James-man

Great idea.

Thanks!

jpitman2

FWIW the thread is uncommon - Knuckle 20mm in your case - early cars were 15mm. See https://www.gewinde-normen.de/en/knu...d-din-405.html for details. As above the tow hooks wont tolerate sideloads and are a poor choice of materials for that job. Also , have you checked your front tow thread for useability? Many have an alloy plug corroded in place. See other threads on the fix.
jp 83 Euro S AT 57k

Bigfoot928

BTW I’d never let a wrecker driver use the tow hook on the front or the rear. Years ago a wrecker used the rear tow hook and pulled the tow hook to cinch down the 928 when I wasn’t looking. They ended up paying for rear bumper shocks, and rear bumper cover repair....