mroberts

I'm looking to make a camera mount for my car, and I've noticed there is a very large screw / bolt in the middle of the C-pillar.

Has anyone removed this ? If so, would this be a good spot to attach a bracket for a camera mount bar ?

Is it a bolt or a screw ? I'm somewhat reluctant to start randomly undoing things on the car !

Thanks.

Sam Lin

Does it look like a slightly convex dome, black plastic? If so, that's just a threaded plug in a hole that was put there for 3-point rear seat belts. Many harness bars attach using those points, they're some of the strongest on the car.

Sam

Dave

Easy solution, install a harness bar at this location and install a camera mount ON the harness bar.

mroberts

It looks like a metal 1/2" diameter phillips head screw, but the phillips head is much smaller, maybe 1/8" to 1/4" across. Sounds like I can try unscrewing it without the roof falling off

Harness bar: $100
Harness: $200
Harness bar camera mount:$100

3/4" square aluminium and angle for bracket: $10

EDIT: Yup, little plastic plug. I'm assuming it's metric. Good to know I now have somewhere solid to bolt onto.

I'll post how the mount turns out.

mroberts

I'm trying to work out what size bolt goes into that hole. I've tried metric 10mm, but it's too small, and a 12mm is way too big.

In the service manual it's called the "shoulder bolt" and is used to attach the seatbelt mount when you fit rear shoulder belts. Does this mean it's some sort of funky size ? 7/16 doesn't fit either.

Dave in Chicago

It's 11mm x 1.25mm pitch (pretty darn fine). Typically has a 17mm hex head on it, grade 8 or 10.9. Torque spec is around 35 ft-lbs as I recall. DO NOT try to put the wrong bolt in there or you will be in a world of hurt (ask me how I know).

It's a VERY odd size to find. Chances are you could order it special or get a bolt from a Porsche dismantler. In varying lengths and shoulders, I'm pretty sure it's the same thread as all of the mounting bolts for seatbelts throughout the car. My also be common to VW and/or Mercedes.

Hope this helps. I agree the best solution is a harness bar and associated camera mount, but that's just my opinion.

Good luck,

mroberts

I'll bite .. how do you know ?

Thanks for the spec. I had my suspicions it was 11mm (based on the fact that 10 and 12 didn't fit) but no-one had 11mm bolts locally. There's a specialty fastener store nearby, so I'll give them a try.

Thanks

Dave in Chicago

Had tried the wrong size, messed up the thread a bit, then proceded to break off a nice super-hardened grade 8 bolt in there. Drilling it out included lots of smoke, toasted drill bits (in increments of 3/10 th's of a mm, mind you), and cursing. Not fun. I am now the proud owner of a very nice 11mm x 1.25 mm tap.

Yup, 2 minutes of "gee, this doesn't feel right" turned into about 4 hours of "can this bloody bolt actually be the hardest substance known to man?". My own dumb fault. Good news is it's all better now

Hans

As per Dave above, M11 x 1,25 is no standard size.
The bolts used in belts are grade 12.9, the toughest you can get.
I do not expect these to be available from the local speciality fastener store, but you wont know thill you asked.
If everything fails, you might want to start at the scrap yard, and pick up the bolts from a VW / BMW / Merc.
Driver & pass side lower bolts close to the floor are normally easiest accessible.
TakeCare

mroberts

Turns out a 7/16-20 fits great. Make sure it's a "fine" thread. I can thread it in with my bare hands - don't need to force it at all.

Dave in Chicago

That's what I thought too. See post above on drilling out bolt. Use other bolt at your own risk.

Good luck,