Seat belt mounting

[sballard]

I am in the process of mounting new seat belts in my car. I've taken the side panels off and removed the plastic bolts that were in the holes in the picture. I measured the plastic bolts with a micrometer and came away with a measure of 10 mm diameter and 1.25 pitch. Yet, when I screwed in the bolt, it was a loose fit. I could wiggle it in the hole. The thread pitch is OK. I had the same problem with the hole in the other side. What size should these bolts be?

[ChrisBennet]

They are SAE thread 7/16-20, not metric. I have no idea why.

[sballard]

Wow. I never would have guessed. Maybe Porsche had to comply with some US safety dictate when imported in 1972.

[HarryD]

Originally Posted by ChrisBennet

They are SAE thread 7/16-20, not metric. I have no idea why.

This size is standardized worldwide. All seatbelt hardware uses this thread. The shoulder and head may be different for your application.

Use SAE Grade 5 bolts. Higher grades can be too brittle.

[dicklague]

I went through the same thing years ago with the bolt on the "B" pillar. I was making a fitting so that the pillar could be attached to the roll bar, and help stiffing the structure. I could not figure out the metric thread.

I went to a Hot Rod parts store, and the counter guy said....."you sure it is not SAE?"

He said many metric cars had SAE seat belt attachments.....he was right!