C3 Seat to Floor Bolts... Grade 5?

[Mark E.]

In 1970, what grade bolt is used to attach the seat to the floor (4 bolts per seat)?

The replacement bolts I purchased are grade 5 (3 radial lines on the head). Given how important these bolts are for safety, I was wondering if they should be grade 8.

The bolts I removed don't match, so they're not a good reference.

Thank you!

[Gene M.]

Re: C3 Seat to Floor Bolts... Grade 5?

The indented head black phosphate finish grade 5 (3 radial lines on the head) are correct.

[Mark E.]

Re: C3 Seat to Floor Bolts... Grade 5?

Thanks Gene. Grade 8 is probably overkill when it's just bolted to fiberglass.

[Leif A.]

Re: C3 Seat to Floor Bolts... Grade 5?

Thanks Gene. Grade 8 is probably overkill when it's just bolted to fiberglass.

Mark,
Just to clarify...the seat track bolts pass thru the fiberglass floor pan and are threaded thru nut plates attached to the fiberglass flooring. They are NOT bolted to the fiberglass.

[Mark E.]

Re: C3 Seat to Floor Bolts... Grade 5?

I understand Leif.

My point is that the weak link in the attachment of the seat to the car is the fiberglass floor (via a small reinforcement plate). I suspect when force is applied (like during an accident), the fiberglass floor will fail first, not the bolt (or plate).