Series 3 E-type seat retaining bolt and seat belt retaining bolt sizes/specs

G’day, I’ve removed the seats and seatbelt from my S3 etype whilst reupholstering and of course they have gone walk about.

Can anyone tell me where I can find the size/specs for these bolts so I can pop down to my local bolt supplier for them, I am not looking for the badged bolts for concourse cars, just the correct spec of size/thread.

They’re not “badged” bolts, so authenticity will prevail. They are a Pan Head, Phillips and from memory, but I will check today and come back, are 5/16 UNF x 1 1/4 long.



Isn’t it interesting how such parts just “walk off”!!! Ha Ha
Here’s a photo of the front seat OEM rail screw(s) and hardware…

Bill is spot on with the size AND they are POZIDRIV, not Phillips! Since most production was destined for North America all the hardware is SAE (Imperial), not metric. Also note under the outside (sill side) seat rail(s) is an “L” shaped bracket.
Do you still have the pair?
Finally - under the rear rail mounting points, the nut is welded to the bracket and there is a round 1/4" thick spaces under the rail.

If you’re not that concerned with “authenticity” then this might work for you:

Hex key bolt

Good luck with your interior refurbishment!

Happy Trails,


The fasteners on E types were not SAE to suit the American market. They were British Standard (BS) because the UK had not yet converted to metric. BS Fine and BS Coarse diameters and thread pitch coincides with SAE.

Edit: did some quick research: (British Fasteners)

An interesting, quick read.

Only the coarse thread, where each are 18 TPI. The 5/16 BSF is 22 TPI, while the SAE UNF is 24 TPI.

Your research article refers to BSF and UNF corresponding, or being equivalent, but that doesn’t mean that their thread pitch is the same, only that they could be used for corresponding duties.

Thank you everyone, great info, I am back on track, cheers.