Bolts for middle seat - safety.

What kind of bolts do I need for the middle seat. I know they are M8 but do they need to be specially rated as they also bolt down through the middle seatbelt.

I've got some carbon steel (SAE1008), will they suffice?

Wanna make sure its spot on for the obvious safety reasons

Is this front or rear seats? In the front, the middle lap belt mountings should be on the floor next to those for the two outer seats.

It's the front middle seat. They're mounted on the floor like you say.

Anybody...?

payydg said:

Anybody...?

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According to the Driver & Vehicle Standards Agency, Individual Approval (IVA) Manual.........for seat belt mountings.
QUOTE.. Bolts used in structural areas should be of grade 8.8 or better. Such bolts will be marked 8.8 or 12.9 on the hexagonal head. UNQUOTE.
So if you fit 8.8 or 12.9 then you will be ok. There's likely to be more stress on the seat belt bolts in a collision than on the seats themselves.

Correct, but don't fit seats in defender that have intergral seatbelt buckles as the seat box isn't designed to take the loads

Nice one chaps! Great info. Thank you very much.

Where could I get a copy of that manual?

The seat belt mounts go on the seat box for the middle seat right?

payydg said:

The seat belt mounts go on the seat box for the middle seat right?

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On a 90, they're mounted to the rear tub, just in front of the bulkhead. The seat box itself is not used to secure the seatbelts and only holds the seats themselves.The mounting points for the middle lap belt should be immediately next to those for the outer two seat belts. On mine at least, the bolts are already in position so it would be a case of using these to fit a middle seat belt. Standard fitment is a manually-adjusted lap belt only on the middle seat, and this is acceptable for the MOT Test.

If you want a 3-point belt in the middle, you'd really need to fit a pillar to the top of the bulkhead to raise the shoulder strap above the top of the middle seat. Otherwise the forces will be in the wrong direction in a crash and would force the occupant downwards. You need a secure upper mounting so the shoulder belt holds the upper body back.
This image from Exmoor Trim is a good example of how not to do it:
http://www.exmoortrim.co.uk/images/stories/virtuemart/product/EXT001-9-ex1_web.jpg

Oh I see. Thanks for the heads up!

Typically i bought the exmoor trim floor mounted inertial reel belt and am now trying to work out how to mount it safely

Stick to using proper seat belt bolts, 7/16 UNF as they are the correct grade. These a clause somewhere that you can substitute 2 smaller bolts so long as the cross section is larger. i can't find that now but it mattered becuse I raised my shoulder centre seat braket off the bulhead by 2" and used 2 off 3/8" bolts. Search e-bay and there's loads.

rob1miles said:

Stick to using proper seat belt bolts, 7/16 UNF as they are the correct grade. These a clause somewhere that you can substitute 2 smaller bolts so long as the cross section is larger. i can't find that now but it mattered becuse I raised my shoulder centre seat braket off the bulhead by 2" and used 2 off 3/8" bolts. Search e-bay and there's loads.

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This +1, and to ensure the bolt/seat belt eye is mounted through to sold metal mounting plates, not the bodywork. When modifying seat belts/installing harnesses I use the largest plates I can fit to the receiving area and, if possible, run one long plate between mounting points to spread load points.