Seat belt anchorages

[Short]

This is the guide for use on minibuses and coaches - ive gone for 7/16

D. Where seat belts, other than looped belts, are anchored to the seat frame or the vehicle floor they must be secured with mounting bolts in accordance with the following:

Minimum Acceptable Size and Grade of Bolts for Seat Belt Anchorage’s


Type of Anchorage


Single Anchorage


M8 High Tensile Steel, M10 Standard Material


Double Anchorage

7/16" Standard Material, M10 High Tensile Steel


Note: Bolt head marks

Standard Material = P, 4.6 or SAE equivalent

High Tensile Steel = S, 8.8 or SAE equivalent

No Markings = Standard Material

If the examiner cannot determine the grade of bolt it must be assumed to be of Standard Grade.

From memory, nuts are not stamped with a grade anyway. M12 is well above the recommendation, and they really have no way of checking the strength of the nut anyway. As long as the bolt head is stamped, I wouldn't worry!