The bolt that clamps the column to the steering box spline - anyone know what size bolt this should be? M8 seems a little small. And should it be high tensile grade? Thanks.
Original Post
Replies sorted oldest to newest
@SteveMarson posted:The bolt that clamps the column to the steering box spline - anyone know what size bolt this should be? M8 seems a little small. And should it be high tensile grade? Thanks.
If we're talking about the clamps on either side of the rubber donut coupler for the steering column, then yes, it should be an M8, regular grade. The shafts coming from the steering box and the steering column are fine-splined but also have a flat on one side to allow the M8 bolt to pass through the clamp. If you tried an M10 in there, it won't go all the way through. There originally was a lock tab under the nuts to prevent them from backing out. If you don't have those, you can use an M8 Nylok stop nut to prevent them from loosening (try at ACE Hardware).
I looked for a tightening torque but didn't find anything in my Bentley or Haynes service manuals other than "Tighten Securely". An M8 used in a clamp usually calls for 11-15 ft. lbs. if you have a torque wrench. I would expect an upper limit of 20 ft. lbs. for a bolt in a clamp.
Gordon - thanks. I’ll investigate further. Should the column have a spline in its inner part, to match the steering box? I think it’s smooth but need to have another look.
Steve, it should be fine splines(60 I think) as is the coupler that slides onto it. In addition, there is a D shape to the shaft that the clamp bolt will touch.
And yes, M8 x 1.25. You could use a 5/16"- 24 fine thread grade 8 since the size is almost identical to the M8. Just remember to use a 1/2" wrench instead of a 13mm.
I drill the head of the bolt(or you can buy them that way) for a safety wire.