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Hawkstone front brake anchor bolt

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  • Hawkstone front brake anchor bolt

    Hi, Is the Hawkstone front brake anchor bolt stepped? The anchor plate has a large slot in it for a 5/16" bolt and could probably move under braking.

  • #2
    Hi David,had a quick look at the anchor bolt on mine and that certainly appears to be the case. Although it might also be a straight bolt with a collar under the head. Further, the slot on the anchor plate is open ended on mine, presumably to allow for and easy detachment of the front wheel. Don't know if this was original or an after market mod prior to my ownership. Hopefully someone with greater knowledge and/or documentation can advise more accurately for you.


    • #3
      Click image for larger version

Name:	Tin Hub front brake plate anchor arm spacer.JPG
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ID:	82686Click image for larger version

Name:	BHC tin  rear hub & front brake plate.JPG
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ID:	82685 The tin brakeplate with the slotted anchor arm is located by the offside metalastik bush retaining bolt, which is 3 3/16" long x 3/8" BSF, with a sleeve 5/8" O.D. x 7/16" long which locates in the slot, David. I am a bit puzzled by your 5/16" reference.

      The later model tin hub brakeplate had a lug with a 5/16" hole in it. That was located by a bolt passing through holes in the fork loop, forward of the bushes. My 1963 20DC mk2 roadster is like that, but my 1959 Hawkstone and 1960 Scottish have the slotted type.

      The slots and the sleeves can wear, and I had the slots built up with weld and re-machined to take out the movement you mention, along with new sleeves; see attached photos. ( Ignore the rear hub in one of the pictures)

      Hope this helps

      Ian C


      • #4
        Thanks for replies Adrian & Ian. My backplate has the open-ended slot but I didn't know that there should be a sleeve. Will make one up. Ian, yes the bolt is 3/8"!


        • #5
          Hi David. The torque arm spacer, as it is called; part # M9/F12. Better than a stepped bolt because they wear, and a spacer is cheaper to replace than a stepped bolt. The standard clamp cup bolts are 2 3/4" x 3/8"BSF, 3 off. By adding the 7/16" long spacer to that one gives 3 3/16". You will want 2 flat washers and a nyloc nut. Bolt lengths exclude the hex head.

          Ian C.


          • #6
            Thanks Ian. Made up spacer/sleeve. Think I may need a run of weld on back-plate to take up slight movement . Bolt is good in meantime but may get slightly longer one in future-nylon not engaged.


            • #7
              Hi David. That's interesting. I have just measured one of my bolts and it is definitely 3 3/16" long excluding the bolt head. Maybe a nyloc 1/2 nut would do it? Unfortunately none of the parts books appear to list the bolts. Attached is a drawing showing the detail on a TCS; SAS will be the same.

              Do you have the clamping cups correctly positioned? The one on the inside to which the spacer fits is thinner than the other 3, identified by a flatter profile. You can see it Click image for larger version  Name:	TCS Fork Drawing-Pinned Bushes and Damper Position..jpg Views:	0 Size:	110.5 KB ID:	82698 on the drawing. If you have a standard one fitted, that would make the difference.

              Also, it is possible there may not be a washer under the spacer; see drawing

              Last edited by IanCordes; 10/07/2020, 08:04 AM.