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Imperial brake caliper bolt and shim(?)


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Driving home from picking up my new to me Classic VX I lost a front brake caliper bolt.

The second bolt was still there but quite loose already. So my 120 miles trip home was cut short after about 10 miles and ended on a recovery vehicle. 

After some research I found it's a 7/16 x 1-1/4 UNF bolt plus washer. In my case the washer on the bolt that I didn't loose seems to be an M12. I will replace that with a 7/16 once I get them.

To my surprise there was a very thin washer between the caliper and upright, also about 7/16 (or 11mm) ID and about 1'' (or about 25mm) OD by 0.8mm (1/32?)

I checked a build manual of the 1990s and couldn't find anything about that washer or shim.

Trying to find that shim seems to be impossible, at least for me. I couldn't find a 11mm ID and about 25mm OD washer at all. What do people use in that place if anything at all? Maybe I'm just looking in the wrong place?


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It's just a shim washer most good engineering / nut & bolt suppliers will carry them, 

You can add or subtract to centralise the caliper over the disc, and square them up to as some of the machining on the uprights leaves a lot to be desired.

The OE Triumph calipers are not that sensitive to being perfectly central as there is sufficient piston travel to accomadate this.

The HiSpec are more sensitive to this as you can end up with a pad dragging as it cant retract enough.

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