Turns out that my new radial mount calipers have exactly the same distance between mounting bolts as the holes in the upright - this means that the two pairs of bolts want to collide, exactly.

So I think what I need to do is make a thicker than usual bracket and position the calipers further out-board of the upright, so the caliper bolts then go past the ends of the bolts coming out of the upright. (I can't just offset the caliper as the upright lugs will get in the way).

The caliper bolts will end up about 25 mm away from the uprights, so the bracket will be a good 35 mm thick (increasing twisting force on the bracket bolts). Too much or am I worrying about nothing?

Photo or sketch would help.

Hub is yellow, upright is grey, caliper is red, bracket is green. Problem is that I am worried the bracket is too wide in the left-right direction on the diagram, due to the need for the bolts to miss each other.

Surely the caliper position is dictated by the disc. Are the mounting holes in the upright threaded or are the threads in the bracket?
Your brackets are on the same side of the upright as the disc ie the outside. This seems strange. The bracket is usually on the inside. What upright are you using? See pic below of some I made earlier.

Yes, I'm getting hats made up and need to decide the disc offset. So this distance is flexible until I make a decision on the hats.

The bracket does need to be on the outside of the upright unless I go for a hat with a *huge* offset (and of course I'd still need to clear the bolts on the other side so that would not help anyway).

Uprights are originally from a BMW. Your arrangement looks very neat but that won't work for me unfortunately.

I've done the calcs and apparently I can torque the bracket-upright bolts to about 65 ft-lbs which suggests they will be very securely anchored to the upright, this gives me some confidence that it will work.

I see the problem of the 2 bolts clashing, but couldn't you make the bracket a little longer in the up/down direction, and move the caliper up/around the wheel by say 15mm (enough to allow the holes to be far enough apart)?

So instead of moving left / right and having clearance/alignment issues, just move up/down or 'around the clockface' about the centre of the disc.

Might work......

Adam, rotating the caliper around was my first thought but it doesn't work. The calipers will hit the lugs on the upright unless they're lined up "straight".

I suspect the solution will be to make the bracket out of 6mm thick angle steel instead of 25x35mm aluminium bar. I think that will be easily strong enough, probably not much weight penalty either as it'll be less material.

Hmm, quick chat with a mech engineer suggests helicoiling the ally to improve the strength of the bolt from the upright, since I can't get a nut on that one. This seems sensible. He also suggests that the ally bar might be better than steel angle. So it looks like that is the plan.

Worth a try! Sounds like you have it sorted
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