Now that I had clearance for the spacer washers to sit, I had to figure out which thickness of spacers I needed to center the calipers. Others had posted using a fender washer on each bolt.
Yeah. That didn't work for me.
From Amazon, I purchased 3/8" ID x 1 1/2" OD stainless steel fender washers, that were listed as being 0.040" thick, as well as same size but 0.060" thick. This way I had some leeway for spacing. I was still under the impression I would only need one spacer per bolt. I drilled out a group of both thickness washers to 9/16" ID so the M14 caliper bolts would pass through.
Got a caliper mounted with a 0.060" spacer between the caliper and the spindle. Lightly torqued the bolts. And noticed immediately that the rotor was NOT centered in the caliper.
OK, take it back a part and rethink.
I measured each spacer washer with my calipers, and marked its size in Sharpie. So I knew what selection I had to work with.
I quickly realized I could not use my calipers to measure the gap between the rotor surfaces and the caliper pistons. Measuring point was too deep. Scratched my head for a bit. Until I remembered a little set of tools I bought years ago on a whim, and had never used. Snap gauges! Though finicky to use, they were perfect for measuring this gap.
Through several cycles of mounting, measuring gaps, demounting, repeating for each caliper, I ended up walking gaps into this:
Driver's upper outboard: 0.79"
Driver's upper inboard: 0.81"
This was using 0.063" and 0.061" thick spacers between the caliper and spindle.
Driver's lower outboard: 0.80"
Driver's lower inboard: 0.82"
This was using 0.065" and 0.061" thick spacers between the caliper and spindle.
Passenger's upper outboard: 0.80"
Passenger's upper inboard: 0.82"
This was using 0.063" and 0.055" thick spacers between the caliper and spindle.
Passenger's lower outboard: 0.80"
Passenger's lower inboard: 0.82"
This was using 0.063" and 0.055" thick spacers between the caliper and spindle.
I called 0.002" difference between outboard and inboard good and the rotor centered in the caliper.
Honestly, this is academic. I am using digital micrometers and snap gauges, and I don't do this for a living. There is most definitely some tolerance/error in my measurements. I was trying to get it as close as I could with what I had.
However...two things:
1) the brake pistons will 'self center' the pads on the rotor. A little misalignment will be OK
2) the numbers look good
Stainless steel fender washers used as spacers, shorthand marked with measured thickness. 58 = 0.058"
My digital micrometers are decent quality, and I am not a complete hamfist using them, but they are not lab grade. Good enough for what I am trying to do.
The cutest little set of snap gauges. They were definitely the right tool for measuring the gap between the brake rotor surface and the caliper pistons.
Top of driver's side caliper. Photo doesn't really show it, but the rotor looks centered in the caliper.
Bottom of driver's side caliper. Photo doesn't really show it, but the rotor looks centered in the caliper.