While servicing the calipers, some shims just fell on the floor. Rapid review of the manual convinced me to put them back... 1) on one caliper I only have a single shim in the lower bold but not on the upper bolt. Is this normal? 2) installation is a pain! As a last resort I just used some CA glue and activator in order to stick the shims on the calipers during assembly Questions: 0) how to check for the caliper centering? 1) is there any better way to insert the shims?(glue is crude) 2) As they are quite thin (0.2mm +0.1mm so 0.3mm total), are we supposed to adjust them with rotor wear? 3) I was considering skiming an additional 0.3mm on the rotor and get rid of the shims. Does that make sense?
The shims are used to center the disc in the caliper for any manufacturing differences. I would not want to use a shim on top and none on the bottom, unless you can clearly measure misalignment of the disc in the caliper. Check your offset with NO shims and see it is equal top and bottom. Then see if a new set of pads fit in between rotor and piston. If they fit, you can do without the shims. The "tight" pad might wear a bit faster at first, but you don't want it dragging. If you need the shims, a dab of high temperature grease should allow the assembly. Ken
Definitely don't do that! Rotors wear fast enough Those are rather "thin" shims -- your SPC shows shims are available from 0.2 mm to 1.0 mm thickness. The centering of the rotor in the caliper doesn't have to be perfect, but I'd agree strongly with Ken that not using the same shim thickness at the top and the bottom would be very unusual, and you'd really need to be sure that that was the "right" thing to do before doing it (i.e., more likely that it was previously mis-assembled by someone else rather than needing different thickness shims)
Your assumption makes sense : the other caliper needed some service while this one was properly packed with grease and good dust boots. So was probably serviced earlier (hence the missing shim). At the end of the day, this missing shim will require to remove the caliper, waste almost a bottle of break-fluid, and new unused pads for the measurement!
