Brake Pad Shims

[Mogan]

What role do the shims play?

I changed the front tire today and did the front brake pads while everything was torn apart. I noticed that I had shims on one side and not the other (not my first pad replacement--the last one was at Sunnyside). Is it okay to run without shims? I've apparently done so for many thousands of miles!

 

[HaulinAshe]

The "I'm not an engineer" response is yes, it is okay to run without the shims. However, you may cause premature wear on the caliper pistons because of the rougher surface of the pad backing (metal). You may experience unusual brake squeal caused by vibrations of the pad backing against the caliper pistion. And lastly, you MUST be careful not to run the pad down to the minimum pad thickness as this may allow the caliper piston to travel beyond it's design spec and actually dislodge, although this is not too likely.

I would order some shims and then take the time to polish the end of the caliper pistons, very carefully, with some 600. Then put the shims in where they belong and ride.

IMHO

Oh yeah, forgot to mention heat transfer from the pad to the piston and subsequently fluid is greatly increased without the presence of the shims. The layered effect of the pad and shim helps resist heat transfer. But I'm no engineer!

 

[Mogan]

The "I'm not an engineer" response is yes, it is okay to run without the shims. However, you may cause premature wear on the caliper pistons because of the rougher surface of the pad backing (metal). You may experience unusual brake squeal caused by vibrations of the pad backing against the caliper pistion. And lastly, you MUST be careful not to run the pad down to the minimum pad thickness as this may allow the caliper piston to travel beyond it's design spec and actually dislodge, although this is not too likely.
I would order some shims and then take the time to polish the end of the caliper pistons, very carefully, with some 600. Then put the shims in where they belong and ride.

IMHO

Oh yeah, forgot to mention heat transfer from the pad to the piston and subsequently fluid is greatly increased without the presence of the shims. The layered effect of the pad and shim helps resist heat transfer. But I'm no engineer!

Makes sense. Thanks Jeff!!

Just looked up the parts numbers. Front shims are not sold separately but as a set with pads. Arrrggh.