It makes noise if you have a starter that needs the shims. You can install the starter with or without shims to "start" with. You can take out or put in the shims without taking the starter out.

Assume shim(s) are installed
Loosen bolt furthest from you
take out bolt closest to you (tab end of shim)
pull out shim(s)

If you look at pic you can see that the shim has one hole and one slotted hole on the end. If you leave the bolt on the slotted end in, you can pull the shims out. The other bolt is holding the starter in place.