Replacing belts on 993
 

I will be replacing belts on my 96 this weekend and have a question. I have all tools and new belts but am unclear whether I need to also purchase new shims or do I use existing ones in there. I went over DIY but I am unclear whether or not I need to buy new ones or not. I want to be prepared before doing this.

Thanks, galileo

You do if the ones you already have are not enough to provide the proper tension. Plus, you do not need "new" ones to replace the ones you have; you need extra shims in case the ones you already have are not enough.

More shims = decrease belt tension.
Less shims = increase belt tension.

Are new belts different sizes?

there should be enough shims in place, the ones that aren't used to actually shim the pulley(s) are stored under the nut on the outside.

If it is an old-style pulley with the dished washer, but my new-style pulley didn't have any shims under the nut.

I just put new belts, among other things, on my 964. When I took them off, the alternator and fan belts had 3 shims inside and 1 outside on each pulley. Upon reinstallation, I tried to compensate for the new belts by using 4 shims on each pulley and still felt they had too much tension. I sourced a couple of additional shims for each pulley in order to lower the belt tension. They feel better (thumb test), but I should get my Krikit v-belt tension gauge in the next couple of days and then i'll be able to be more objective about the tension measurement.