Originally Posted by
rumrunn6
I don't think those plastic covers affect the spring operation
I think it does. At least on the bikes I have worked on, there is a cavity where the spring sits, and one end is inserted in the cheesy plastic housing where it has a stop for the end of the spring. The other end fits in a hole in the canti braze on.
I prefer to use this as an opportunity to move up to one of the better Shimano caliper models. The plastic housing tends to be found on the bottom end/low end stuff. I also have salvaged these housings from various donor MTBs.