This picture shows a typical cast caliper/pad mounting bracket with a factory installed wrap over pad mounting shim. This design works well but the issue arises when rust, corrosion and the accompanying scale forms between the wrap over shim and the bracket. Even if the coating on the shim holds up and doesn’t allow the shim to rust the bracket will still rust. This becomes a major issue in any area where road salt (including ocean salt water) residue is present.
This vehicle had two winters of driving on it. The scale build up moved the shim upward and prevented normal pad (application and release) movement.
Replacing the shim is the ideal way to service this condition but if the part is only available as part of an expensive hardware package some may choose to clean the scale, lubricate and reuse the part.
Even if new you should lubricate the area that contacts the bracket. Use a sliding brake lubricant and apply without going to extremes.
Also lubricate the caliper mounting/pad contact bracket with the same lubricant. In this case, you are using the “brake grease” for corrosion prevention not lubrication.
You should have to gently tap the shim into position. If it fits on by just pushing it with your fingers, it doesn’t have the correct amount of indexing or holding pressure on the end taps.
When you start brake work and see a system looking like this (note the heavy flaking corrosion on the parts), you can figure you are in for a service experience on a severely rusted brake system. Even if during the original brake reline service everything was lubricated correctly after a few years, the lubricant is gone and rust and corrosion starts.
We will have more of the story brake lubrication next week for Tech Tricks Tuesday.
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