I would not use brake cleaner. Motor cleaner might be ok, but I wouldn't use that either. Brake cleaner seems to be a common multipurpose cleaner in RC for some silly reason. It is a caustic liquid and will cause pitting of the surface of metals, especially plated metals.

The best thing to use if you need it is either straight isopropyl alcohol in as high a percentage as you can get(ideally no lower than %90), or a cleaner specifically for the purpose such as Caig Deoxit or other electrical contact cleaner.