Walt, Brake cleaner is actually the worst product for plastic. As far as I know, no current car manufacturer uses plastic parts on their drums or disks, which is what the cleaner is for. If you are cleaning your brakes, and get spray on the shoes or pads, you have to discard them because of the dectructive residue left by the cleaner.
The reason I asked is because it's well known that you can use carb cleaner on brakes, but not vice versa. Brake cleaner is too harsh on carbs with plastic parts (float bowls ect.) while carb cleaner isn't strong enough to affect them. Not to mention, carb cleaner can usually be had for $2-$3 a can while most brake cleaners run about the same as Gun Scrubber.
All the products mentioned, Gunscrubber, Brake Cleaner, Carb cleaner are bad on plastic, brake cleaner being the worst. I accidentally got gunscrubber on a video game joystick, and it melted it like it had caught on fire. I would never use any of the products mentioned on a plastic part.
If carb cleaner "cleans" as effectively as Gunscrubber, and doesn't erode the finish, I would consider using this product. I always wipe the parts down with Brakefree and or WD-40 afterwords, so I am not concerned about residue.
Too bad none of my Hollys are blued, then I wouldn't have to ask
.