For my son's science experiment, we tested Coke, Vinegar, 50/50 water and phosphoric acid, and lemon juice. We used some rusty bolts off my truck and repeated the experiment 3 times. The 50/50 phosphoric acid removed rust the best, but incredibly lemon juice was very close behind and was better than Coke or vinegar. I couldn't see using the lemon juice on larger pieces (too expensive and too much squeezing), but it was interesting.
Don't know if Phosphoric acid would cause problems with chrome, but you can get a gallon for $15 at Home Depot.
Good luck.
