Isopropyl alcohol or specialist disc brake cleaner.?

Question

I've searched forums, and some people say one is better, others say the other is better. What has happened is, I used some wd40 as there were tiny rust spots on my disc brakes, but now my brakes squeal, so I am looking to completely clean the disc and pads.

Answer 1

With heavy (relatively speaking) oil on your rotors like that, I'd use a chemical brake cleaner from the car parts store instead of alcohol.   Alcohol actually works pretty well but it's best for just removing surface grime and airborne oil contaminants like car exhaust, etc.   If you use alcohol, be sure to buy the 91% version (not the normal 70%, and definitely not rubbing alcohol (which has oil in it)).   If it's not by the other alcohols in the drugstore, look for it near the diabetic supplies.  

Another great cleaner for rotors and pads is plain old Ajax powder.  Make a slurry paste with it and scrub the parts with it using your fingers or a nylon brush.  It cleans better than a lot of petro chemicals do, and if you want to combine it with some 400g sandpaper you can really get things clean.  

I do the alcohol and Ajax thing, personally.  Occasionally I'll break out the brake cleaner for the cassette, but it's mostly for the auto now.   :o)

Answer 2

The best thing a cyclist can do with WD40 is to put it on a very high shelf in the garage; then get some specialist disc brake cleaner for your rotors. If you have hydraulic brakes, be careful not to get any on the seals.

For other bike maintenance, get some PTFE maintenance spray and some lithium grease. If you put WD40 on the chain it will just loosen any grease left on it, and rinse off in the next rain/wash, leaving your chain to turn to scrap metal in a matter of weeks.

Answer 3

  Use regular disc brake cleaner as alcohol leaves a residue on the metal and the brake cleaner is formulated to clean without any residue hanging on.

  This is not an application for WD40.

Answer 4

Break cleaner from Auto Zone will work fine.  Be very careful it is highly flammable.