I just thought I would post my experience with the front disc squealing on my CB400F. The squeal has been particularly bad since I bought the bike. Very bad. In fact, it was so bad that I was unconsciously modifying my riding behaviour to compensate!
My first steps in tackling the problem was to go through a comprehensive list of recommendations that can be found elsewhere on the forum. New pads, ensuring the caliper was free to move and properly set up, bleeding the brake, de-glazing the disc with sandpaper and so on. I noticed a slight improvement when I de-glazed the disc. But it was only a slight improvement and the effects didn’t last for long.
It got me thinking though. What if the glazed disc was behaving in a similar way to running a wet finger over a wine glass. The “slippy / grippy” nature of the pads against the glazed disc were causing the disc to squeal.
I removed the disc from the bike and could see as well as being glazed is was also very pitted. You can’t really see the pitting from a distance but on closer inspection it was very apparent. To be fair, it is 45 years old.
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No amount of sandpaper or elbow grease was going to sort it out. I thought of perhaps getting the brake skimmed in some way but after some consideration I decided to buy a new ABE disc which was sourced from David Silver. It was a fair amount of money, but (a) we probably spend more on making our bikes shiny and (b) it’s the front disc! A pretty important component when considering the important line between riding and death ;-)
I installed the new disc and it has cured the squeal problem completely! No squeal whatsoever. Nothing.
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Of course, I am not suggesting that anyone with this problem should go out and buy a new disc. However, if you find yourself in a situation where you have set up all of the braking system correctly and still have the squeal problem – de-glazing in some way may work for you also.
I should also add I am now regularly cleaning the new disc with isopropyl alcohol (IPA) to stop the nasty stuff building up again…
Dave
