Finally sorted out squealing breaks.

[Morgan1]

06 GS300. Front breaks had been squealing for a while, had them checked when MOT was done, cleaned and copper greased. Still squealed. Next changed pads, still squealed. This time replaced discs, old ones where still good but had a small lip on them. No more squealing. Surprised that a very small lip on the discs caused sutch horrendous squealing. 

[Verbout]

I'd have ground the lip down, if the discs were within tolerance.

[Morgan1]

10 minutes ago, Verbout said:

I'd have ground the lip down, if the discs were within tolerance.

Garage did suggest grinding the lip down but l went for replacement as was not a lot of differents in cost.

[Verbout]

31 minutes ago, Morgan1 said:

Garage did suggest grinding the lip down but l went for replacement as was not a lot of differents in cost.

Yep, there wouldn't be if you're paying someone.

 

[NemesisUK]

Surely the lip is where the pads don't contact the disc? I don't see how the lip would cause squeal. All discs form a lip as they wear.

A contaminated disc could and changing them just removed the contaminant?

[Britprius]

Removing the lip changes the frequency that the disc rings at. This alone can cure brake squeal. When cars had drum brakes on all four wheels it was not unusual on a drum that squealed to stretch a spring round the drum hooking it on to it'self. This changed the frequency of the drum ringing out of the human hearing range.

John