Front brake pulsing ... cured itself eventually.

utopia · 27-12-2015, 09:39 AM

I've had the oft reported pulsing from my front discs for 5yrs or so, with mot advisories each year.
Its been unnoticeable at speed but rears its head when trundling along in slow moving traffic etc.
I've checked them for truth and even thickness, cleaned the bobbins and gently scoured the surfaces, all with very little effect.
However, the pulsing has been diminishing gradually over the years (as confirmed by the mot tester too).
This kinda ties in with the thinking that this pulsing is often caused not by warped discs but instead by some kind of unevenness in the surface characteristics of the disc.
This is often described as uneven "tempering" of the discs, for which the cure is subjecting them to repeated cycles of heavy braking to get them really hot, followed by allowing them to cool and repeating as necessary.
I've never actually done this, but I did notice a slight improvement after similar incidental treatment during the 2011 Mallory trackday.
Since then I've made a point of occasionally given them the heavy braking routine whenever it tied in with my general riding, but nothing more specific than that.
However, the improvement has continued and has now reached the point where it is virtually unnoticeable and I can once again trickle up to traffic lights on the front brake alone, without pogo-sticking as the brakes pulsed.
It seems that my persistence has saved me the cost of a new pair of discs.

One theory that seems to hold water ('scuse the pun about to be made) is that parking the bike up with wet pads is a bad idea, as they cause localised corrosion of the discs, which will clearly affect their smoothness of operation to some extent.
In fact I've recently heard of a case where this has caused serious, visible pitting in pad-shaped areas on the discs when the bike has been parked up for over a year.

In my case, another possible cause is that my bike had two former owners (both ladies, though I make no gender-based comment here) and neither of them did more than a few hundred miles on the bike.
It could therefore be the case that the discs were never properly used "in anger" in their early life and hence they were never properly tempered.

Either way, it seems possible (likely, even) that the so called "warped disc" syndrome is a misnomer, and that surface defects are the more likely cause.

27-12-2015, 09:39 AM	#1
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,546	Front brake pulsing ... cured itself eventually. I've had the oft reported pulsing from my front discs for 5yrs or so, with mot advisories each year. Its been unnoticeable at speed but rears its head when trundling along in slow moving traffic etc. I've checked them for truth and even thickness, cleaned the bobbins and gently scoured the surfaces, all with very little effect. However, the pulsing has been diminishing gradually over the years (as confirmed by the mot tester too). This kinda ties in with the thinking that this pulsing is often caused not by warped discs but instead by some kind of unevenness in the surface characteristics of the disc. This is often described as uneven "tempering" of the discs, for which the cure is subjecting them to repeated cycles of heavy braking to get them really hot, followed by allowing them to cool and repeating as necessary. I've never actually done this, but I did notice a slight improvement after similar incidental treatment during the 2011 Mallory trackday. Since then I've made a point of occasionally given them the heavy braking routine whenever it tied in with my general riding, but nothing more specific than that. However, the improvement has continued and has now reached the point where it is virtually unnoticeable and I can once again trickle up to traffic lights on the front brake alone, without pogo-sticking as the brakes pulsed. It seems that my persistence has saved me the cost of a new pair of discs. One theory that seems to hold water ('scuse the pun about to be made) is that parking the bike up with wet pads is a bad idea, as they cause localised corrosion of the discs, which will clearly affect their smoothness of operation to some extent. In fact I've recently heard of a case where this has caused serious, visible pitting in pad-shaped areas on the discs when the bike has been parked up for over a year. In my case, another possible cause is that my bike had two former owners (both ladies, though I make no gender-based comment here) and neither of them did more than a few hundred miles on the bike. It could therefore be the case that the discs were never properly used "in anger" in their early life and hence they were never properly tempered. Either way, it seems possible (likely, even) that the so called "warped disc" syndrome is a misnomer, and that surface defects are the more likely cause.