Brake pulsation, or; how I learned to love burning cash at the dealership - Kawasaki Versys Forum
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post #1 of 24 (permalink) Old 06-12-2019, 01:39 PM Thread Starter
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Brake pulsation, or; how I learned to love burning cash at the dealership

Just got home from the Kawasaki dealer... They spent about an hour trying to figure out why my brakes pulsate and came up with questions but few real answers. Also, they charged me $50 for their time since they couldn't figure out how to charge it to Kawasaki.

What they did do: set tire pressure, road test, check rotor runout, visual inspection, etc.

What they found: rotor runout at or below .003, wheel has a nick in it but appears to be properly round, no visible signs of neglect. Brakes pulsate slightly (according to their definition, I guess), especially at low speed. Tire pressures were slightly low.

What they blamed: low tire pressure may be causing the front tire to cup and pulsation while braking.

Huh?!? I don't know what their definition of cupping, but they said it was significant (it's only just starting to show some cupping, and all Road 5 fronts do), and I've NEVER heard of cupping causing a brake pulsation and ONLY a brake pulsation.

Here's what I found after a brief look around the internets: big bikes and big guys with a sense of their own mortality seem to like to hold the front brakes at a stop. This causes crud from the pads to get embedded into the rotor, resulting in a variable coefficient of friction across the swept area of the rotor.

Dressing the rotor surface is supposed to be an effective cure for this, at least until the fat operator bakes more crud into the rotor.

I burned $50 to learn all this. I hope this saves someone here from the same experience.

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post #2 of 24 (permalink) Old 06-12-2019, 08:57 PM
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Dressing the rotor surface is supposed to be an effective cure for this, at least until the fat operator bakes more crud into the rotor.

De-burring the dish will eliminate pulsation. Anyway, nice post to say you burned $50..
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post #3 of 24 (permalink) Old 06-12-2019, 09:00 PM Thread Starter
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Deburring the dish? I'm not sure what that means. Please elaborate?

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post #4 of 24 (permalink) Old 06-12-2019, 09:20 PM
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The dish, as we know has got venting holes - a perforated dish. during its service period the dish develop burring around the edge of the vent holes on the dish. This causes slight pulsation and can be removed by skimming the dish. I have gone through this and have machined the dish.

Hope my explanation meet your understanding as we are miles apart.
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post #5 of 24 (permalink) Old 06-12-2019, 09:22 PM Thread Starter
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No, that makes sense. Will I be able to feel raised edges on the holes with my fingernail or is it smaller?

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post #6 of 24 (permalink) Old 06-12-2019, 09:36 PM
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You should be able to feel the sharpness around the edges of the holes.

Though the roughness maybe be small by measurement , but its end result it high due to the brake pressure and speed of rotation of the dish.
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post #7 of 24 (permalink) Old 06-12-2019, 09:47 PM Thread Starter
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Cool. I'll check it in the morning. Thanks.

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post #8 of 24 (permalink) Old 06-12-2019, 09:57 PM
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https://www.r1concepts.com/blog/how-...-slotted-only/

some reading materiel for your understanding.
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post #9 of 24 (permalink) Old 06-12-2019, 10:09 PM Thread Starter
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Just because I'm not sure I'm quite the idiot you have me feeling like with these posts, I went out and checked for burrs.

There's only 14k on the bike as of my trip home, and those rotors are glass smooth. I can, however, actually feel a difference in the slippery nature of that smoothness. Like a varying glaze on the surface.

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post #10 of 24 (permalink) Old 06-12-2019, 10:21 PM
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Quote:
Originally Posted by 52Degrees View Post
Just because I'm not sure I'm quite the idiot you have me feeling like with these posts, I went out and checked for burrs.

There's only 14k on the bike as of my trip home, and those rotors are glass smooth. I can, however, actually feel a difference in the slippery nature of that smoothness. Like a varying glaze on the surface.
No worries bro , we are just sharing knowledge and at no point will i underestimate another person, just because of a simple question. It take intelligence to ask questions.

anyway what you feel on the disc is quite normal for a perforated disk unless you have deep grove marks. If the pulsation or rumble from the braking is not causing any braking issues , ride on, sometime it will self cure by itself , like on long rides.
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post #11 of 24 (permalink) Old 06-12-2019, 11:04 PM Thread Starter
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Yeah... When I really think about it, this feels almost exactly like some of the trucks at work. Drivers get the brakes really hot, then back into a dock and set the park brake. Pretty similar to my commute. I come into a long off-ramp from about 80 mph, brake hard and take the right third of the left lane. The off-ramp is uphill, so I'm holding position with a brake, but I'm on the right side of the lane, so my right foot is down. So I hold the front brake. Since I'm not one to do anything mildly, I of course have a pitbull death-grip on the brake lever.

Anyway, I'll post back here and let everyone know how this progresses. If I'm wrong, I'll own it. But, at this time, I'm close to 100% sure of my diagnosis.
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post #12 of 24 (permalink) Old 06-13-2019, 12:02 AM
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Totally understand bro...we are not far a part ,as we are in the same industry.
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post #13 of 24 (permalink) Old 06-13-2019, 10:23 AM Thread Starter
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Funny thing about crappy tools... They don't last forever. I killed my die grinder cleaning the glaze off this part of one rotor. The difference, though, is extremely clear.

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post #14 of 24 (permalink) Old 06-13-2019, 07:46 PM
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god job. Keep informed.
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post #15 of 24 (permalink) Old 06-13-2019, 08:09 PM Thread Starter
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I spent 2.5 hours on it and only got the outsides done. Had I used that time to drive to Harbor Freight for an angle grinder and a flapper disk, then just pulled the wheel off and removed the rotors, I'd be done and my hips wouldn't hurt from siting cross legged on the concrete.

Lesson learned. Lol. I'll get back on it Wednesday.
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post #16 of 24 (permalink) Old 06-14-2019, 07:20 AM
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Brake shudder at slow speed is usually an indicator that the bobbins allowing the rotor to "float" are seized. Can be fixed with a nut, bolt and drill.

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post #17 of 24 (permalink) Old 06-14-2019, 07:42 AM Thread Starter
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Not in this case. Runout was checked at the dealership and is within spec. This is a clear case of crud naked into the rotor surface.

In the process of removing said crud yesterday, I noted each rotor had an area of heavier buildup.

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post #18 of 24 (permalink) Old 06-19-2019, 10:13 AM
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I usually jack up the wheel, then rotate the wheel while using some some 220 grit sandpaper on the brake pad mating area of each rotor - then take a pencil and some brake cleaner and spray and rotate the bobbins on the floating rotors. Sometimes, I pull the brake pads and run them back and forth on sandpaper laid on a good flat surface - just enough to break any glaze.

This is a common problem on some Italian motorcycles. I suspect the brake pads. Maybe.

Both my 650 Versys had this issue but this 1000 Versys .... not yet.

No matter where you go - there you are.
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post #19 of 24 (permalink) Old 06-19-2019, 10:29 AM Thread Starter
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This stuff is really tough. I don't know if I drove through a really bad patch of crap or what, but it's seriously stuck and don't come off without rotational abrasives. Even then, it's still not easy.

I'm considering pads as well.
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post #20 of 24 (permalink) Old 06-20-2019, 05:56 AM
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Quote:
Originally Posted by 52Degrees View Post

I'm considering pads as well.
After you solve the dirty disc (sounds porno), I recommend EBC HH brake pads. They work miles better than the stock and don't glaze my EBC discs. The discs were replaced by the DPO, he claimed the OEM warped.
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