Hello fellow VFR'ers. I just purchased a very clean, '03 VFR w/ ABS. It has a scant 6200 miles on it and the only mods so far are a Penske shock and F4i fork internals. My phantom knock appears once the bike warms up a touch, while I'm travelling (doesn't matter if I'm accelerating, decelerating, clutch in or out), and is a consistent knocking that changes tempo as the bike speeds or slows. I don't feel it and can only hear it when the wind noise doesn't overpower it (30 mph and below). Once I drop below 18 mph or apply the brakes it quiets. On the center stand, in neutral, there is no knock, regardless of clutch in or out. I've tensioned the chain, cleaned and lubed it and just did a fresh oil and filter change but my knocking persists. Tires are free of rocks/debris and my rotors and sprocket look great. Does the ABS system make any knocking noise? Surely it isn't the valves because I'd still hear it in neutral, right? Does this sound familiar to anyone?
phantom knock diagnostics please
Started by allgrainbrewer, Apr 24 2012 04:58 PM
5 replies to this topic
#1
allgrainbrewer
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- Why VFRD?:To learn and troubleshoot VFR related queries and modifications.
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Posted 24 April 2012 - 04:58 PM
#2
JeffLaurence
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Posted 24 April 2012 - 05:05 PM
Could it be related to the front floating rotors?
#3
kaldek
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Posted 24 April 2012 - 05:24 PM
Any chance you could ride the bike past a mate at 25 miles an hour and have them listen to it to see where the sound is coming from? Pull the clutch in while you do it or kill the motor so it's easier to pinpoint.
BMW K1300R is my new girlfriend.
#4
allgrainbrewer
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Posted 28 April 2012 - 03:24 PM
Could it be related to the front floating rotors?
Turns out this hard to diagnose knock was related to the floating rotors. I realized I had really bad drag on the front wheel and upon inspection noticed that my left rotor was not true. I managed to pry it back into a better state of true and, low and behold, my knock is gone! Hooray! Happy day my VFR purrs as it should.
#5
JeffLaurence
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Factory Team Rider
- Why VFRD?:Gain info about the bike, troubleshooting problems
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Posted 28 April 2012 - 03:26 PM
Curious-- was there no pulsing at the lever?
#6
allgrainbrewer
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- In My Garage::2003 Honda VFR800A
Posted 29 April 2012 - 07:29 PM
Curious-- was there no pulsing at the lever?
I never did feel it anywhere in the bike. One of the "ah hah!" moments that clicked within my brain and helped me realize my brakes may be the culprit was that the brakes seemed a bit "grabby" when I did apply them. Rolling along there was no twitch in the lever but once I put the squeeze on, there was a notable sticky spot, now it's obvious, where the rotor was rubbing. I'm beyond ecstatic that the knock is gone and that my sleuthing was rewarded with a no cost solution. I'm getting a bit of front brake squeal now but I think it's safe to assume that the pads are unevenly worn and I'll address a more thorough brake inspection at the next major over overhaul interval, which is 1600 miles away, or right around the corner. I'm obsessed with my new bike!
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