Posts: 449
Threads: 6
Likes Received: 0 in 0 posts
Likes Given: 0
Joined: Apr 2013
Before I get a chance to tear the front brake apart, was wondering if anyone had any ideas:
Noticed yesterday coming home the front brake pulsates at speeds > 50mph under moderate to heavy braking. Bike has only 6k miles on it. I was thinking that one of the rotors might be slightly warped, but I don't see how. I plan on taking a look at both rotors and pads when I get a chance this weekend.
Posts: 23,403
Threads: 697
Likes Received: 482 in 220 posts
Likes Given: 597
Joined: Apr 2025
Are you sure its the brakes? How is the front tire?
Posts: 915
Threads: 66
Likes Received: 0 in 0 posts
Likes Given: 0
Joined: May 2014
I had a bad set of rotors. Waranteed. They are kind of thin and get hot easily, especially in the mountains. I use both brakes a lot now rather than mostly the front to try to keep them cooler.
Posts: 274
Threads: 6
Likes Received: 0 in 0 posts
Likes Given: 0
Joined: Aug 2013
(10-02-2015, 09:32 AM)Motogeezer1949_imp Wrote: I had a bad set of rotors. Waranteed. They are kind of thin and get hot easily, especially in the mountains. I use both brakes a lot now rather than mostly the front to try to keep them cooler.
^this. That sounds like warped brake rotors
Posts: 2,757
Threads: 26
Likes Received: 0 in 0 posts
Likes Given: 0
Joined: Mar 2014
I had this pulsating problem (very rapid grab release, grab release) with the front brake on my Bonneville last year during braking. Braking from a high speed was machinegun like and very annoying.
I changed the rotor and it was gone.
Very strange for it to happen on a low mileage machine that has never been abused, but it did.
No such problem with the CB.
Posts: 994
Threads: 61
Likes Received: 43 in 16 posts
Likes Given: 8
Joined: Dec 2013
I've replaced two front brake rotors on my VFR800 over the past ten years that suddenly, and for no reason warped. My bike exhibited the same symptoms you describe. Out of curiosity, was your front tire replaced recently? The mechanic could have damaged the rotor when replacing the tire.
Posts: 2,757
Threads: 26
Likes Received: 0 in 0 posts
Likes Given: 0
Joined: Mar 2014
(10-04-2015, 05:09 AM)Dave_imp Wrote: I've replaced two front brake rotors on my VFR800 over the past ten years that suddenly, and for no reason warped. My bike exhibited the same symptoms you describe. Out of curiosity, was your front tire replaced recently? The mechanic could have damaged the rotor when replacing the tire.
No, the tire had not been changed.
While I was at it I took the opportunity to change the rotor with an EBC kit which included a new rotor and brake pads.
It much improved the braking so in a way I'm glad it happened.
Posts: 78
Threads: 6
Likes Received: 0 in 0 posts
Likes Given: 0
Joined: Feb 2015
They sell a dial indicator / vise grip tool for measuring rotor run-out. Maybe a parts store that lends tools has one. YouTube will show you how to use it. A micrometer is needed for thickness variation.
Posts: 53
Threads: 0
Likes Received: 0 in 0 posts
Likes Given: 0
Joined: Apr 2015
Might just be brake pad deposits on the rotors.
Posts: 2,290
Threads: 75
Likes Received: 1 in 1 posts
Likes Given: 0
Joined: Aug 2013
(10-04-2015, 12:37 PM)immgunn_imp Wrote: They sell a dial indicator / vise grip tool for measuring rotor run-out. Maybe a parts store that lends tools has one. YouTube will show you how to use it. A micrometer is needed for thickness variation.
A runout check is good advice. A basic check, to see if there is any runout, can be done by clamping a wire, or other object, in touch with the rotor and then rotating the wheel. Any significant runout can be then observed by eye. To measure that runout you will need a dial indicator. A reasonable quality dial indicator is not expensive. Runout limits are described in the service manual. I don't have my manual by my side but will post the runout limit if you need.
Cheers.
Minimum rotor thickness is 3mm. I measured mine last week.
