Front floating brake rotor "clunking tolerances"?
Thread Starter
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Tourer
Joined: Jan 2010
Posts: 304
Likes: 1
From: Woodburn, OR. USA
Front floating brake rotor "clunking tolerances"?
I have googled the snot out of this issue, and have found everything from, "it's normal" all the way to, "dude get that changed out ASAFP!"
Is it normal for the front floating rotor to have a bit of "radial play" from the "isolating rivets" and hub? With the bike suspended on my HF lift I noticed that the rotor slightly "clunks" when I apply the front brake and put "rotational pressure" back and forth by hand on the wheel. I could see where the rotor was gripped tight by the pads/caliper, and the "isolating rivets" and hub had a bit of "radial play" making the "clunking".
I have always noticed it for a short while when I first take the bike out for a ride "cold", but then don't notice it after everything is "warm". I suspect the rotor gets warmed up from friction against the pads and expands a bit taking up any slack in the assembly, hence the "loose tolerances". The front brake works great (knock on wood) there is no sign of excessive wear on the rotor and its not warped, etc. but then again I'm not a brake rotor expert. Is this within normal tolerances for a floating rotor? The service manual only addresses rotor thickness and lateral runout, but doesn't mention this situation as far as I can tell.
PS:
This could defnately be mistaken by some for the dreaded "front end clunk", but its not... I upgraded to the new heavy-duty washer and inspected/adjusted the column assembly, and its tuned nicely.
Thanks for any input!
Is it normal for the front floating rotor to have a bit of "radial play" from the "isolating rivets" and hub? With the bike suspended on my HF lift I noticed that the rotor slightly "clunks" when I apply the front brake and put "rotational pressure" back and forth by hand on the wheel. I could see where the rotor was gripped tight by the pads/caliper, and the "isolating rivets" and hub had a bit of "radial play" making the "clunking".
I have always noticed it for a short while when I first take the bike out for a ride "cold", but then don't notice it after everything is "warm". I suspect the rotor gets warmed up from friction against the pads and expands a bit taking up any slack in the assembly, hence the "loose tolerances". The front brake works great (knock on wood) there is no sign of excessive wear on the rotor and its not warped, etc. but then again I'm not a brake rotor expert. Is this within normal tolerances for a floating rotor? The service manual only addresses rotor thickness and lateral runout, but doesn't mention this situation as far as I can tell.
PS:
This could defnately be mistaken by some for the dreaded "front end clunk", but its not... I upgraded to the new heavy-duty washer and inspected/adjusted the column assembly, and its tuned nicely.
Thanks for any input!
Tourer
Joined: May 2010
Posts: 348
Likes: 5
From: The mitten state
Every floating rotor I've ever had would "click or clunk" when the brake was first applied.
That is the nature of a "FLOATING" rotor, the disc is not tightly fixed, ie.
FLOATING! They will have some amount of "play" in the disc. That is also why a floating rotor os said to have an advancage over a "fixed" disc.
The "play" allows the disc to be evenly centered in the caliper when the brakes are applied! And the seperation of the "disc" from the mounting plate help to disapate heat and evenly cool and heat the braking disc.
It's normal.
That is the nature of a "FLOATING" rotor, the disc is not tightly fixed, ie.
FLOATING! They will have some amount of "play" in the disc. That is also why a floating rotor os said to have an advancage over a "fixed" disc.
The "play" allows the disc to be evenly centered in the caliper when the brakes are applied! And the seperation of the "disc" from the mounting plate help to disapate heat and evenly cool and heat the braking disc.
It's normal.
Last edited by FBRR; Nov 18, 2010 at 12:54 PM.
Tourer
Joined: Dec 2006
Posts: 270
Likes: 1
From:
'clunking' that isn't normal
This may not be what you're describing, but if you hear a clunking that is associated with the rotation of the wheel it might be the buttons of the floating rotor hitting the edge of the brake pads. A simple fix is to champfer the brake pad leading edges. When I changed out my rotors to metalmatrix composites i ran into this. No big deal, just worried me when I heard it. Easy fix. Jay
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
One of the reasons for the invention of floating rotors is to isolate the transfer of braking heat into the hub and wheel bearings, as well as to reduce distortion of the rotors under hard braking. What you describe Stomper is happening while everything is 'cold', but it is possible, if you could get your ear down there at speed, that when everything is at operating temperature the heat-build up expands everything and all goes quiet!
I recently fitted a new rear floating rotor to my Glide and that is slightly loose. I also have floating rotors on the front and they haul all 1200 pounds of wife, luggage and I to a stop very well! Ride on and enjoy.
I recently fitted a new rear floating rotor to my Glide and that is slightly loose. I also have floating rotors on the front and they haul all 1200 pounds of wife, luggage and I to a stop very well! Ride on and enjoy.
Last edited by grbrown; Nov 19, 2010 at 03:02 AM. Reason: Grammar!
Thread Starter
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Tourer
Joined: Jan 2010
Posts: 304
Likes: 1
From: Woodburn, OR. USA
Thanks for the replies! I'm an HVAC-R mechanic and pretty well versed in the effects of physics on mechanical equipment. All of your replies have validated my observations and "theories" on the floating rotor design. I figured there should be some sort of tolerance for "freeplay" between the hub and rotor, but didn't know how much is "acceptable".
The "buttons/rivets" aren't hitting anything (like the pads), everything works like it should, its just that I could actually see the movement (and "clunk") between the two components when moving everything by hand. I'm just glad I don't have to shell out for a new rotor... or anything else for that matter!
Thanks again for the input everyone!
The "buttons/rivets" aren't hitting anything (like the pads), everything works like it should, its just that I could actually see the movement (and "clunk") between the two components when moving everything by hand. I'm just glad I don't have to shell out for a new rotor... or anything else for that matter!
Thanks again for the input everyone!
Road Master
Joined: Nov 2009
Posts: 1,218
Likes: 0
From: Yakima WA
I have googled the snot out of this issue, and have found everything from, "it's normal" all the way to, "dude get that changed out ASAFP!"
Is it normal for the front floating rotor to have a bit of "radial play" from the "isolating rivets" and hub? With the bike suspended on my HF lift I noticed that the rotor slightly "clunks" when I apply the front brake and put "rotational pressure" back and forth by hand on the wheel. I could see where the rotor was gripped tight by the pads/caliper, and the "isolating rivets" and hub had a bit of "radial play" making the "clunking".
I have always noticed it for a short while when I first take the bike out for a ride "cold", but then don't notice it after everything is "warm". I suspect the rotor gets warmed up from friction against the pads and expands a bit taking up any slack in the assembly, hence the "loose tolerances". The front brake works great (knock on wood) there is no sign of excessive wear on the rotor and its not warped, etc. but then again I'm not a brake rotor expert. Is this within normal tolerances for a floating rotor? The service manual only addresses rotor thickness and lateral runout, but doesn't mention this situation as far as I can tell.
PS:
This could defnately be mistaken by some for the dreaded "front end clunk", but its not... I upgraded to the new heavy-duty washer and inspected/adjusted the column assembly, and its tuned nicely.
Thanks for any input!
Is it normal for the front floating rotor to have a bit of "radial play" from the "isolating rivets" and hub? With the bike suspended on my HF lift I noticed that the rotor slightly "clunks" when I apply the front brake and put "rotational pressure" back and forth by hand on the wheel. I could see where the rotor was gripped tight by the pads/caliper, and the "isolating rivets" and hub had a bit of "radial play" making the "clunking".
I have always noticed it for a short while when I first take the bike out for a ride "cold", but then don't notice it after everything is "warm". I suspect the rotor gets warmed up from friction against the pads and expands a bit taking up any slack in the assembly, hence the "loose tolerances". The front brake works great (knock on wood) there is no sign of excessive wear on the rotor and its not warped, etc. but then again I'm not a brake rotor expert. Is this within normal tolerances for a floating rotor? The service manual only addresses rotor thickness and lateral runout, but doesn't mention this situation as far as I can tell.
PS:
This could defnately be mistaken by some for the dreaded "front end clunk", but its not... I upgraded to the new heavy-duty washer and inspected/adjusted the column assembly, and its tuned nicely.
Thanks for any input!
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Floating front rotor knock
I have googled the snot out of this issue, and have found everything from, "it's normal" all the way to, "dude get that changed out ASAFP!"
Is it normal for the front floating rotor to have a bit of "radial play" from the "isolating rivets" and hub? With the bike suspended on my HF lift I noticed that the rotor slightly "clunks" when I apply the front brake and put "rotational pressure" back and forth by hand on the wheel. I could see where the rotor was gripped tight by the pads/caliper, and the "isolating rivets" and hub had a bit of "radial play" making the "clunking".
I have always noticed it for a short while when I first take the bike out for a ride "cold", but then don't notice it after everything is "warm". I suspect the rotor gets warmed up from friction against the pads and expands a bit taking up any slack in the assembly, hence the "loose tolerances". The front brake works great (knock on wood) there is no sign of excessive wear on the rotor and its not warped, etc. but then again I'm not a brake rotor expert. Is this within normal tolerances for a floating rotor? The service manual only addresses rotor thickness and lateral runout, but doesn't mention this situation as far as I can tell.
PS:
This could defnately be mistaken by some for the dreaded "front end clunk", but its not... I upgraded to the new heavy-duty washer and inspected/adjusted the column assembly, and its tuned nicely.
Thanks for any input!
Is it normal for the front floating rotor to have a bit of "radial play" from the "isolating rivets" and hub? With the bike suspended on my HF lift I noticed that the rotor slightly "clunks" when I apply the front brake and put "rotational pressure" back and forth by hand on the wheel. I could see where the rotor was gripped tight by the pads/caliper, and the "isolating rivets" and hub had a bit of "radial play" making the "clunking".
I have always noticed it for a short while when I first take the bike out for a ride "cold", but then don't notice it after everything is "warm". I suspect the rotor gets warmed up from friction against the pads and expands a bit taking up any slack in the assembly, hence the "loose tolerances". The front brake works great (knock on wood) there is no sign of excessive wear on the rotor and its not warped, etc. but then again I'm not a brake rotor expert. Is this within normal tolerances for a floating rotor? The service manual only addresses rotor thickness and lateral runout, but doesn't mention this situation as far as I can tell.
PS:
This could defnately be mistaken by some for the dreaded "front end clunk", but its not... I upgraded to the new heavy-duty washer and inspected/adjusted the column assembly, and its tuned nicely.
Thanks for any input!
Road Warrior
Joined: Sep 2016
Posts: 1,634
Likes: 578
From: Cape Coral Fl
Clean and rotate the buttons. Good degreaser and a spish splash of spray WD . Should be maintained periodically. Cafe racers do it all the time. Google it
Last edited by Tileman2692; Jul 4, 2020 at 04:57 PM.