Author Topic: Warped Rotors Clarification  (Read 1796 times)

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Offline Alekkas

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Warped Rotors Clarification
« on: June 13, 2015, 08:23:42 pm »
Hi all.  Just picked up an 08 with 16K miles on it ABS.  Good deal.  Test ride revealed heavy throbbing / rockinghorse pogo (good name for a band or a porn flick) on front brake.   He is buying me two OEM rotors from Kaw. 

All that is done.  I have searched and found various fixes on various threads.  From sand in the buttons? to other makes of rotors to different pads 

1) So, what is the collective's advice at this point - new oem rotors coming in.   2) Also, never did this job before, I assume it is straight forward?
Seagiant needs to post more!
'08 C14 / PGR  / IBA
Some ride reports:
http://leroylanes.blogspot.com/
On two wheels:

Offline jwh20

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Re: Warped Rotors Clarification
« Reply #1 on: June 13, 2015, 09:01:09 pm »
Note that the rotor bolts have thread locker on them.  I use an impact driver, even one of the electric ones will do, to facilitate removal.  If you don't have one try to heat the bolts with a blowtorch to soften the locker a bit.  If you just try to use a hex driver the bolt will often strip the head.

Use BLUE Loctite or similar to re-assemble.  Not RED which is permanent.

Also be sure you get any crud, residue, debris OFF the mating face of the wheel.  Even a tiny bit of contamination will cause the rotors to not sit flat and you'll have a runout problem.

Some people suggest you reduce the torque specification by 10% when using thread locker but neither Loctite or Kawasaki suggest this.  I don't do it either.
« Last Edit: June 13, 2015, 09:05:09 pm by jwh20 »
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Offline Buzzard

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Re: Warped Rotors Clarification
« Reply #2 on: June 14, 2015, 12:45:20 am »
Before removing the old rotors, take a rag soaked with Brake Clean or similar brake parts cleaner, and wipe the rotors as you spin the wheel. Sometimes when doing things like a tire swap, the person doing the work lays a greasy paw on one or both rotors. When the greasy spot goes through the pads, it pulses. I know from experience, had really bad pulsing and wiped my rotors, rotors amazingly straightened out. Now when I work on the front tire/wheel, I clean the rotor after it is installed.

Offline Alekkas

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Re: Warped Rotors Clarification
« Reply #3 on: June 14, 2015, 05:14:13 pm »
Thanks Buzzard gave it a try on your suggestion - still heapum bouncy - but a great ride this morning!

Maybe I'm asking the wrong question.  When I get the new rotors on, what can I do to lessen the odds of this happening again? 
Seagiant needs to post more!
'08 C14 / PGR  / IBA
Some ride reports:
http://leroylanes.blogspot.com/
On two wheels:

Offline jwh20

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Re: Warped Rotors Clarification
« Reply #4 on: June 14, 2015, 05:21:24 pm »
Thanks Buzzard gave it a try on your suggestion - still heapum bouncy - but a great ride this morning!

Maybe I'm asking the wrong question.  When I get the new rotors on, what can I do to lessen the odds of this happening again?

Are you sure they are warped?  Specifically, did you measure the run-out with a run-out gauge?  My personal experience is that these C14 rotors don't actually warp but folks blame any sort of uneven braking on "warp".
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Offline Scup

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Re: Warped Rotors Clarification
« Reply #5 on: June 14, 2015, 06:01:02 pm »
Aren't they floating type rotors ?

Hard not to measure a some/slight run out = it's hard to get the rotors to sit square in the carriers = isn't it ?

My Brembo rotors move easily and a solid .020".

Josh









Offline jwh20

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Re: Warped Rotors Clarification
« Reply #6 on: June 14, 2015, 06:53:43 pm »
Aren't they floating type rotors ?

Hard not to measure a some/slight run out = it's hard to get the rotors to sit square in the carriers = isn't it ?

My Brembo rotors move easily and a solid .020".

Josh

The service manual calls for a TIR of 0.15 mm or less.  Service limit is TIR of 0.3mm.
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Offline Alekkas

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Re: Warped Rotors Clarification
« Reply #7 on: June 14, 2015, 07:52:26 pm »
Thanks Buzzard gave it a try on your suggestion - still heapum bouncy - but a great ride this morning!

Maybe I'm asking the wrong question.  When I get the new rotors on, what can I do to lessen the odds of this happening again?

Are you sure they are warped?  Specifically, did you measure the run-out with a run-out gauge?  My personal experience is that these C14 rotors don't actually warp but folks blame any sort of uneven braking on "warp".

No, I have not yet.  Don't have a gauge here.  What other factors are you aware of that would cause a serious BIG bouncing?  ABS seems to be functioning properly per the light and owners manual. No error codes.  I inspected pads and they look to be in good shape.  What else should be inspected?  Open to any options I can be proactive on. 
Seagiant needs to post more!
'08 C14 / PGR  / IBA
Some ride reports:
http://leroylanes.blogspot.com/
On two wheels:

Offline jwh20

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Re: Warped Rotors Clarification
« Reply #8 on: June 14, 2015, 09:02:54 pm »
In my experience with C14 brakes, the actual warping is rare.  What seems to happen is that there is some corrosion that happens between the pads and the 4 faces of the rotors under those pads when the bike sits for a while.  It seems to be exacerbated by the pads being wet.

The net-net of this is that the corrosion area, which is invisible but can be felt if you rub your fingers across it, has different friction characteristics than the rest of the rotor and tends to grab the pads more than usual.  So there is a pulsating effect in the bars but not in the brake lever as you would with a warped disk.

If you elevate the front wheel and spin it by hand you can often hear the "rough" spot as it passes under the pads.

I've found that this can be eliminated by taking the rotors off and scrubbing them vigorously with a 3M Scotchbrite or similar paint removal disk in your drill.

I'm NOT saying it's not a warped disk, just that before you assume that's the problem measure the run-out with a gauge and be sure.
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Offline Mike

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Re: Warped Rotors Clarification
« Reply #9 on: June 14, 2015, 09:27:51 pm »
Alekkas,  The symptom on my Ultra Limited was a pogo effect when coming to a stop.  I use my front brake when stopping at a stop sign or red light and it was throwing me off balance since the rotors would hit that high spot then not when using very little lever pressure.  I had installed some Genuine Harley Black Teardrop polished rotors when I was blacking out the Harley.  They may have lasted all of 3k miles and they were of the floating design.  Took it to a local indy and we lifted the front and mounted up a dial indicator and they were out .018 on one side and .024 on the other.  HD would not replace so they are hanging on my garage wall and I installed Lyndall Racing Composite Lug drive rotors.  They probably weigh less than 2 lbs each if that. He gives a lifetime no warp warranty and man are they nice.  Anyway,  I did not know what was going on since I knew they were new.  Heck,  at times I thought why the heck can't I stop anymore. The minute I went to drop the feet it would pogo and we were 650 miles away at a bike ralley.  I replaced the pads, cleaned the calipers and still no good before I took it to the Indy.  I know it was not a Concours but brakes are brakes and symptons would be the same.  I was told that if you were braking hard to stop for a sudden red light or similar situation and you left the lever pulled in and not released it could warp the rotor while sitting there in that manner.  Hope you figure it out. Can be unnerving.

Also if Lyndall Racing has his zpads for a Concours give them a shot.  I have used them in many different brands of bike for years and they are as good as they get.
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Offline Alekkas

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Re: Warped Rotors Clarification
« Reply #10 on: June 14, 2015, 10:24:51 pm »
Well, thanks to both.  All good here.  The bike really rides nice.  Comfort level is there and the motor - well you know.

JWH, I certainly don't mind changing the pads and scrubbing the rotors so I will try that this week while waiting on the new rotors.  With 16K miles on it, I am sure the pads are near due anyway - plus I'll be able to write the change down on my garage wall along with all the fluids I changed today and know it was done. 

Mike, thanks for the input on preventing this in the future. Happily, I don't have to pay for them - this time.

I have all week to do the first attempt before my trip to the UP next weekend from far west Chicago burbs/rural.  If that doesn't work, hopefully the rotors will be in before my trip to CA that begins the following weekend.   
« Last Edit: June 14, 2015, 11:31:53 pm by Alekkas »
Seagiant needs to post more!
'08 C14 / PGR  / IBA
Some ride reports:
http://leroylanes.blogspot.com/
On two wheels:

Offline Alekkas

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Re: Warped Rotors Clarification
« Reply #11 on: June 23, 2015, 08:17:45 pm »
So, to wrap this up, it was indeed a bent / warped rotor.  One was bad the other still straight.  The seller really stepped up with some quality ebc rotors.  Greatly appreciated.  New front pads as well - all is good and smooth.
Seagiant needs to post more!
'08 C14 / PGR  / IBA
Some ride reports:
http://leroylanes.blogspot.com/
On two wheels:

Offline stevewfl

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Re: Warped Rotors Clarification
« Reply #12 on: June 23, 2015, 08:41:20 pm »
So, to wrap this up, it was indeed a bent / warped rotor.  One was bad the other still straight.  The seller really stepped up with some quality ebc rotors.  Greatly appreciated.  New front pads as well - all is good and smooth.

2nd to none  :great:
KiPass!