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Mechanical and Technical Mechanical and technical topics, help, and discussions

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  • 2 Post By MarvTravis
  • 1 Post By MarvTravis
  • 1 Post By lagwagonlead
  • 1 Post By Ryanthegreat1
  • 1 Post By Tripledij
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Sep 1st 2021, 06:57 AM   #1
 lagwagonlead's Avatar
 
  Mar 2016
  Pasco, WA

  FJ-09, Versys 650 LT, SV650, YCF 155 SM
Brake rotor cleaning

Looking for some advice on cleaning some brake rotors. I've hit them with brake kleen and a scotch brite pads, enough so that I've worn completely through a 3 pack of those scrubber pads. I've tried sanding the old brake pads to get rid of any gunk on them and eventually swapped them out with EBC HH pads. Absolutely no change in the braking. It feels like someone smeared grease on them, there is no initial bite but as they heat up it improves slightly. There is also a pulsating like it's grabbing/slipping as the rotor turns like the gunk on it isn't evenly spread. Should I just buy new rotors or is there a cleaning trick I'm not aware of?

Bike is a 2019 Versys 650 LT.
Sep 1st 2021, 08:01 AM   #2
 Riki5156's Avatar
 
  Jun 2018
  LaCenter Washington

  83 Suzuki GS 1100E
Sounds like warped rotors. NEW EBCs aren't very expensive.
Sep 1st 2021, 12:43 PM   #3
 Pavement Tested's Avatar
 
  Jan 2016
  Seabeck

  '08 GSX1300R, '06 GSX-R 750, '16 KTM 690 Duke, '07 XR650L
If your lever is pulsing in your hand I'd guess warped rotors as well. You can do a run out test of you have the tools to verify.

Does the bike have ABS?
Sep 1st 2021, 12:56 PM   #4
 lagwagonlead's Avatar
 
  Mar 2016
  Pasco, WA

  FJ-09, Versys 650 LT, SV650, YCF 155 SM
Quote:
Originally Posted by Pavement Tested
If your lever is pulsing in your hand I'd guess warped rotors as well. You can do a run out test of you have the tools to verify.

Does the bike have ABS?
I can't feel it in the lever, and it isn't super obvious, it's my wife's bike and she doesn't notice it at all. The much bigger issue is that I have to four finger squeeze to brake. Again she doesn't notice because she never slows down quickly so engine braking is sufficient 99% of the time. The bike does have ABS.
Sep 1st 2021, 03:38 PM   #5
 Pavement Tested's Avatar
 
  Jan 2016
  Seabeck

  '08 GSX1300R, '06 GSX-R 750, '16 KTM 690 Duke, '07 XR650L
Have the brakes been bled properly? Even the smallest but if air in the system will make a big difference.

I've found that bleeding ABS brakes is a huge pain in the ass and even when done properly the ABS pump still causes a soggy feeling. I bypassed the pump on my KTM because of this even after installing a Brembo RCS master.
Sep 1st 2021, 04:13 PM   #6
 lagwagonlead's Avatar
 
  Mar 2016
  Pasco, WA

  FJ-09, Versys 650 LT, SV650, YCF 155 SM
Yep, I did front and rear. The rear brake works very well. One thing I haven't tried is taking the calipers apart to clean them.

I noticed on the way home today that when holding the brake lever steady (not increasing or decreasing force), the longer it's held the more it brakes. Meaning you're having to squeeze hard to get it to start grabbing, then you have to start reducing force gradually as it starts working better. It's such a weird issue.
Sep 1st 2021, 05:43 PM   #7
 curve addict's Avatar
 
  Apr 2016
  Des Moines, WA

  ...1987 Yamaha FZR1000...
Symptoms point to both warped rotor and sticky caliper piston(s). While you're at it, change the brake fluid and be prepared to rebuild or replace the master cylinder as well.
Sep 2nd 2021, 12:05 AM   #8
 MarvTravis's Avatar
 
  Jan 2016
  Kirkland, WA

  Kawasaki ZX-14
If the bobbins that provide the interface between the brake disk carrier and the brake disk are not allowing the disk to ‘float’, that could be the problem of the brake pulsing. There’s a good video by Delboy’s Garage that describes how to clean and free the bobbins, so the disk is free to ‘float’. It’s an old video, but it clearly shows the procedure.



CAUTION: This procedure is applicable ONLY if the mating surface of the bobbins that interface between the carrier and the disk is CIRCULAR. I happen to have after-market rotors with bobbins that have flat parallel sides on the mating surfaces of the bobbins, and this type bobbin WILL NOT rotate. The concept with this type bobbin is that, as the disk heats up and expands, the flat-sided bobbin keeps the angular interface between the carrier and the disk tight where, otherwise, it would become loose. You want to make certain your bobbins have a circular interface between the carrier and disk before you start reefing on them. You should be able to determine this by gingerly trying to rotate one of the bobbins. If it rotates, you’re good to go with this procedure.
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Edited by MarvTravis on Sep 2nd 2021 at 12:11 AM
Sep 2nd 2021, 08:14 AM   #9
 lagwagonlead's Avatar
 
  Mar 2016
  Pasco, WA

  FJ-09, Versys 650 LT, SV650, YCF 155 SM
I've read about cleaning the bobbins and it's very likely the cause of the slight pulse I'm feeling. However I haven't bothered cleaning them because it wouldn't help at all with the lack of braking. I think I'm just going to buy new rotors to fix both issues. I was hoping there would be some magic I haven't tried, like hitting the rotors with a flame thrower or throwing them in a washing machine. I'll do rotors, pads, and clean the calipers at the same time just to be sure.
Sep 2nd 2021, 10:30 AM   #10
 MarvTravis's Avatar
 
  Jan 2016
  Kirkland, WA

  Kawasaki ZX-14
It's possibie the fork seals are leaking slightly, and contaminating the brake pads.
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Sep 2nd 2021, 02:09 PM   #11
 lagwagonlead's Avatar
 
  Mar 2016
  Pasco, WA

  FJ-09, Versys 650 LT, SV650, YCF 155 SM
Quote:
Originally Posted by MarvTravis
It's possibie the fork seals are leaking slightly, and contaminating the brake pads.
That was my first thought when they didn't have any braking force, I've had that happen more than once in the past. I couldn't find any sign of leaking, but that doesn't mean it didn't leak before and get embedded beyond cleaning.
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Sep 3rd 2021, 07:50 AM   #12
 
  Apr 2016
  WA

Sand blasting the rotors has fixed similar issues for me. Just the friction area, not the aluminum hubs and bobbins.

Scotch brite pads are not typically aggressive enough to remove brake pad material.
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Sep 3rd 2021, 03:56 PM   #13
 Tripledij's Avatar
 
  Jan 2016
  Custer WA

  Aprilia Tuono 1100 and Moto Guzzi V7 III Milano
This is what you are aiming for.




Tried to embed, dangit Dorna, oh well, just click on the watch on Youtube for a great brake demo.
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