Pulsating brakes - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 17 (permalink) Old 06-29-2019, 06:01 AM Thread Starter
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Pulsating brakes

Have any of you had any issues with pulsating (front) brakes? Both me and a friend of mine got this after approx. 10.000 km on our RS's. I'm thinking the rotors/disks have "deformed" slightly thus creating this effect.

None of us do track-days, but we might be riding "harder" than the average Joe...but that should not matter much. (This bike is made for the track!) With a fairly new bike, the rotors should last longer than this.

I'm looking out there to find more people that have this issue, so I can claim it under warranty.
The local shop dismissed it, as brake-rotors are "consumables" (don't know the proper English word for this), but we will fight this.



-Stig

Last edited by Lego; 06-29-2019 at 06:58 AM.
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post #2 of 17 (permalink) Old 06-29-2019, 06:09 AM
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Disks should last longer than that unless youíre riding hard. You should be able to check the runout of the disk with a dial gauge or a steel rule.
One other possibility is that the steering head bearings need adjustment.
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post #3 of 17 (permalink) Old 06-29-2019, 07:38 AM
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Tell us more about the pulsating. Does it happen under light braking and increase with harder braking? The opposite of that? Does vehicle speed or road surface make a difference?

One trick to try: Aggressively clean the discs with emory cloth and steel wool then rubbing alcohol. Some say the brake pads leave deposits on the discs that can cause pulsing.

'61 Clubman's Gold Star, 2013 Daytona 675R (track bike), 2013 KTM 690 Duke, 2017 KTM SD GT, 2018 Street Triple RS.
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post #4 of 17 (permalink) Old 06-30-2019, 01:48 AM
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Much more likely to be pad material on the discs than the discs themselves being warped.
What is the pad condition?
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post #5 of 17 (permalink) Old 07-01-2019, 10:28 PM
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Pretty sure Ali-bear is correct.
Bedding the brakes in and normal riding deposits an even layer of
brake pad material on the discs. So stopping power is due to friction of pads on pad material, not pads on rotor steel like everybody since the beginning of time assumed.
One cause of "uneven" pad material distribution is riding hard, braking hard to get the brakes really hot, then stopping and holding the brake lever on. This keeps hot pads against a hot static rotor thus depositing a large chunk of pad material in that spot. You might be able to use Scotch Brite pads, steel wool, or sandpaper to carefully scrub the entire rotor surface (both sides). Then bed the brakes in the normal way.
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Last edited by OneEyeMan; 07-01-2019 at 10:30 PM.
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post #6 of 17 (permalink) Old 07-03-2019, 07:51 AM Thread Starter
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I have heard this theory before, but wouldn't this residue be removed when braking?
If it is possible to remove this with "Scotch Brite pads and steel wool" why wouldn't the (tremedous) force of braking also remove this residue?

Has any of you actually experienced this? ...and "polished" the disks/rotors with success?

Which leads me back to my original question: anyone else having this issue?
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post #7 of 17 (permalink) Old 07-03-2019, 09:44 AM Thread Starter
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I asked the shop to measure the disks, when they serviced the bike. Just picked it up, and this is the values they measured:
Front right: 0.15mm
Front left: 0.10mm

So the disks are slightly deformed, but these values are within the tolerances set by Triumph.

Last edited by Lego; 07-04-2019 at 05:55 AM. Reason: "Tolerance" is a better word than limit
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post #8 of 17 (permalink) Old 07-04-2019, 03:42 AM
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Quote:
Originally Posted by Lego View Post
<snip>

Which leads me back to my original question: anyone else having this issue?
Yes and it was head bearings. If the figures you quoted are disk runout then thatís well within tolerance and wonít cause pulsing.
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post #9 of 17 (permalink) Old 07-04-2019, 05:53 AM Thread Starter
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Quote:
Originally Posted by DonTheMan View Post
Yes and it was head bearings. If the figures you quoted are disk runout then thatís well within tolerance and wonít cause pulsing.
Thanks! Will look into that.
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post #10 of 17 (permalink) Old 07-04-2019, 07:08 AM
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If that doesn't do it scrub the pads with a ScotchBrite pad and brake cleaner and then a change of pads.
I've had this going on with Buells in the past and now with an 04 Sprint.
Time for me to bite the bullet and buy a fresh set of pads.
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