Warped Front Rotors- machine or replace?

[tubebender]

Well, I'm going to be the sole naysayer of the group and contend that you may not have warped rotors, but do have an uneven deposit of friction material on the disc.
I find it very hard to believe that you have subjected your brakes to such severe abuse that disc temps have exceeded design specification.
There may be a a few owners on this site that can, but most of us mere mortals don't have that level of talent.

I cannot find a relevant article that applies specifically to motorcycle discs, but plenty of automotive related FAQs address this issue.
http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

So, have a brief read, and you may be able to apply this quote from the above article.
"If only a small amount of material has been transferred i.e. if the vibration is just starting, vigorous scrubbing with garnet paper may remove the deposit. As many deposits are not visible, scrub the entire friction surfaces thoroughly. Do not use regular sand paper or emery cloth as the aluminum oxide abrasive material will permeate the cast iron surface and make the condition worse. Do not bead blast or sand blast the discs for the same reason."

 

[Super10NJ]

Hey all, I do track days on sport bikes and I am a heavy braker, if the cool down lap doesn't cool the rotors down sufficiently and it often doesn't I'll always spin the wheels (front wheel really) when on the stands to keep the heat from warping the rotors. The reason the heat will warp the disc is that the part of the rotor that remains under the pads cools much slower than the rest of the disc and that causes the metal to contract at different levels.

Obviously most of us won't be doing hot laps around the neighborhood just before we park the S10, however even if you built up a little bit of heat in the rotors and then park it over enough times it could have an overall effect. I'd think most of have the same route home and some of us might have a few point of heavy braking before it's parked moments later. Just a thought.

 

[EricV]

Well, I'm going to be the sole naysayer of the group and contend that you may not have warped rotors, but do have an uneven deposit of friction material on the disc.
I find it very hard to believe that you have subjected your brakes to such severe abuse that disc temps have exceeded design specification.
There may be a a few owners on this site that can, but most of us mere mortals don't have that level of talent.

I cannot find a relevant article that applies specifically to motorcycle discs, but plenty of automotive related FAQs address this issue.
http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

So, have a brief read, and you may be able to apply this quote from the above article.
"If only a small amount of material has been transferred i.e. if the vibration is just starting, vigorous scrubbing with garnet paper may remove the deposit. As many deposits are not visible, scrub the entire friction surfaces thoroughly. Do not use regular sand paper or emery cloth as the aluminum oxide abrasive material will permeate the cast iron surface and make the condition worse. Do not bead blast or sand blast the discs for the same reason."

I have de-glazed auto rotors many times with this method, with success. Being the internet, we don't really know the condition of the OP's rotors, only what he can share with us. That said, there is zero down side to trying the garnet paper process first. Most auto parts stores will carry sheets of garnet paper. Do some reading and then go get some. You can do this with the wheel(s) on the bike, but it's a lot easier off the bike, imho. You'll need to use some good elbow grease while doing this, "vigorous" is not an understatement.

 

[yz454]

I don,t think they are warped . Scotch bright the pads and disc .

 

[Mtbjay]

Good news! My moto buget was blown in juniors Christmas gifts, so this info is welcome indeed! I'll head down to my local Ace Hardware store and pick me up some garnet paper and give it a go. The vibes are quite minimal, as well as the wear, so it'd be a shame to begin replacing anything at this early juncture. I'll be sure to let y'all know how it worked out.

Again, thanks to everyone for your input and offer to help! You guys are alwright!

 

[Lutsie]

Sounds good mtb. Good luck, and I'm wishing the best/cheapest for you.

 

[Mtbjay]

UPDATE:

While I dragged my feet on the matter, but finally took some abrasives to my rotors as suggested. The garnet paper in 200 grit proved hard to find locally, so I picked up some "Scotch-brite" type scouring pad at Napa instead. Some 30 minutes of vigorous rubbing later and I was ready to test ride the bike. Fortunately for me, I'd say it made an 80% improvement in the pulsating brake I had been experiencing. Upon my return, I took to the rotors once more, for another 15 minutes of scrubbing and rubbing. I'm hopeful that will do the trick for now. Must have been the irregular deposit of brake pad compound as suggested in the "Stop-tech" brake guru's article (as noted the link posted here in the replies). My rear rotor got the same treatment and is now less touchy. I thought i'd remove the pads and give them a cleaning too, but decided the results from just scouring the rotors was sufficient.

On the subject of garnet paper, everything I found stated it was for wood on the packaging. While I readily found, 3M's "made for metal" abrasive paper in super fine grit at automotive parts stores and wondered if this was safe to use on motorcycle rotors. Because… as mentioned in the Stop-tech article, the concern in using common (non-garnet) sand paper is that the aluminum oxide abrasives could penetrate the rotor material and make matters worse. However, I noted the article pertained specifically to automotive brakes, not motorcycle brakes. Automotive rotors have a high iron content (I believe), and are different from the stainless steel (or high-carbon steel) material motorcycle rotors are typically formed with. I am happy with the results front the "made for metal" Scotch-brite pads, but wondered if the for metal sand paper in, say 200 grit, might have been a more efficient choice. Either way, the bike rides (and brakes) much nicer now.


Thx all!


P.S In a 600 mile trip around the Olympic Peninsula, the pulsation came back. Will try something more abrasive next.

 

[Rasher]

As an expert on warping discs I think the S10 ones are pretty good.

On my 2008 ZZR 1400 (ZX14R) I got through two sets under warranty with both warping in under 5k, both times they went during a two-up tour of mountains, my guess being repeated use on twisty downhill sections two-up just pushed them too far. I then fitted PFM's (as used back in the day by Steve Hislop at the Isle of Man) and they managed two more tours with no problems, when I sold the bike I sold the discs to a mate who had warped his - and they are still going strong 4 years later.

The S10 managed two long Alpine tours two-up, plus a couple more tours solo and have now clocked up almost 20k, and the lack of reports of knackered discs here suggest they are generally pretty good as OE equipment goes

 

[radbrad511]

Kind of late to the party but, my brakes were pulsing under moderate/hard braking. Thought I might need new rotors after 30000 miles of spirited riding. Pulled the calipers and pads. Scrub roters with purple Scotchbrite pad. Scrub pad retaining pins until clean/smooth. Sanded pads (EBC HH) Cleaned calipers with toothbrush/rag. Light coat of grease on pins, re-assembled...FIXED!! Brakes like new again, minimal investment of time. ::26::

 

[WJBertrand]

I've just come from the dealer where my front rotors were replaced under warranty. I tried all the cleaning and scrubbing techniques to no avail. I don't know whether the rotors were warped of fell victim to uneven pad material deposition phenomenon but I do know the new ones are sweet. Braking is smoother than when the bike was new. The service manager at the dealer that performed the replacement emphasized the importance of doing a proper bedding-in of the brakes on new bikes and said they do this as part of their new bike set-up. Looking at my odometer it seems he put a good 7-8 miles on the bike doing this. The dealer where I bought my bike certainly didn't because it had less than a mile on it as I rode it away at delivery. The bike now brakes more smoothly and powerfully than when new.

 

[markjenn]

I've just come from the dealer where my front rotors were replaced under warranty. I tried all the cleaning and scrubbing techniques to no avail. I don't know whether the rotors were warped of fell victim to uneven pad material deposition phenomenon but I do know the new ones are sweet. Braking is smoother than when the bike was new. The service manager at the dealer that performed the replacement emphasized the importance of doing a proper bedding-in of the brakes on new bikes and said they do this as part of their new bike set-up. Looking at my odometer it seems he put a good 7-8 miles on the bike doing this. The dealer where I bought my bike certainly didn't because it had less than a mile on it as I rode it away at delivery. The bike now brakes more smoothly and powerfully than when new.

My bet would be that you had defective rotors from the start and they problem just amplified with miles. Glad its sorted.

- Mark