When to replace Rotors?

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When to replace Rotors?

Post by 0face » Fri Aug 02, 2019 8:02 pm

I’m posting this here so the information gets added to the library in addition to getting answers for myself.

So, what’s the spec for replacing front and rear rotors?

What tool do you need to measure them?

If the rotors are below spec, would you go with OEM replacements or a decent aftermarket?

If rotors are being replaced, any advice on technique? I’d hate to strip one of those bolts.

Thanks.
Last edited by 0face on Fri Aug 02, 2019 8:02 pm, edited 1 time in total.
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Re: When to replace Rotors?

Post by raYzerman » Fri Aug 02, 2019 8:32 pm

The Yamaha wear limit is 4mm, measure with a micrometer. You could likely run them a tad thinner, but the concern is if too thin they will shatter or not dissipate heat fast enough. No worries if you're close until you get new ones.
OEM's are just fine, but I had a spare set of wheels needing a set. I ordered these from a Chinese supplier, the quality is very good. The slots seem to dissipate heat a little better, and I think they are every bit as good if not a teeny tad better when braking (I am using OEM pads). They look good and a pair can be had as cheap as one EBC or Galfer. I have many thousand miles on them, no issues at all.
As for the bolts, Yamaha states replace them, however I believe that is because they come precoated with loctite. The torque is small, so I don't think there is any issue with re-using them once if you apply loctite. You may need an impact driver to remove the originals.
Link to rotors similar to what I bought.... also available with gold or yellow hubs, I'm of the belief there is one supplier in China making them but there are many resellers.
https://www.ebay.com/itm/For-Yamaha-YZF ... SwIIpdKS8s
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Re: When to replace Rotors?

Post by FJRoss » Fri Aug 02, 2019 9:05 pm

Great answer.
I might add that some pads have been particularly aggressive toward rotors and cause excessive wear. Carbone Lorraine have been mentioned as problematic. Any time there is obvious physical damage to the rotors (grooves, uneven wear), replacement should be considered even if not below thickness spec. (Some have complained about the EBC HH pads but I like them - especially at half the OEM price)

Regarding removal of the OEM bolts, a little applied heat works wonders. I have a mini butane torch that can direct heat to the bolthead without heating and possibly warping the rotor.
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Re: When to replace Rotors?

Post by NTXFJR » Fri Aug 02, 2019 10:04 pm

I replaced my front rotors a couple of years ago because or warping. I reused the 6 ea. button head bolts which isn't an issue imo except that the silver paint on them got corrupted and they are now rusty. Not a big deal to clean them up and treat the rust but it might be easier to just replace them with new ones.
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Re: When to replace Rotors?

Post by ionbeam » Sat Aug 03, 2019 8:27 am

ionbeam wrote:
Sat May 18, 2019 10:04 am
The EBC HH Sintered pads are made from a copper mix to manage heat better. Organic pads are softer, feel better and are more gentle on rotors, however, organic pads don't come close to sintered pads in heat management. The first H is for cold braking performance and the second H is for hot performance, the EBC pads have both ends covered. Copper is softer than the rotor material so the wear will favor the pad and not the rotor.

On my Honda the EBC HH pads initially had poor braking performance because my rotors were scored. After 50 miles or so the rotors were visibly polished and braking returned to what I had expected. Over the life of the pads my rotors became highly polished. After 80k miles of HH pads the rotors had a little ridge between the inner edge of the rotor and the area swept area by the pad. The rotors were still within spec for thickness.

One set of EBC HH pads won't kill your rotors. If you want to worry monitor the process take a micrometer or vernier to the rotors before installing the pads and write down the rotor thickness. Check periodically. I believe the minimum service spec for the front rotor is 0.16" and the rear brake is 0.18".

Edit to add: My Gen III at 24k miles with OEM pads the front rotor is 0.185 and the rear is 0.235.
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Re: When to replace Rotors?

Post by ionbeam » Sat Aug 03, 2019 10:16 am

NTXFJR wrote:
Fri Aug 02, 2019 10:04 pm
I replaced my front rotors a couple of years ago because or warping. I reused the 6 ea. button head bolts...
Do tell how you got the little buggers out.

I broke an Allen wrench trying to get them out. Even using a pneumatic impact wrench I had to use a lot of heat to get them to move. I used enough heat that I was concerned about the metal losing temper so replaced the screws.

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Re: When to replace Rotors?

Post by NTXFJR » Sat Aug 03, 2019 11:10 am

ionbeam wrote:
Sat Aug 03, 2019 10:16 am
NTXFJR wrote:
Fri Aug 02, 2019 10:04 pm
I replaced my front rotors a couple of years ago because or warping. I reused the 6 ea. button head bolts...
Do tell how you got the little buggers out.

I broke an Allen wrench trying to get them out. Even using a pneumatic impact wrench I had to use a lot of heat to get them to move. I used enough heat that I was concerned about the metal losing temper so replaced the screws.
I have a good set of hex bit sockets which tend to be harder temper and not round off as easily, and used a cheater pipe on it too iirc. Impacting on loctited smaller hardware such as button head cap screws is dicey as loctite offers a lot of initial resistance to torque. The bolt or hex tool can strip out, or the fastener can just snap off. A slow and steady application of force along with heat if necessary is safer in my experience.
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Re: When to replace Rotors?

Post by griff » Sat Aug 03, 2019 11:31 am

ionbeam wrote:
Sat Aug 03, 2019 10:16 am

I broke an Allen wrench trying to get them out. Even using a pneumatic impact wrench I had to use a lot of heat to get them to move. I used enough heat that I was concerned about the metal losing temper so replaced the screws.
Huh, when I replaced the rotors on my 03 I used a little hand impact driver with a hammer. All of them came out easy peasy. With NO heat.
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Re: When to replace Rotors?

Post by ionbeam » Sat Aug 03, 2019 11:41 am

It was my '04. The bit I broke was a short, hardened impact wrench bit. It's the only one I have ever broken regardless if working on my bike or car. These bits don't round off either and the bits are precisely sized. Should I ever need to do this again it'll be the slow 'n steady breaker bar and see how that goes.

(Marty runs off to find a long pipe to use on his wrench....)
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Re: When to replace Rotors?

Post by 0face » Sat Aug 03, 2019 11:56 am

The handle to my floor jack should be long enough... LOL

Additional dumb question... WTF are Galfer rotors sooo expensive... is there really that much of a difference for the riding we do?

Oh and another one.... why in the hell would anybody pay $195 for USED ones on ebay when I can get a set of new ones from Boats.net for $174? (front rotors)
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Re: When to replace Rotors?

Post by ionbeam » Sat Aug 03, 2019 12:33 pm

Have you ever over heated the OEM rotors?
Have you ever glazed your brake pads?
Have you ever cracked OEM rotors?
Has the brake lever gotten soft after a lot of brake use due to rotor heat?
Have you ever run your FJR hard enough that the OEM rotor couldn't achieve enough brake force to activate the ABS?
Has the weight of the OEM rotors ever caused you to have handling, stability or the tendency to stand up in corners issues?
The ABS software limits braking slip angle to 87%, the OEM pads and rotors could easily exceed this without the ABS limiting, if you can brake harder than OEM the ABS software will still activate and not allow more than a 87% slip angle.

Tell me again why you want to spend a lot of money and work for Galfer rotors...

Oh ya baby, the do look cool. And cool costs. :mrgreen:

BTW, great Ferengi skills if you can find $465 Galfer rotors for under $200.
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Re: When to replace Rotors?

Post by NTXFJR » Sat Aug 03, 2019 12:45 pm

griff wrote:
Sat Aug 03, 2019 11:31 am
ionbeam wrote:
Sat Aug 03, 2019 10:16 am

I broke an Allen wrench trying to get them out. Even using a pneumatic impact wrench I had to use a lot of heat to get them to move. I used enough heat that I was concerned about the metal losing temper so replaced the screws.
Huh, when I replaced the rotors on my 03 I used a little hand impact driver with a hammer. All of them came out easy peasy. With NO heat.
Hand impact driver with hammer blow works well too, maybe even better at times. Pneumatic impact gun on loctited smaller hex hardware can be an issue.
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Re: When to replace Rotors?

Post by ionbeam » Sat Aug 03, 2019 12:54 pm

NTXFJR wrote:
Sat Aug 03, 2019 12:45 pm
griff wrote:
Sat Aug 03, 2019 11:31 am
ionbeam wrote:
Sat Aug 03, 2019 10:16 am

I broke an Allen wrench trying to get them out. Even using a pneumatic impact wrench I had to use a lot of heat to get them to move. I used enough heat that I was concerned about the metal losing temper so replaced the screws.
Huh, when I replaced the rotors on my 03 I used a little hand impact driver with a hammer. All of them came out easy peasy. With NO heat.
Hand impact driver with hammer blow works well too, maybe even better at times. Pneumatic impact gun on loctited smaller hex hardware can be ARE an issue.
By far my adjustable torque air impact wrench has been a studly tool. Not a lot of use on the FJR but for car work it's been invaluable. Even the lug nuts on my current car is nutz at 140 Ft/Lbs.

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Re: When to replace Rotors?

Post by Hppants » Sat Aug 03, 2019 4:36 pm

I’ve had best luck with heavy lock tight on fasteners by using my solder iron to direct the heat and then quickly using a hand impact with a good fitting bit and my dead blow hammer
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Re: When to replace Rotors?

Post by ionbeam » Sat Aug 03, 2019 4:41 pm

Hppants wrote:
Sat Aug 03, 2019 4:36 pm
...dead blow hammer
ionbeam approved and recommended tool

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Re: When to replace Rotors?

Post by raYzerman » Sat Aug 03, 2019 4:53 pm

Two methods of softening or loosening bolts with loctite, heat (not too much) and a hand impact driver or tapping them, not an electric or pneumatic tool which wants to spin them fast a bit too early (but they can work). Tap them with a hammer first perhaps, but they are in there.
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Re: When to replace Rotors?

Post by Pterodactyl » Sat Aug 03, 2019 7:12 pm

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Re: When to replace Rotors?

Post by AuburnFJR » Sat Aug 03, 2019 9:16 pm

0face wrote:
Fri Aug 02, 2019 8:02 pm
I’m posting this here so the information gets added to the library in addition to getting answers for myself.

So, what’s the spec for replacing front and rear rotors?

What tool do you need to measure them?

If the rotors are below spec, would you go with OEM replacements or a decent aftermarket?

If rotors are being replaced, any advice on technique? I’d hate to strip one of those bolts.

Thanks.
For me the answer depends. If you stay with stock brake pads, then yes use OEM rotors. If you plan on using after martket brake pads, then get their rotors as they are matched to their brake pad compounds. Otherwise the after market brake pads will eat up the OEM rotors.
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Re: When to replace Rotors?

Post by FJRoss » Sat Aug 03, 2019 9:26 pm

AuburnFJR wrote:
Sat Aug 03, 2019 9:16 pm
0face wrote:
Fri Aug 02, 2019 8:02 pm
I’m posting this here so the information gets added to the library in addition to getting answers for myself.

So, what’s the spec for replacing front and rear rotors?

What tool do you need to measure them?

If the rotors are below spec, would you go with OEM replacements or a decent aftermarket?

If rotors are being replaced, any advice on technique? I’d hate to strip one of those bolts.

Thanks.
For me the answer depends. If you stay with stock brake pads, then yes use OEM rotors. If you plan on using after martket brake pads, then get their rotors as they are matched to their brake pad compounds. Otherwise the after market brake pads will eat up the OEM rotors.
I have never had any issue with the EBC HH pads on the OEM rotors. Can't remember when I first switched to the EBC HH on my '07 but I think it was around 60,000 miles and ran EBC until I sold the bike last year at 185,000 miles - still on the OEM rotors. No scoring and still within spec. (I agree with ionbeam on the OEM rotors - why go to anything else?)
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Re: When to replace Rotors?

Post by AuburnFJR » Sat Aug 03, 2019 11:32 pm

FJRoss wrote:
Sat Aug 03, 2019 9:26 pm
AuburnFJR wrote:
Sat Aug 03, 2019 9:16 pm
0face wrote:
Fri Aug 02, 2019 8:02 pm
I’m posting this here so the information gets added to the library in addition to getting answers for myself.

So, what’s the spec for replacing front and rear rotors?

What tool do you need to measure them?

If the rotors are below spec, would you go with OEM replacements or a decent aftermarket?

If rotors are being replaced, any advice on technique? I’d hate to strip one of those bolts.

Thanks.
For me the answer depends. If you stay with stock brake pads, then yes use OEM rotors. If you plan on using after martket brake pads, then get their rotors as they are matched to their brake pad compounds. Otherwise the after market brake pads will eat up the OEM rotors.
I have never had any issue with the EBC HH pads on the OEM rotors. Can't remember when I first switched to the EBC HH on my '07 but I think it was around 60,000 miles and ran EBC until I sold the bike last year at 185,000 miles - still on the OEM rotors. No scoring and still within spec. (I agree with ionbeam on the OEM rotors - why go to anything else?)
The experience I was describing is from what I saw at the race track. The riders that put in the after maket pads, destroyed their OEM rotors in short order. Granted the braking is much more to the limit on the track then anything you will do on the street.
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