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Old 06-16-2011, 07:56 PM   #1
rideoregon OP
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Rear Rotor Replacement?

My 2009 F800 GS was in the shop today for a 12K mile checkup. I was told that my rear brake rotor was under minimum spec at 4.43 mm and should be replaced. The cost? $300 plus. I was none too thrilled to hear this and asked "how common is it for an F800 GS to need a new rear rotor at 12K miles?" The answer I got was vague. I decided not to have the work done. I want to gather more information and likely will replace the rotor myself possibly with an after market brand. Has anyone else had to replace their rotor this soon? I did a search and did not find discussion on this but surely this has come up. What are others experiencing with rear rotor wear/replacement? Any feedback is appreciated.
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Old 06-16-2011, 09:27 PM   #2
Bayner
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How many sets of pads have you gone through? If it's more than one, I would say it's at least plausible it needs replacing.
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Old 06-16-2011, 09:30 PM   #3
ebrabaek
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Quote:
Originally Posted by rideoregon View Post
My 2009 F800 GS was in the shop today for a 12K mile checkup. I was told that my rear brake rotor was under minimum spec at 4.43 mm and should be replaced. The cost? $300 plus. I was none too thrilled to hear this and asked "how common is it for an F800 GS to need a new rear rotor at 12K miles?" The answer I got was vague. I decided not to have the work done. I want to gather more information and likely will replace the rotor myself possibly with an after market brand. Has anyone else had to replace their rotor this soon? I did a search and did not find discussion on this but surely this has come up. What are others experiencing with rear rotor wear/replacement? Any feedback is appreciated.
That seems odd..... Unless you are dragging the rear brake off course. I just measured mine..... 7800 miles..... 4.98mm. You might want to measure it yourself for good measure.....

Erling
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Old 06-16-2011, 10:15 PM   #4
johngil
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I'm at 4.6 - 4.7 on the brokeback beemer with just under 18,000 miles. I believe I'm on my fourth set of pads. Lots and lots of dirt and some mud.
Pads were OEM, then Galfer black. Maybe a set of Galfer gold on now. I can't remember.
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Old 06-17-2011, 06:33 AM   #5
JRWooden
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I'm still on the original set @ 17K miles, but they will be gone before much longer. I have a set of Galfer Greens ready to slap on, I bought the greens as the pkg said the greens were the easiest on the rotors.

I've got 4.8 for thickness right now....
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Old 06-18-2011, 06:52 PM   #6
rideoregon OP
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I'm on my second pair of rear break pads having replaced the first set after 10.5K miles. I don't drag the brake. What I'm curious to know is what is typical mileage for replacing the rear rotor on the F8?
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Old 06-18-2011, 09:24 PM   #7
ScienceOfDirt
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What is the minimum spec?
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Old 06-18-2011, 10:04 PM   #8
itsatdm
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New is 5mm. wear limit is 4.5mm
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Old 06-19-2011, 05:07 PM   #9
JRWooden
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Originally Posted by ChiTown View Post
...

Maybe I don't ride hard enough.
Right .................
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Old 06-20-2011, 02:19 PM   #10
rideoregon OP
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The OEM rear rotor is $271.99 plus $1.59 ea. for the one time use bolts. Galfer sells a rotor for the F8, part # DF763W, MSRP-- $139.00. Much more like it! I'll be ordering the Galfer rotor from the local Cycle Gear along with a set of Galfer pads.
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Old 06-20-2011, 03:24 PM   #11
rideoregon OP
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Galfer misquoted the price. It's $186.00 not $139.00. Still better than $272.00 for the OEM.
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Old 11-19-2012, 04:00 PM   #12
Hayate
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A friend of mine was surprised by the ridge on my rear rotor so mentioned I better get it measured. If my crappy old caliper is right and I'm reading it correctly I'm down to .133 inches, or 3.38mm. Way under spec eh? I just put my 5th set of rear pads on at 42,907 miles (2nd-4th, 7459, 18,200, 32,971 so about 10k each).

So I'm wondering a couple things...

First off a line of questions about rotor wear. So 4 sets of pads burnt 1.62mm of rear rotor and I was supposed to replace it after .50mm used? By my math that means a bit into the 2nd set of pads I'd be out of spec on the rotor? Like 15k miles and the rotor is done for? Is that normal? Can I do anything to prolong my next rotors life?

The other set relate to the 4.5mm minimum spec. Why is that the minimum? Is it because the thinner the rotor gets the less it is able to absorb and dispense heat or is it because you need the width to get full pressure from the caliper? I don't sense a lack of rear brake power and mine is way past that point (I can easily get the ABS to engage using only rear brake on dry pavement and a rear Metzler Tourance for instance).

I guess if I'm going to be replacing these things every 15k miles or anywhere in between that and my current 43k miles I'm not willing to pay what is it, $300? The Galfer option sounds better but what type of comparable wear factor will I get there? Are there other options?

I love riding this thing, but I'm getting a bit overwhelmed this last riding season with the expenses involved in maintaining it... and I'm even doing it all in my garage now :(
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hat a great 40,000 mile adventure on the trusty F800GS. Looking forward to the next 40k.
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Old 11-19-2012, 04:04 PM   #13
Hayate
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Quote:
Originally Posted by rideoregon View Post
The OEM rear rotor is $271.99 plus $1.59 ea. for the one time use bolts. Galfer sells a rotor for the F8, part # DF763W, MSRP-- $139.00. Much more like it! I'll be ordering the Galfer rotor from the local Cycle Gear along with a set of Galfer pads.
Are you sure that's the Galfer Roter for the 800gs? I just searched on it and found it on Amazon for $167 but plugging in BMW F800GS '09 it replied, this product does not fit. That and the pic shows only 4 bolt holes...

Guess I'll search some more?

... More research confirmed that DF763W is our rear rotor... at least the catalog http://galferusa.com/catalog/ says "763" for the rear rotor. I guess the pic on amazon is just a stock photo of a Galfer wave rotor. I'm not sure why the match tool on Amazon says it isn't compatible. I'm pretty sure I'll order one.

Best price seems to be Amazon for $167 with free shipping btw... I'll come back and update this if it works out.
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ad·ven·ture 1.an exciting or very unusual experience.
W
hat a great 40,000 mile adventure on the trusty F800GS. Looking forward to the next 40k.
Minnesota Parallel "Twin" Cities GS Riders
Daniel Betlock Adventure Rider

Hayate screwed with this post 11-19-2012 at 05:03 PM
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Old 11-19-2012, 06:49 PM   #14
Hamish71
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try www.metalgear.com.au
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Old 11-19-2012, 08:13 PM   #15
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A 2009 with only 12k miles on it? That's also a problem!

As I see it, there's three common ways to wear out a rear rotor. Normal use high mileage, lots of dirt/mud riding or you're a tail dragger. Riders who start out in the dirt tend to use the rear brakes a lot on the street. Now I'm not looking to start a "how to ride" thread nor am I saying I'm all that, but you really don't need your rear brake on the pavement. It has little effect anyway. My F8 has 45k kms on it with the original pads and rotor that's barely worn. It's been to Alaska and back so it's far from being a poser. The front brakes have two discs and four pads which are a lot more effective for stopping and wear better. Not saying your a bad rider but take note of how much you use the rear.

To answer another question, the rotors have a minimum spec for a reason. If the rotor is thin AND the pads are really worn then you run the risk of blowing a puck and possibly locking the wheel. Rotors are often run past the limit but with thick pads. Under 4 mm is a bit excessive though, not worth the risk but YMMV.

I've seen riders trade in their bike with shot rear brakes then bring their new bike (different model) shortly after and have the same complaint. Problem follows the rider.

Just sayin'.
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