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Old 09-17-2012, 04:02 PM   #1
Guaglione OP
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Rear brake rotor question

First of all, I did try a search for this question, to no avail, so here it goes:

The bolts, or hollow plugs that hold my rear brake rotor to the flange that bolts to the rear wheel have worn to the point that the rotor is now quite loose.

My question is this: Do I have to replace the entire rotor, or can I get better or OEM bolts, or what ever they are called. I've check the KTM fiche, and that only shows a full rotor.

Any help/advice would be appreciated.

Cheers,

Luca
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Old 09-17-2012, 10:42 PM   #2
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I have the same thing going on with mine at only 8000mi I have read some things on it, They are rivets and I was going to make a punch and put it in a press and try to tighten them up but first I want to talk to somebody at Brembo and see if you can remove them and replace with the pin & cir clip type
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Old 09-18-2012, 02:26 AM   #3
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The parts you are talking about are called floaters.

I am not aware if anybody makes them for the stock rotors but it's possible.
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Old 09-18-2012, 06:07 AM   #4
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are they dangerously loose or do they just rattle a bit?

When I had my S4R, I used 2 sockets and a hammer to make the fronts float.

Companies do make replacements. Though none are listed for KTM, I'm sure they match up with some other company. Here .

That's basically what you're looking for
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Old 09-18-2012, 07:04 AM   #5
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At 12,500 miles my rear rotor is loose as well. But the question is, how loose is too loose?
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Old 09-18-2012, 08:40 AM   #6
slidewayes
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Dont want to find out how loose is to much , Good find on the Floaters just need to find out dimensions
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Old 09-18-2012, 09:07 AM   #7
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Appears to be a common issue, mine was making alot of racket, and was very loose (movement to each side of a few mm). Had my rear rotor replaced under warranty, as it appears KTM recognizes this issue.
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Old 09-18-2012, 09:46 AM   #8
geometrician
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Laugh Rattlin' Rotors

Full-floating discs (as opposed to the semi-floaters newer LC8's come with stock) have enough play in the buttons & channels to allow the discs to move on their carriers, thus creating that "rattle" sound one hears when moving the bike around or working on the running gear.

There are safety limits to be sure on the amount of freeplay you should have, usually caused by the softer carrier (inner) wearing the (usually) half-moon cutouts by the buttons. Being (usually) circular the wear is spread and the buttons rotate so they wear evenly as well. Also, being round and not having right-edges mechanical stress is distributed in all directions. If you had square buttons you'd have something to worry about...

"Rattling" discs were the trickest thing next to a dry clutch conversion or slicks back in the day when I roadraced. Many of us would punch the buttons (riveted on production/OEM bikes as opposed to having c-clips over washers to retain them) to get the discs to move freely. That's the whole point of this system- the discs move to align themselves in the brake pads while rolling (99.999% of your riding time) which reduces rolling resistance, friction & wear- then when you apply the brakes they move slightly to take up whatever freeplay exists. There is no discernable time/distance lost as the distance the rotors move is measured in thousandths of an inch/hundredths of millimeter.

The more-solid rivets used on production brake systems for street use are analogous to the warning on the top of a to-go cup of coffee we see now- protects the motorcycle companies & dealerships from endless queries & "warranty"-type issues from a buying public. As a Service Manager we had to be careful what we said to customers- believe me there are some customers that can break an anvil so bikes (as with most things) are designed with them in mind Warranty replacements (as posted above) aren't a de-facto recognition of a problem... now everyone reading that post will want new rotors which will just drive up the cost of our parts and their new bikes at dealerships

My KLR650 had an AP-Lockheed front disc off of one of Kevin Schwantz's RG500s with a custom carrier to match my hub bolt pattern made by a friend who worked for Industrial Light & Magic (Lucasfilms ya know). The disc moved back and forth (radially) several millimeters with ease after about 10yrs of abuse but never gave me any problems. I eventually switched to an EBC 320mm semi-floater when I installed a new caliper as I had to make a new bracket for it anyway, plus I got a good deal on the disc (new) off Fleabay.

As long as the disc hasn't been hit to have caused its "looseness" I wouldn't worry about it- hey, they float now, and that's the point

If in doubt call EBC's Tech Line. They're probably as liability-minded as any other business and might not want to make a broad statement that could open them up to tort- hey they didn't build our brakes remember
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Old 09-19-2012, 09:43 PM   #9
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geometrician. seeing that you are a service guy maybe you can find out the run out that is aloud , out of 9 Brembo rotors I have now the rear on my 18" dirt wheel is by far the worst. Sure that it is my bad I have found that I steer with the rear a lot on the 990 my second question is lets find out a way to replace the buttons so not to drive up the cost of all parts( we all know how much KTM likes ther parts)
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Old 09-22-2012, 07:48 AM   #10
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I recently replaced my rear rotor for this reason. The play just got too much; about 4mm side to side movement. The real concern was that it was not an even movement around the rotor, i.e., a couple of the floaters were tight on one side. I suspect when offroading a rock hit the disc or something causing the uneven wear. The disc was 4.3mm thick, which is under the service limit anyway.

I only noticed all this as it started to eat the brake pads alive, chewing through a set of rears in 3,000 miles.

I moved to a floating disc on my road wheels, and wavy solid disc on my offroad wheels.
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Old 09-26-2012, 12:42 PM   #11
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Apparently KTM thought mine was too loose and have decided to replace it.
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Old 09-26-2012, 07:17 PM   #12
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Quote:
Originally Posted by Ladukebob View Post
Apparently KTM thought mine was too loose and have decided to replace it.

Are they doing this under warranty, or out of warranty yet free of charge ?

If yes to the second half of my above question, , it deserves mention, because
KTM is a small company and if they are doing the right thing it is worthy of praise.

In any case, if the floaters caused a failure and the result was a locked rear wheel,
that could bring with it more excitement than I usually want in my day.


.
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Old 09-26-2012, 08:03 PM   #13
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Quote:
Originally Posted by It'sNotTheBike View Post
Are they doing this under warranty, or out of warranty yet free of charge ?

If yes to the second half of my above question, , it deserves mention, because
KTM is a small company and if they are doing the right thing it is worthy of praise.

In any case, if the floaters caused a failure and the result was a locked rear wheel,
that could bring with it more excitement than I usually want in my day.


.
This is being done under warranty.
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Old 11-16-2012, 06:22 AM   #14
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Question Abs

So what is everybodys thoughts on ABS adding to the acceleration of the rear brake disc rattle? I haven't had my 990 Abs very long and I have found that I tend to be activating the rear ABS as I like to slide the rear into corners in the dirt,( I keep forgetting to turn the bloody ABS off). My bike has 18,000kls on it and my rear rotor is quite rattley. Had the same type of floating caliper mount on my old Cali Guzzi and it did well over 100,00kls and was still quite firm after 19 years, no ABS though.

I am taking the bike over to Boltons to see what they say.
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Old 11-18-2012, 01:51 PM   #15
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Thumb Feedback would be greatly accepted.

Quote:
Originally Posted by Dee Cee View Post
So what is everybodys thoughts on ABS adding to the acceleration of the rear brake disc rattle? I haven't had my 990 Abs very long and I have found that I tend to be activating the rear ABS as I like to slide the rear into corners in the dirt,( I keep forgetting to turn the bloody ABS off). My bike has 18,000kls on it and my rear rotor is quite rattley. Had the same type of floating caliper mount on my old Cali Guzzi and it did well over 100,00kls and was still quite firm after 19 years, no ABS though.

I am taking the bike over to Boltons to see what they say.
So, no one has any comments on this.
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