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  1. #1
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    brake rotor direction

    I recently installed new avid crs... I mistakenly installed the front rotor backwards. I tried to remove it but inadvertently stripped two of the mounting screws. What would happen w/ the rotor facing the wrong way? If need be I can remove the screws w/ a stripped screw tool. Just curious.

    thanks

  2. #2
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    backwards rotor

    I'm pretty sure the direction is due to the sweep of the spines,or whatever you call them.
    I would certainly turn them around the right way.If you already have a set of easy-outs go ahead.Just be very careful drilling it out.Other wise it would be cheaper and safer to take it to the shop.

  3. #3
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    Quote Originally Posted by Montanamtb
    I recently installed new avid crs... I mistakenly installed the front rotor backwards. I tried to remove it but inadvertently stripped two of the mounting screws. What would happen w/ the rotor facing the wrong way? If need be I can remove the screws w/ a stripped screw tool. Just curious.

    thanks
    Drill out (off) the bolt heads. Remove the rotor. Grab the bolt stubs with vicegrips and remove.

    But if you were able to strip the heads of new bolts, take it to the shop.
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  4. #4
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    Just for S and Gs what would happen if I did not flip the rotor? I'm going to, but curious as to why they run the other way.

  5. #5
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    I would suggest that the machined 'spokes' are designed to be rotationally strong when the rotor is rotating in the direction indicated by the arrow etched on the rotor.

    If you run it the other way, the likelihood of it breaking, sending jagged bits of hot metal into your Achilles tendon, as you apply the brakes while going 30 mph down a chute strewn with pointy rocks, is much greater. When you phone SRAM to complain, they are going to tell you it was mounted wrong, and are very sorry that your foot had to be amputated.

  6. #6
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    The spokes keep outward force against the braking track when braking, keeping it inflated, or pushed outward. If the rotor gets hot and soft, and the spokes are backwards, it could collapse inward. Probably not an issue unless things get critical.
    Last edited by 1niceride; 09-03-2010 at 08:26 PM.

  7. #7
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    I picked up a set of disc screws with allen heads instead of t-25 on ebay. They were only 6-7 bucks for 12, and I like the heads better.

  8. #8
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    t25 has ( for a given metal composition ) a much stronger engagement ( less chance of stripping ) with the tool than allen ( hex) type ones.

  9. #9
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    Quote Originally Posted by Montanamtb
    Just for S and Gs what would happen if I did not flip the rotor? I'm going to, but curious as to why they run the other way.
    I would say nothing. But you'll probably get sick of people asking why it's like that.

    As mentioned, button head cap screws have the weakest and easiest to round out tool socket you will ever find. Good luck getting them out when they've been in there a while.
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
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  10. #10
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    You are screwing around with the space/time continuum.

    Sort of like crossing the streams of the Ghostbusters proton accelerators.

    Just to be safe, better get some kneepads and make sure your bike helmet is in good shape.

  11. #11
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    I have a set of rotors running backwards, am a clyde, who uses formula the one brakes and rides the occasional DH course.

    If I can't break them!

    Is it a silly ultralight rotor or a normal one, I just use superstar.
    Why would I care about 150g of bike weight, I just ate 400g of cookies while reading this?

  12. #12
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    Quote Originally Posted by slidecontrol
    t25 has ( for a given metal composition ) a much stronger engagement ( less chance of stripping ) with the tool than allen ( hex) type ones.
    The problem is it seems that because of that bolt makers always make the torx out of a softer metal and they always end up stripping easier than allen heads in the real world.

    Ask any Jeep owner how much stronger torx heads are than allen heads.

  13. #13
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    It's the stock rotor that comes w/ the avid cr

    I'm sure it will be just fine. I'm about 150lbs and xc rider. I will try to get em out. If not will just leave as is.

  14. #14
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    Quote Originally Posted by tussery
    The problem is it seems that because of that bolt makers always make the torx out of a softer metal and they always end up stripping easier than allen heads in the real world.
    No.
    Torx rotor bolts are as hard as bolts get in that size. An M5 buttonheadcapscrew (aka allen head) has a 3mm hex in it. They are pathetically easy to round out even when conditions are perfect.
    In the real world torx are better and that's why they're used.

    Quote Originally Posted by tussery
    Ask any Jeep owner how much stronger torx heads are than allen heads.
    Ask any mountainbiker how relevant jeep bolts are to their disc rotors.
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  15. #15
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    As a Jeep owner and a former machinist(I also stayed at a Holiday Inn once), Torx head bolts are much better than allen head bolts because there is a larger surface area for the tool to engage. In all my years of Jeep experience I NEVER stripped a torx bolt probably because I use quality(Snap-On,MAC.Etc,)tools and most importantly correct procedures.The same goes for bike repairs, Use quality tools and correct procedures.

  16. #16
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    Didn't mean to highjack the thread by pointing out the availability of the hex heads, but it does make for some interesting reading. I have both on different set of wheels and have never stripped either.

    Got the allens because they were cheap. Here's a link. The seller mentions some possible benefits. I'm not connected with the seller and don't know if they are better or not. I just prefer the hex heads.

    http://cgi.ebay.com/Stainless-Steel-...item3594d494c1

  17. #17
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    Quote Originally Posted by rlouder
    Didn't mean to highjack the thread by pointing out the availability of the hex heads, but it does make for some interesting reading. I have both on different set of wheels and have never stripped either.

    Got the allens because they were cheap. Here's a link. The seller mentions some possible benefits. I'm not connected with the seller and don't know if they are better or not. I just prefer the hex heads.

    http://cgi.ebay.com/Stainless-Steel-...item3594d494c1
    316 stainless is very soft, much softer than black steel cap screws or the torx bolts you normally get.
    I wouldn't use those on any of my bikes. I have used low head cap screws, but those have a 4mm hex in the head and are grade 12.9. Those have a 3mm hex and are the equivalent of grade 6.8, they are half the strength and hardness.
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  18. #18
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    I say....

    Quote Originally Posted by Montanamtb
    I recently installed new avid crs... I mistakenly installed the front rotor backwards. I tried to remove it but inadvertently stripped two of the mounting screws. What would happen w/ the rotor facing the wrong way? If need be I can remove the screws w/ a stripped screw tool. Just curious.

    thanks
    Give a brand new good quality tool a try in the bolt, and go super slow and sure to try and back it out. Torx is really touchy about having a fresh, unchewed up tool. I like to use one of those drill bit tip type torx tools (do not use it in a drill!!) in a good quality hand ratchet, so you have something you can grip and be super steady and firm while you work.

  19. #19
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    Quote Originally Posted by Montanamtb
    I recently installed new avid crs... I mistakenly installed the front rotor backwards. I tried to remove it but inadvertently stripped two of the mounting screws. What would happen w/ the rotor facing the wrong way? If need be I can remove the screws w/ a stripped screw tool. Just curious.

    thanks
    I use a mini hacksaw to cut a slot for a flat screwdriver. I have a screwdriver with the blade ground to fit the slot tightly. A light tap to fit the driver in and never had to go further with more invasive actions. I've had to slot many when I used the 316 stainless screws. They really do suck...

  20. #20
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    ^ same method but with a dremel and cutoff disk.

  21. #21
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    I've run a lot of discs the "wrong" way because I think they look better that direction. It totally doesn't matter.
    "It looks flexy"

  22. #22
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    Actually you should run them the proper direction, since the struts perform better under under compression than tension, else warping conditions (very rare) can happen.

    I did run some Ashima backwards for some time, and never had an issue?

  23. #23
    ballbuster
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    I think...

    Quote Originally Posted by Montanamtb
    I recently installed new avid crs... I mistakenly installed the front rotor backwards. I tried to remove it but inadvertently stripped two of the mounting screws. What would happen w/ the rotor facing the wrong way? If need be I can remove the screws w/ a stripped screw tool. Just curious.

    thanks
    direction of the rotor has to do with how the rotor expands unevenly when it gets hot. It might make a difference in safety if you get the rotor super hot to the point of failure, in how the splines keep the rotor from failing, and totally dead stopping the wheel as it gets jammed.

    Prolly more paranoia than reality. I would think the caliper would vapor lock long before the rotor failed.

  24. #24
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    Quote Originally Posted by pimpbot
    direction of the rotor has to do with how the rotor expands unevenly when it gets hot. It might make a difference in safety if you get the rotor super hot to the point of failure, in how the splines keep the rotor from failing, and totally dead stopping the wheel as it gets jammed.

    Prolly more paranoia than reality. I would think the caliper would vapor lock long before the rotor failed.
    Actually a brand I won't name had issues with them being run backwards, it was only in their 203mm sizes, and obviously from some pretty heavy duty DH types users. Better safe than sorry?

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