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  1. #1
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    Is using washers instead of a brake adapter an issue?

    i just built a new wheelset with a centerlock front hub so i upraded the front rotor from a formula 160mm to a shimano ice tech 180mm. the 180mm post mount shimano adapter left probably 3-4mm of the upper pad showing and not contacting the rotor. to get the most complete and best pad to rotor contact i had to ditch the adapter and shim it up with a bunch of washers around the CPS washers.

    the only other option i can think of would be finding an adapter that happens to fit (something like 175-177mm - does that exist?) or grind the 180mm adapter down. note there should be more than enough thread contact (about 3/4") between the fork and bolts as the bolts are fairly long.

    i am riding the breck epic next week so i am sure a front brake will come in handy. anyone think this will be an issue?

    Is using washers instead of a brake adapter an issue?-img_0909.jpg

  2. #2
    rebmem rbtm
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    What benefit are you getting from using the CPS washers the way that they are?

    Your pads were overhanging because only Avid brake calipers are meant to use CPS washers on the underside of them.

    http://techdocs.shimano.com/media/te...9830667774.PDF

    Is using washers instead of a brake adapter an issue?-p4pb4225465.jpgIs using washers instead of a brake adapter an issue?-p4pb5967362.jpg

  3. #3
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    Quote Originally Posted by cobba View Post
    What benefit are you getting from using the CPS washers the way that they are?

    Your pads were overhanging because only Avid brake calipers are meant to use CPS washers on the underside of them.
    the benefit of the CPS washers in there now is to allow an angle for the caliper so it sits in the right place on the rotor. the adapter has angled surfaces that handle that (as shown clearly in your pics). just shimming with washers and no CPS would have had the caliper at an angle that didnt match up the pads and rotor as nicely.

    when i had the adapter installed i was NOT using the CPS washers or any other washers. just the fork post mount>adapter>caliper and still the caliper was sitting "too high" on the rotor. once i got rid of the adapter i added them in for both extra spacing and for the angle issue mentioned above.

  4. #4
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    Shimano adapters are not meant to be used with the Avid CPS washers, they only use them ontop the brake caliper to let them head sit properly and in full contact applying even pressure. Also, they are designed specifically to work with Shimano calipers, so using them for another brand will require some adaptation most likely.
    Attached Thumbnails Attached Thumbnails Is using washers instead of a brake adapter an issue?-lfp_4366.jpg  

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  5. #5
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    Quote Originally Posted by LyNx View Post
    Shimano adapters are not meant to be used with the Avid CPS washers, they only use them ontop the brake caliper to let them head sit properly and in full contact applying even pressure.
    as i said above...

    when i had the adapter installed i was NOT using the CPS washers or any other washers. just the fork post mount>adapter>caliper and still the caliper was sitting "too high" on the rotor. once i got rid of the adapter i added them in for both extra spacing and for the angle issue mentioned above.


    the CPS washers i am using came with the shimano adapter. i am totally aware that they are meant to be used between the caliper and the bolt heads and NOT beneath the caliper. however, since that didnt work, i had to improvise and now i am asking if what i have now will be structurally safe to use.

  6. #6
    rebmem rbtm
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    Quote Originally Posted by LyNx View Post
    Also, they are designed specifically to work with Shimano calipers, so using them for another brand will require some adaptation most likely.
    That doesn't sound right, directly mount a Shimano brake caliper and a Formula brake caliper onto post mounts with a 160mm rotor and neither of them should overhang the rotor. A Shimano 180mm adapter should therefore space a brake caliper out for a 180mm rotor exactly the same way as any other 180mm adapter does.

    ,

  7. #7
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    Quote Originally Posted by cobba View Post
    That doesn't sound right, directly mount a Shimano brake caliper and a Formula brake caliper onto post mounts with a 160mm rotor and neither of them should overhang the rotor. A Shimano 180mm adapter should space a brake caliper out for a 180mm rotor exactly the same way as any other 180mm adapter does.

    ,
    what i have is a shimano CL 180mm rotor and a shimano 180mm adapter. the caliper is a formula but that shouldnt matter as LyNx said.

    looks like THIS GUY had the same problem i do. not sure if he found a solution.

    anyone other suggestions before i either live with it or start filing my adapter down?

  8. #8
    rebmem rbtm
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    Quote Originally Posted by honkonbobo View Post
    the benefit of the CPS washers in there now is to allow an angle for the caliper so it sits in the right place on the rotor. the adapter has angled surfaces that handle that (as shown clearly in your pics). just shimming with washers and no CPS would have had the caliper at an angle that didnt match up the pads and rotor as nicely.

    when i had the adapter installed i was NOT using the CPS washers or any other washers. just the fork post mount>adapter>caliper and still the caliper was sitting "too high" on the rotor. once i got rid of the adapter i added them in for both extra spacing and for the angle issue mentioned above.
    I thought that you must of been using the CPS washers on the adapter but apparently you weren't.

    Something strange seems to be going on with the adapter that you have but I have no idea what, I presume that you did have it on the right way around.

    I don't see any problem with your current washer stack & CPS washer stack, it's doing exactly the same thing as what an adapter should.

  9. #9
    rebmem rbtm
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    Quote Originally Posted by honkonbobo View Post
    what i have is a shimano CL 180mm rotor and a shimano 180mm adapter.
    I know what you have, I was merely saying that a Shimano caliper and a Formula caliper are both standard post mount calipers and the adapter shouldn't matter.

    Quote Originally Posted by honkonbobo View Post
    looks like THIS GUY had the same problem i do.
    Not unless you put washers between the adapter and the caliper.

  10. #10
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    Quote Originally Posted by cobba View Post
    I know what you have, I was merely saying that a Shimano caliper and a Formula caliper are both standard post mount calipers and the adapter shouldn't matter.
    just clarifying for LyNx or anyone else trying to help.


    Quote Originally Posted by cobba View Post
    Not unless you put washers between the adapter and the caliper.
    ya you are right on that one. i missed that he put the washers in the wrong place. not the case here. thanks


    Quote Originally Posted by cobba View Post
    I don't see any problem with your current washer stack & CPS washer stack, it's doing exactly the same thing as what an adapter should.
    thats what i thought too and like i said the bolts get tons of purchase on the fork so it all seems solid. it just looks a little flimsy and i am gonna have a sh!tload of fast downhills to do in the next two weeks. i might take the file to the adapter anyway and see if i can remove some material evenly enough to use it.

  11. #11
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    What you have going on is pretty sketchy IMPO. No way I'd embark on a 100 mile race in steep terrain that I've been training for all season with a front brake setup like that. You've got plenty of time to get the right adaptor before the race, DO IT.

  12. #12
    rebmem rbtm
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    The washer stacks are basically doing the same thing that Avid's post mount spacers do.




  13. #13
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    Quote Originally Posted by customfab View Post
    What you have going on is pretty sketchy IMPO. No way I'd embark on a 100 mile race in steep terrain that I've been training for all season with a front brake setup like that. You've got plenty of time to get the right adaptor before the race, DO IT.
    its actually 240 miles (over 6 days) haha. i have 5 days to find a better solution but if a shimano 180mm adapter doesnt work for a shimano 180mm rotor than i am not sure another off the shelf solution exists. i am still trying to wrap my head around why this adapter doesnt work cause it should be simple.


    Quote Originally Posted by cobba View Post
    The washer stacks are basically doing the same thing that Avid's 180mm post mount spacers do.
    i saw that pic after some of the discussion here and i agree that my washers are basically same.

  14. #14
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    Quote Originally Posted by cobba View Post
    The washer stacks are basically doing the same thing that Avid's post mount spacers do.
    Basically is not the same. The difference is that washer can move against each other and allow the bolt to flex a lot more than a solid spacer will. Over time it could sheer the bolt. Not sure how long that would take or even if it'll happen. Fact of the matter is you DO NOT hack brake setups together. They need to be setup correctly end of story.

  15. #15
    rebmem rbtm
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    I don't think there's an issue, prove me wrong.

  16. #16
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    Customfab is right - don't use hack washer stacks. The correct, SOLID adapter prevents potential shearing of the bolts, due to braking forces. A washer stack will allow each bolted end of the caliper to move independently...and that is where all the trouble starts.
    "The mind will quit....well before the body does"

  17. #17
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    Re: Is using washers instead of a brake adapter an issue?

    Agree with Zach and custom fab here - a stack of washers provides virtually no shear resistance, those avid spacers will give slightly more, but the best is a true adapter with two columns joined by a bar to make a solid box construction across both bolts.

    Those avid spacers always looked iffy to me as it is, washers are a step down from that. Due to the angle of the caliper, you can see the force from braking is diagonal to the washer stack so there is a strong shear force at play here.

    We've had this thread before, and folks have pointed out that sport bikes employ washers under the caliper too, but without actually doing the engineering calcs for that particular combination of dynamic forces, column height (washer height), bolt size and bolt shear strength, its impossible to make comparisons. If those sport bike designers spec'd it, you can bet they did those calcs with factor of safety 2 as usual. Can't say the same here.

  18. #18
    rebmem rbtm
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    Quote Originally Posted by Zachariah View Post
    The correct, SOLID adapter prevents potential shearing of the bolts, due to braking forces. A washer stack will allow each bolted end of the caliper to move independently...and that is where all the trouble starts.
    There's two bolts attaching the caliper so they can't move independently, if one bolt moves then the other bolt would also have to move.
    The two bolts would have to shear simultaneously, the front brake would of been locked up and you'd be flying over the handlebar before that'd ever happen.
    I'd say there'd be a better chance of stripping the threads in the post mounts or busting off the post mounts or breaking the brake caliper before the two bolts would shear.

  19. #19
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    Definitely more stress on the bolts using washers like that.

  20. #20
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    Quote Originally Posted by cobba View Post
    I don't think there's an issue, prove me wrong.
    Why take the chance in the first place?

  21. #21
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    Quote Originally Posted by cobba View Post
    The washer stacks are basically doing the same thing that Avid's post mount spacers do.



    I didn't realize that Avid, or anyone else, made individual spacers for each bolt rather than the standard solid adapter. It's still true that that set up definitely puts more stress on the bolt, but I doubt Avid would offer it unless they were quite certain that the stresses were far below what the bolt could handle.

    The washer stack doesn't seem too much different than those Avid spacers.

    Avid Post Mount Disc Adapter Kit 180 Front / 160 Rear

  22. #22
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    Quote Originally Posted by Zachariah View Post
    Customfab is right - don't use hack washer stacks. The correct, SOLID adapter prevents potential shearing of the bolts, due to braking forces. A washer stack will allow each bolted end of the caliper to move independently...and that is where all the trouble starts.
    This^^^

    Will you have a problem????? maybe maybe not. Do you want to take the chance? If you bust a bolt, your caliper will probably go into your wheel. So, bad things happen then.

    Personally, I think that whole CPS stack washer thing is the major contributing factor to the dredded "Turkey Gobble" that so many experience.
    Lead by my Lefty............... right down the trail, no brakes.

  23. #23
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    Quote Originally Posted by smilinsteve View Post
    I didn't realize that Avid, or anyone else, made individual spacers for each bolt rather than the standard solid adapter. It's still true that that set up definitely puts more stress on the bolt, but I doubt Avid would offer it unless they were quite certain that the stresses were far below what the bolt could handle.

    The washer stack doesn't seem too much different than those Avid spacers.

    Avid Post Mount Disc Adapter Kit 180 Front / 160 Rear
    I knew Avid did this, but they still have those CPS washers. I still think this puts a big stress on those bolts. Maybe the have a higher grade bolt, but doubt it.

    Avid is not know for having great set ups. The Avid turkey gobble still present today, (I heard it this past Saturday) and will live in infamy (sp?)
    Lead by my Lefty............... right down the trail, no brakes.

  24. #24
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    Quote Originally Posted by ziscwg View Post
    Will you have a problem????? maybe maybe not. Do you want to take the chance?...
    dont worry i wont be taking chances. i threw it out there and lots of people have weighed in which helps. i am gonna try and source an adapter that will work or try and remove a few mm of material from the one i have. i was nervous enough about the washer stacks to post here in the first place and you guys confirmed my suspicions. i have a 160mm rotor i can always throw on as well with no adapter needed.

  25. #25
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    Quote Originally Posted by ziscwg View Post
    I still think this puts a big stress on those bolts. Maybe the have a higher grade bolt, but doubt it.
    I also wondered if they might use a higher grade bolt. I also doubt it.

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