New reducers loose in shock bushing, new bushing time?- Mtbr.com
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  1. #1
    It's carbon dontcha know.
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    New reducers loose in shock bushing, new bushing time?

    I could feel some play coming from the shock, I'd got some new spare reducers in my parts and just removed the old ones. Uppermost reducers came out very easily, new ones are just as loose.

    I'm guessing this means the shock needs a new upper bushing?

    '07 Sultan.


    edit: Although bolted back up, the play doesn't seem to be there now. It was just the fact the old ones fell out and the new reducers dropped in, rather than pressed in.
    Last edited by 6thElement; 06-25-2011 at 12:56 PM.
    Rolling on 29", 650b, 8.3" and 23mm

  2. #2
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    Quote Originally Posted by 6thElement View Post
    I could feel some play coming from the shock, I'd got some new spare reducers in my parts and just removed the old ones. Uppermost reducers came out very easily, new ones are just as loose.

    I'm guessing this means the shock needs a new upper bushing?

    '07 Sultan.


    edit: Although bolted back up, the play doesn't seem to be there now. It was just the fact the old ones fell out and the new reducers dropped in, rather than pressed in.
    The new reducers will wear out faster w/ the old bushing .

  3. #3
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    needle bearings

    Mine were loose too, so I replaced them with needle bearings. The upper pivots the most so it wears quicker. I now have needle bearing on both the upper and lower ends of the shock. Buttery smooth now. Well worth the extra cost, there are many posts on these.

    http://www.enduroforkseals.com/id275.html

  4. #4
    The Bubble Wrap Hysteria
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    If your old reducers fell out then chances are the old reducers are good but you just need to replace the DU Bushings.

  5. #5
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    DU bushings have three layers. The lubricant, a brass wear layer and usually a steel case.

    The interface between the brass and the harder case is not smooth, if you wear your DU bush through this far it will chew up the reducers. The chewed up reducers then wear out the next DU bush in a short time-frame.

    On my bikes I run stainless steel shock pins with IGUS bushings. Best of all worlds, no maintenance, don't chew themselves apart, rotate very nicely, fantastic lifespan and can be toleranced to fit the variation in shock eyelets.

    The standard press-in reducers have so much friction they really kill small bump response. It's only bikes like the Stumpy FSR's which have no rotation that work well with them.
    Owner of www.shockcraft.co.nz, Mech Engineer, Tuner, Manitou, Motorex, Vorsprung EPTC, SKF, Enduro
    www.dougal.co.nz

  6. #6
    The Bubble Wrap Hysteria
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    Quote Originally Posted by Dougal View Post
    DU bushings have three layers. The lubricant, a brass wear layer and usually a steel case.

    The interface between the brass and the harder case is not smooth, if you wear your DU bush through this far it will chew up the reducers. The chewed up reducers then wear out the next DU bush in a short time-frame.

    On my bikes I run stainless steel shock pins with IGUS bushings. Best of all worlds, no maintenance, don't chew themselves apart, rotate very nicely, fantastic lifespan and can be toleranced to fit the variation in shock eyelets.

    The standard press-in reducers have so much friction they really kill small bump response. It's only bikes like the Stumpy FSR's which have no rotation that work well with them.
    I will agree with part of this statement. Why do engineers use DU Bushings in rotating equipment if they are so substandard. I designed a lubrication pump that saw shaft speeds upwards of 10K/rpm with DU Bushings.....and this pump was an aerospace application. I personally think the Fox hat style reducers is one of the biggest problems. I run the Rock Shox thru-axle type of reducers are have no problems.

  7. #7
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    Obviously there are many opinions on what is the best. Predictably, my opinion is that our needle bearing kits rule. Our only bump in the road was shock eyelet tolerance variations. That's now been dealt with. The 21.85, 22.20, & 39.98 kits all ship with "+" and "-" tolerance inner rings (other sizes will also include both inner ring tolerances within another week). We haven't had a single application of this new system that wasn't a great fit. Nothing is smoother. Guaranteed.

  8. #8
    mtbr member
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    Quote Originally Posted by mtnbiker4life View Post
    I will agree with part of this statement. Why do engineers use DU Bushings in rotating equipment if they are so substandard.
    They're not substandard at all, they just aren't ideal for the application. But the low cost means they will always be the default option.

    Quote Originally Posted by mtnbiker4life View Post
    I personally think the Fox hat style reducers is one of the biggest problems.
    Indeed. Press fit on rotating parts doesn't make much sense.
    Owner of www.shockcraft.co.nz, Mech Engineer, Tuner, Manitou, Motorex, Vorsprung EPTC, SKF, Enduro
    www.dougal.co.nz

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