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Shock bushes - DU/DP/polymer?

Discussion in 'Downhill & Freeride' started by - seb, Mar 12, 2008.

  1. - seb

    - seb Turbo Monkey

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    I've never replaced a bush before, I just ignore them and get them done when I get my shock serviced. I'm feeling a bit cheap at the moment, and my shock appears to be working fine, so I might skip the service and just install a bush myself.

    http://www.tftunedshox.com/mount_kits.htm

    I know I need 22mmx8mmx12.7mm, so I have the option of three different coatings on the bush - DU, DP or polymer. I can't see anywhere that explains the differences. I'll ask them the same question when I call to order it tomorrow, but for now I thought I'd ask the 'monkeys.

    I'm probably going to go for the "heavy duty" kit unless anyone can tell me a reason not to?

    PS I'm I stupid to not get my shock serviced? I'm reluctant to spend that sort of money (£75, a quarter the cost of a new DHX5) when I think it's working fine at the moment?
     

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  2. buildyourown

    buildyourown Turbo Monkey

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    The DHX seems to be a very durable shock. I haven't personally seen one blow up. On newer, low leverage bikes, shocks don't have to work as hard as they used too. Especially if you're light and running a 400# spring.
    Every 2-3 seasons seems like a reasonable service interval if things are working well. I replace my DU bushings several times a year.

    The mount kit that TF shows are very different. The standard kit will last only a couple runs on some bikes. The heavy duty kit is what you want.
     
  3. - seb

    - seb Turbo Monkey

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    Yeah I know I want the HD one, it's the bush type that I'm clueless about :)

    As for low leverage, my DHi only has a 2.5" stroke, and (I'm guessing) 8" of travel, so that's fairly high leverage really isn't it (I think anything over 3:1 is considered high?)
     
  4. djamgils

    djamgils Monkey

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    I would go with the polymer bushes. When the DU of DP bushes are worn out you will get a metal to metal contact and you will start wearing out your mount kit. When you have a polymer bushing you will never get a metal to metal contact so you wont have to replace the mount kit.
    thats my philosephy, correct me if I am wrong.
     
  5. - seb

    - seb Turbo Monkey

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    Yeah, is what they said too :)
     
  6. mushik

    mushik Chimp

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    what tool are you using to take the old bushes out with?
     
  7. - seb

    - seb Turbo Monkey

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  8. Jeremy R

    Jeremy R <b>x</b>

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    behind you with a snap pop
    Just so you know, my dumb ass ordered those polymer bushings one time. Got raped on the shipping, and then found out they wear out faster than the regular metal ones. I was hoping they would last longer so I would not have to change the bushings so much on my DHR.
    Ah, but once I got a Double Barrel, I have not changed a bushing in two and half years. I use to change them every two months.
     
  9. djamgils

    djamgils Monkey

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    lets presume the coating material wears just as fast as the polymer. the reason why the polymer bushing seems to wear faster is because you never get a metal to metal contact. My guess is that with the du bushing you wear out the coating in a short while so you then have metal to metal without play. Then when the metal to metal connection starts having play it ruined your mounting hardware. so you have to replace the mounting hardware and the du bushing.
    With the polymer bushing the wear will be the same rate untill you get play. But at that point you only need to replace the bushing.
     
  10. - seb

    - seb Turbo Monkey

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    I think djamgils got it in one :)

    Next question: should I grease bushings, or fit them dry?
     
  11. davep

    davep Turbo Monkey

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    Dry.

    They are designed to be self lubing. You can use something, but it will only serve to attract dust that will then act like an abrasive.
     
  12. Spunger

    Spunger Git yer dumb questions here

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    There is a trick tool for this if you must change them out all the time, this makes it go very quickly. It's a tool made by a company named CTS. It's their bushing removal/install tool. About $30 I think?

    I know the ones that came stock on my 5th element sucked. Maybe 5-10 rides out of them and the lower one would be loose already. I was told to use the Fox ones, with the reddish coating on the inside. I have since changed to those and have yet to replace them. I'm also using the heavy duty bolts and hardware.

    What looked trick was the BOS rear shocks with mini-needle bearings. that's what should be in there anyways.
     
  13. - seb

    - seb Turbo Monkey

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    Hmm, I don't think you get enough rotation and the shock loads are too high for it to be a suitable bearing placement. I presume BOS have done their homework though... :)