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  1. #1
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    Hollowtech II Crank install question

    Yesterday after work, I installed a Hollowtech 2 crankset (9sp XT 770). First time for a Hollowtech 2. It replaced my old Octalink XT 752 crankset. The whole process went smoothly with a little help from the rubber mallet. Not knowing how far in I should go I ended up with the right side rubbing the bearing so I tapped it out a little bit-a couple of/three millimeters, installed the left arm and finished up.

    Cranks spun beautifully, shifting was fine. I did have to adjust the barral on my front shifter. About a turn and a half out. So I think the chain line is a bit different. Seems to be the case as I perused some older threads on this site.

    So my question is how do you know or tell if the crank is correctly centered?

  2. #2
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    The bottom bracket should have 3 spacers for the hollow tech cranks. Typically one spacer goes on the non-drive side (between the bearing and crank arms) and two go on the drive side. Crank should not be touching the bearing, I suspect your chainline might be off.

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    It should be against the bearing on both sides - no room to move or center.
    When I install a Hollowtech crank, I push the drive side in till it bottoms out - a brand new BB may require a rubber mallet. Then put the left crank arm on, install the plastic center bolt/nut and tighten it as tight as I can get it with my fingers. Then back it out and re-tighten it just snug. Give the cranks a good spin. Push the little stopper plate in and then alternately tighten the left crank arm bolts to the correct torque.
    A brand new BB will feel tight but after a bit of use it will be OK.

  4. #4
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    Quote Originally Posted by Slash5 View Post
    It should be against the bearing on both sides - no room to move or center.
    When I install a Hollowtech crank, I push the drive side in till it bottoms out - a brand new BB may require a rubber mallet. Then put the left crank arm on, install the plastic center bolt/nut and tighten it as tight as I can get it with my fingers. Then back it out and re-tighten it just snug. Give the cranks a good spin. Push the little stopper plate in and then alternately tighten the left crank arm bolts to the correct torque.
    A brand new BB will feel tight but after a bit of use it will be OK.
    good advice.. make sure you back out and then just lightly snug the little plastic cap...
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  5. #5
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    Not trying to qustion Slash's knowledge but the spacers I mentioned are straight from the Shimano installation PDF. Unless you are running something other than a 68mm BB and/or an E-type der.hanger then you should be using 3 spacers, one on the non-drive and two on the drive side. The spacers came with my BB when I bought it along with my 9 sp SLX crankset.

  6. #6
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    Quote Originally Posted by robc in wi View Post
    Not trying to qustion Slash's knowledge but the spacers I mentioned are straight from the Shimano installation PDF. Unless you are running something other than a 68mm BB and/or an E-type der.hanger then you should be using 3 spacers, one on the non-drive and two on the drive side. The spacers came with my BB when I bought it along with my 9 sp SLX crankset.
    ahhh he didn't say anything about the spacers...
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  7. #7
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    Quote Originally Posted by robc in wi View Post
    Not trying to qustion Slash's knowledge but the spacers I mentioned are straight from the Shimano installation PDF. Unless you are running something other than a 68mm BB and/or an E-type der.hanger then you should be using 3 spacers, one on the non-drive and two on the drive side. The spacers came with my BB when I bought it along with my 9 sp SLX crankset.
    Well I have a 68mm BB and use a band type FD. The instructions say to use 2 spacers on the drive side and one on the other, which I did. (if the E-type Shimano says to use one spacer on each side). That was not the problem. See below.

    Quote Originally Posted by Slash5 View Post
    It should be against the bearing on both sides - no room to move or center.
    When I install a Hollowtech crank, I push the drive side in till it bottoms out - a brand new BB may require a rubber mallet. Then put the left crank arm on, install the plastic center bolt/nut and tighten it as tight as I can get it with my fingers. Then back it out and re-tighten it just snug. Give the cranks a good spin. Push the little stopper plate in and then alternately tighten the left crank arm bolts to the correct torque.
    A brand new BB will feel tight but after a bit of use it will be OK.
    Did that...

    Based on your advice, I undid the nondrive stuff, tapped in the right side stuff a mm or two with my trusty mallet and put everything back together and lightly snugged down the plastic cap. Now all is well in the world!

    Thanks!

  8. #8
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    Quote Originally Posted by Mr5150 View Post
    .....

    Based on your advice, I undid the nondrive stuff, tapped in the right side stuff a mm or two with my trusty mallet and put everything back together and lightly snugged down the plastic cap. Now all is well in the world!

    Thanks!
    just make sure you tighten the 2 clamp bolts too
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  9. #9
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    Quote Originally Posted by thomllama View Post
    just make sure you tighten the 2 clamp bolts too
    That would explain why the left crank arm fell off!

    (in case the smiles don't get thru bolts tightened to 110 inch pounds per my torque wrench)

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