Author Rear Sprocket nut torque  (Read 8577 times)

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  • Offline PEMCBF

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    Offline PEMCBF

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    Rear Sprocket nut torque
    on: 30 December, 2015, 09:57:35 pm
    30 December, 2015, 09:57:35 pm
    The PDF manual I downloaded from a link on here is excellent - but the torque for the rear sprocket nuts states 108 Nm for the 5 x M12 nuts. That seems quite excessive - can anyone confirm this is correct?

  • Online Rev Ken   england

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    Re: Rear Sprocket nut torque
    Reply #1 on: 30 December, 2015, 11:15:18 pm
    30 December, 2015, 11:15:18 pm
    *Originally Posted by PEMCBF [+]
    The PDF manual I downloaded from a link on here is excellent - but the torque for the rear sprocket nuts states 108 Nm for the 5 x M12 nuts. That seems quite excessive - can anyone confirm this is correct?
    I too am a little surprised, but in my paper workshop manual for 2006-2008  CBF1000 A it says at 15-11 these nuts should be torqued to 108Nm. There is a photo of the rear sprocket with 'nuts' pointed out, so there is no room fro a misunderstanding.

    Unless of course someone knows differently......

  • Offline FireBladerDk   dk

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    Re: Rear Sprocket nut torque
    Reply #2 on: 31 December, 2015, 02:08:02 pm
    31 December, 2015, 02:08:02 pm
    In FireBladerDk's DIY article (which are always the best ;-) it says as follows:

    "Clean the threads and nuts for the rear sprocket and smear the threads with copper grease. Mount the new rear sprocket with the number of teeth visible and tighten the nuts in a criss-cross pattern to a torque which according to the Honda Shop Manual should be 108 Nm (11.0 kgfm, 80 lbfft). This figure is dry torque so having smeared with copper grease the torque should be decreased a little to say 90 Nm.
    The German repair handbook for CBF1000 from Bucheli Verlag AG however recommends further reduction to 70 Nm, as some Honda specialists claims there is a risc of pulling the mounting studs out of the hub.
    Whichever torque you decide to use, you should keep an eye on the nuts during the follwing period to ensure they do not get loose. Best is to put a dot of paint on the edge of each nut, so you can check that this 'seal' is not broken."

    Link: http://www.fireblader.dk/i_files/cbf1000chain/mc033.htm

    Happy New Year to all of you from ... Fireblader Fred  :041: :063:

  • Offline PEMCBF

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    Re: Rear Sprocket nut torque
    Reply #3 on: 31 December, 2015, 10:02:49 pm
    31 December, 2015, 10:02:49 pm
    Thanks for the info folks. There is no way i'm going to torque up to 108Nm when I eventually replace the rear sprocket especially if I replace the nuts with after market ones. I'll use similar lower torques to previous Honda bikes that I've owned (and they were higher powered super sports bikes).

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    Re: Rear Sprocket nut torque
    Reply #4 on: 31 December, 2015, 11:09:00 pm
    31 December, 2015, 11:09:00 pm
    I also think 108 Nm is quite excessive, but the manual must say 108nm for a reason. I would be tempted to get a spare sprocket bolt and nut, and torque it up (dry thread) in a vice and see what it can take before it strips the threads or shears.
    Maybe Robo can give some advice, he will have changed a few sprokets.

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    Re: Rear Sprocket nut torque
    Reply #5 on: 02 January, 2016, 10:40:08 am
    02 January, 2016, 10:40:08 am
    *Originally Posted by hondacbf [+]
    I also think 108 Nm is quite excessive, but the manual must say 108nm for a reason. I would be tempted to get a spare sprocket bolt and nut, and torque it up (dry thread) in a vice and see what it can take before it strips the threads or shears.
    Maybe Robo can give some advice, he will have changed a few sprokets.

    Yep changed loads and never used a torque wrench, it would be very strange is you lost a rear sprocket or if it came loose.

    only use a torque wrench on internal engine parts.

     :028:

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    Re: Rear Sprocket nut torque
    Reply #6 on: 02 January, 2016, 11:03:30 am
    02 January, 2016, 11:03:30 am
    *Originally Posted by Robo [+]
    Yep changed loads and never used a torque wrench, it would be very strange is you lost a rear sprocket or if it came loose.

    only use a torque wrench on internal engine parts.

     :028:
    I too rarely use a torque wrench as over the years I've learnt to 'feel' when a nut or bolt is tight enough. Admittedly on the way I've stripped a good number of threads and it takes a little time to learn the effects of different thread pitches and materials. Of course some modern applications demand an accurate torque where bolts are stretched past their elastic limit and can only be used once.

  • Offline FireBladerDk   dk

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    Re: Rear Sprocket nut torque
    Reply #7 on: 02 January, 2016, 12:31:46 pm
    02 January, 2016, 12:31:46 pm
    Sorry - but I tend to dissagree with you guis about not using a torque wrench, especially on safety critical nuts and bolts, and in particular if less experienced home-mechanics end up feeling they have to live up (down) to certain he-man behavior.

    The torque range between too low or too high moment is not very large if you consider all the things that may cause failure.

    Hence my recommendation on an open forum like this will have to be:

    1) If you are a home mechanic you must use a torque wrench on safety critical nuts and bolts, because you probably do not have a sufficiently good calibrated hand.
    2) If you are a professional mechanic, I'm sure your customers will want you to use a torque wrench, because it is their but which is going to sit on that bike when it fails.

     :oldie:  ....  :150: ... Fred



  • Offline jm2   england

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    Re: Rear Sprocket nut torque
    Reply #8 on: 02 January, 2016, 12:48:43 pm
    02 January, 2016, 12:48:43 pm
     :0461:

    But I too think 108 sounds rather high - I'd want to hold those screws/bolts in my hand to see if they were HT or something different that warranted such tightness.  I certainly wouldn't want them loosening off in motion.

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    Re: Rear Sprocket nut torque
    Reply #9 on: 02 January, 2016, 03:19:34 pm
    02 January, 2016, 03:19:34 pm
    A cheap or damaged torque wrench can do more damage than not using one.

     :028:

     



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