Rear Axel And Bearing Marks

Discussion in 'Speed Triple' started by Linx, Dec 19, 2022.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. Linx

    Linx Well-Known Member

    Mar 14, 2020
    192
    93
    Stratford Upon Avon, UK
    At the weekend I decided to give the rear hub a clean and grease on my 2018 1050RS. Came apart fine but I noticed a lot of marking on the axel and on the sprocket carrier bearing. Looks like it's been picking up but as far as I can tell, that bearing doesn't spin. The sprocket carrier is a splined fit onto the axel. So they both turn together all the time. I don't actually see why it has a bearing and not just a spacer. Anyway have a look at the pics and give me your opinions on what's caused this and if I should replace the bearing. It is quite stiff to turn with fingers. Maybe just water ingress caused some rust??

    IMG_20221218_163625.jpg

    IMG_20221218_163454.jpg
     
  2. brown mouse

    brown mouse Elite Member

    Sep 15, 2018
    2,288
    943
    East Midlands, UK
    I've never looked at the construction of a single sided swingarm, but surely the axle doesn't rotate with the wheel? On 'normal' swingarms, the axle nut clamps the spacers and inner races of bearings into a rigid tubular sandwich between both sides of the swingarm, the wheel and sprocket carrier then rotate on their bearings.
     
    • Like Like x 1
  3. Pegscraper

    Pegscraper Elite Member

    Jun 12, 2020
    2,880
    800
    Yorkshire
    I assume the splines on the stub axle mate with the splines just below the bearing in the photo? If yes, then I can't see how that bearing does anything either. Even if the bearing is needed and does rotate somehow the inner race certainly should not spin on the axle. What goes on top of the bearing when it's fitted on the stub axle?
     
    • Creative Creative x 1
  4. Linx

    Linx Well-Known Member

    Mar 14, 2020
    192
    93
    Stratford Upon Avon, UK
    Below the bearing there is a spacer and then the splines. Above the bearing fits a seal and spacer, 2 washers and the nut that holds it all together.
     
  5. TRIPLE X

    TRIPLE X Well-Known Member

    Sep 1, 2021
    197
    93
    Downham Market, Norfolk
    The axle is fixed to the wheel so they spin together on the 2 bearings within the hub unlike a double sided swingarm where the wheel spins on the fixed axle. Never really thought about it but I assume the bearing in question is to accommodate movement in the cush drive ?
     
    • Like Like x 1
    • Useful Useful x 1
    • Agree Agree x 1
  6. Linx

    Linx Well-Known Member

    Mar 14, 2020
    192
    93
    Stratford Upon Avon, UK
    Ah right. Yes I guess that's it
     
  7. Pegscraper

    Pegscraper Elite Member

    Jun 12, 2020
    2,880
    800
    Yorkshire
    There must be something amiss there if the inner race is picking upon the axle. If the bearing doesn't rotate freely with no play I'd change it. The inner race should obviously be "locked" to the axle when the nut is tightened.
     
    • Agree Agree x 1
  8. Col_C

    Col_C I can't re...Member

    Aug 5, 2015
    1,425
    800
    Cornwall
    As @TRIPLE X rightly suggests this bearing only exists to allow the small movement required for the cush-drive to operate. As such the relative inner to outer race movement is only ever plus or minus a few degrees in its operating life. Difficult for me to comment without "hands on" but if the bearing feels smooth then it's probably just the rubber grease seal friction that you are feeling. As long as it feels smooth it's probably fine.
    The fretting marks could just be from the vibration and shock loads being transmitted from the chain/sprocket drive. It might be worth inspecting the cush rubbers and perhaps replacing if there's play when assembled.
     
  9. Col_C

    Col_C I can't re...Member

    Aug 5, 2015
    1,425
    800
    Cornwall
  10. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
    1,940
    1,000
    Lancashire
    The bearings are stiff to rotate and this is normal, the marks on the axle are due to Oscillation. Col Cs post outlines this perfectly, I have stripped and serviced a number of Triumphs with single sided swing arms (SSSA), and all have these marks, a lot comes into play with the SSSA, acceleration and braking are the two main factors, a lot of torque is transmitted to the rear hub and drive train, it is testament to modern materials and product quality that the components last as long as they do. Linx it is clear you look after your machine and take care with the maintenance, I would confidently say after re building the rear assembly you will get another 24 months trouble free before another strip and re grease, some early Triumph SSSA have more component parts, more often than not the needle roller bearing on these, collapses whilst removing the splined hub.
     
    • Like Like x 1
    • Agree Agree x 1
  11. Pegscraper

    Pegscraper Elite Member

    Jun 12, 2020
    2,880
    800
    Yorkshire
    If that's regarded as normal on these then I guess it's"OK".
    I just can't see how/why the inner race should move on the axle when the nut is torqued up. No way should the inner race of a bearing wear the shaft that supports it, that's the whole point of having a bearing. Ho hum.
     
    • Agree Agree x 2
  12. TRIPLE X

    TRIPLE X Well-Known Member

    Sep 1, 2021
    197
    93
    Downham Market, Norfolk
    Are they definitely witness marks? Mine had similar marks but they cleaned off easily with nothing more than WD40 and a cloth.
     
    • Agree Agree x 1
  13. Col_C

    Col_C I can't re...Member

    Aug 5, 2015
    1,425
    800
    Cornwall
    Fretting occurs on a microscopic level, if you look at the screen shot I posted you'll see that even the example shown appears to be a bearing inner race. Crevice corrosion and galling of stainless steel are other phenomenon that occur at this level. I'm not a motorcycle technician, but 30+ years as a mechanical design engineer, these things are not unusual.
     
    • Like Like x 2
    • Agree Agree x 1
  14. Linx

    Linx Well-Known Member

    Mar 14, 2020
    192
    93
    Stratford Upon Avon, UK
    Thanks guys. I will grease up, re-fit and not worry about it.
     
    • Like Like x 1
  15. Tom Swift

    Tom Swift Active Member

    Sep 24, 2021
    140
    43
    USA
    There's no good seal to prevent corrosion from occurring between inner races and axle. Grease needs to be applied between them all the way out to and including the threads to form a protective seal. You can see by the corrosion on the threads that it wasn't greased/sealed well.

    Standard swingarms are even worse because moisture can more easily make its way directly in thru the adjustment slots (rather than the more difficult path formed by the threads) and down the length of the axle if it isn't greased well.
     
Loading...

Share This Page