Featured Thruxton ‘r’. Beware! Front Wheel Fitment

Discussion in 'Thruxton, Scrambler & Trident' started by Ken walburn, Jun 23, 2019.

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  1. Ken walburn

    Ken walburn Noble Member

    Jun 28, 2017
    944
    300
    Essex
    Just had two new tyres fitted to loose wheels on my bike. I re fitted the rear wheel without any issues. However, the front wheel fitment, different story. Spacers fitted inside oil seals, wheel offered up, spindle fitted & tightened to correct torque. Spindle clamp bolts tightened to correct torque, callipers fitted, bolts tightened to correct torque. Job done! Oh no, rotated wheel, right hand calliper rubbing hard against brake disc on the outer face. On inspection, calliper not mounted square. WTF? Stripped & re fitted on three occasions until I realised that once you have tightened spindle, you need to fit callipers & then pull the right hand fork leg away from the disc in order to centralise the calliper & then torque up the spindle clamps. At first I had the end of the spindle flush with the outside of the fork leg coz that’s what the fork leg wanted to do.
    So moral of the story, take a f****** picture of everything before you strip. The outer edge of the spindle needs to be in line with the inner machined part of the right hand lower leg as per photo, otherwise right hand calliper does not align. A whole day of my life wasted!

    C134316D-891D-44B5-9510-BCE81DC70309.jpeg
     
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  2. Glyn Phillips

    Glyn Phillips Old’N’Slow
    Subscriber

    Jun 21, 2018
    1,158
    750
    Essex
    If you leave the pinch bolts until last that clamp the spindle,they all come into alignment
     
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  3. Ken walburn

    Ken walburn Noble Member

    Jun 28, 2017
    944
    300
    Essex
    Now you see for some reason mine didn’t. I literally had to lever the forkleg away from the centre of the wheel before tightening spindle clamps, in order to align the calliper. Really weird.
     
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  4. Glyn Phillips

    Glyn Phillips Old’N’Slow
    Subscriber

    Jun 21, 2018
    1,158
    750
    Essex
    Refit wheel with spindle hand tight, refit calipers and torque up, tourque wheel spindle, torque pinchbolts. Good to go
     
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  5. Ken walburn

    Ken walburn Noble Member

    Jun 28, 2017
    944
    300
    Essex
    Mmmmm? Now it’s all good to go, I’m not fiddling with it again TIL it needs new tyres. A lesson learnt
     
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  6. Allan seggie

    Allan seggie New Member

    Sep 22, 2019
    0
    1
    Scotland
    Hi Ken glad I have found someone with the same issue
    as me, likewise I carried out same procedure as you and after a weekend away got home to discover the disc scoring the inner of caliper. Luckily I it has not damaged disc or caliper. I think this is a shitty design as normally you would expect the spacer to be hard up against fork leg ,not with a gap of approx 4mm .
    What are your thoughts on this
    Allan
     
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  7. Ken walburn

    Ken walburn Noble Member

    Jun 28, 2017
    944
    300
    Essex
    Hopefully my post will save peeps time & money. Agreed, you should not have to pull the right fork leg out from it’s natural hanging position. I was worried about potential issues with the fork seal, but have done loads of miles since without cause for concern. Every day is a school day
     
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  8. Allan seggie

    Allan seggie New Member

    Sep 22, 2019
    0
    1
    Scotland
    exactly Ken I was concerned about the fork seals as well but good to hear that it is not a concern.
    cheers Allan
     
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  9. JULIAN WW

    JULIAN WW Well-Known Member

    Nov 27, 2019
    106
    83
    carlton in lindrick
    I have exactly the same issue and my local dealer did as you and moved the bottom of the right hand fork leg out before reclamping to the spindle (wheel axle) This did not completely centralise the caliper in relation to the disc but created enough clearance to prevent metal to metal contact. As an engineer I am not impressed by this poor tolerencing but my big concern is that we now have a 3 mm gap between spacer and fork so the wheel is no longer "fixed" relative to the axle! ONLY the brake pads are preventing the wheel moving from side to side. I would be very pleased if someone can provide the error in my logic?
     
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  10. Callumity

    Callumity Elite Member

    Feb 25, 2017
    3,037
    750
    Nr Biggar
    I was taught years ago to finger tighten the axle pinch bolts and apply the front brake and bounce the suspension 3 or 4 times to align everything then torque up (even more vigorously if the triple trees/yokes had been fiddled with and also needed aligning.)
     
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  11. JULIAN WW

    JULIAN WW Well-Known Member

    Nov 27, 2019
    106
    83
    carlton in lindrick
    Sound practice .so imagine you have done just that and you find your left brake disc is running in the centre of the corresponding caliper whilst the right is scraping on its disc, that is the caliper itself not just the pads, because the brake disc is not in the middle of the casting. No scope to move the caliper on its mounting screws and the disc is "floating" correctly. Lever the fork leg out?
     
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  12. JULIAN WW

    JULIAN WW Well-Known Member

    Nov 27, 2019
    106
    83
    carlton in lindrick
    Sound practice .so imagine you have done just that and you find your left brake disc is running in the centre of the corresponding caliper whilst the right is scraping on its disc, that is the caliper itself not just the pads, because the brake disc is not in the middle of the casting. No scope to move the caliper on its mounting screws and the disc is "floating" correctly. Lever the fork leg out?
     
  13. Callumity

    Callumity Elite Member

    Feb 25, 2017
    3,037
    750
    Nr Biggar
    In that event I would first check that the fork legs were parallel. Tightening the pinch bolts before the axle bolt will ensure they won’t be!
     
  14. Eldon

    Eldon Elite Member

    Nov 14, 2018
    1,515
    750
    North Yorkshire
    Can you provide two pictures for better further advice,
    Picture 1 showing the 3mm gap
    Picture 2 showing the spindle on its own.

    Depending on the design, if a stepped spindle is employed then there will not be a gap. Im pretty certain that lateral wheel position will not be dictated by the brake pads as you suggest.
     
  15. Ken walburn

    Ken walburn Noble Member

    Jun 28, 2017
    944
    300
    Essex
    Hi Julian. The only way on the Thruxton R is to tighten the front spindle, lever the right hand fork leg away from the centre of the hub allowing. 3 to 4 mm recessed gap as per photo at top of thread. This will give you the clearance you need between the disc & the calliper. Then torque up the pinch bolts to keep in desired position. Awful design, but hey, there you go.
     
  16. JULIAN WW

    JULIAN WW Well-Known Member

    Nov 27, 2019
    106
    83
    carlton in lindrick
    Firstly thanks to Ken for the original post & thread and also to all who replied to me. So this morning I satisfied myself that the stepped diameter wheel spindle means the right hand wheel spacer is held tight to the hub whilst the left hand spacer is clamped between the left fork and the wheel hub. The wheel cannot move out of position with the spindle tightened up, irrespective of the clamping of the RH fork leg to the wheel spindle. At this stage, on my bike, the left hand caliper is correctly positioned (central) to its brake disk. In order to position the right hand caliper satisfactorily, relative to its disc, the right hand fork must be moved along the wheel spindle which, for this bike, meant a 2mm gap between the wheel spacer and fork to gain 0.3mm clearance between the caliper lugs and disc.(min clearance quoted in the Haynes manual) As Ken showed this corresponded to the head of the spindle aligning with the chamfer in the fork (see pics). The following is not a recommendation that anyone should implement unless they are satisfied it is safe & advantageous - your decision. Not liking the appearance of the gap between the RH fork and the wheel spacer, to avoid use of any lever and to fix the dimensions to simplify future assembly, I used some suitable aluminium washers from my shed stock as shims (see pics). I needed two of these to get the correct dimension but I will replace these with a single 2mm thick version when I've made it. Note the hex head clamping screws were yet to be re-fitted when I took the photos. Your call as to who is the worst bodger, me or Mr Triumph.

    Front wheel spindle.JPG

    RH Fork-Spindle Posn.JPG

    Spindle shim.JPG

    Spindle shims added.JPG
     
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  17. Dave Roxburgh

    Dave Roxburgh Well-Known Member

    Jul 5, 2019
    59
    68
    Suffolk
    Hey Ken,

    Could it be that the axle wasn't quite free to rotate in the RHS fork and so as the axle went in it dragged the fork in with it?

    I read your post before I did mine and so was super-cautious. As new, from the factory, my axle was inset 3.8mm inside the outer edge of the fork before I released the clamp bolts.

    I followed the procedure in the Haynes manual - ensured the clamp was not restricting movement of the axle AT ALL (i.e. not even finger tight), torqued up the axle, pumped the forks up and down and torqued up the clamp bolts. I measured the the inset and again, it had naturally settled back to 3.8mm.

    I don't believe the factory would have been levering the fork leg around to get it to fit when they assembled the bike.

    If your fork is deflected inboard then I would guess that either the fork has a defect... and I would get that checked. Or something's dragging it inboard as you tighten the axle up.

    If I recall correctly, someone said on here that it can't be right that there's a 'gap' between the RHS fork and the RHS spacer. It is OK - the axle itself compresses the [RHS spacer, bearings, wheel and LHS spacer] assembly against the LHS fork - so there's no way the wheel can wander around laterally. The RHS fork then clamps on the end of the axle head but that only provides a 'vertical' mounting - it doesn't need to play any part in compressing the wheel assembly.

    Good luck - hope you can get your fork leg to sit where it wants to... as that is (or should be) where it is straight.

    Dave
     
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  18. Kinjane

    Kinjane Active Member

    Oct 15, 2017
    79
    28
    Bristol, Land of Enger
    So what would happen if an undersized [on the width] front mudguard was removed from the equation prior to the commencement of the axle tightening sequence :eek:
     
  19. Mops

    Mops New Member

    Oct 15, 2019
    7
    3
    South Wales
    Is this video any use gents ?



    Regards
     
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  20. Paul Mac

    Paul Mac Member

    Apr 3, 2020
    38
    18
    Durham
    I would be seriously concerned if I had to lever a fork leg out to get the brake caliper to sit centrally .For one thing the forks will not be parallel anymore and will cause excessive friction /stiction , which could compromise the way the suspension acts . Something amiss somewhere I reckon
     
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