Thruxton Thruxton R Gear Linkage Bolt Failure

Discussion in 'Thruxton, Scrambler & Trident' started by timboo, Oct 14, 2022.

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  1. timboo

    timboo Senior Member

    Oct 17, 2021
    289
    113
    Cambridgeshire
    #1 timboo, Oct 14, 2022
    Last edited: Oct 15, 2022
    https://www.thetriumphforum.com/thr...ew-like-blood-from-a-stone.36037/#post-600965

    Having fought with the dealer about the above link.

    I finally got to take my recently repaired Thruxton R out to try and bed it in.
    A little 43 miles later my gear lever linkage has suddenly failed.
    I thought there was a recall for something similar to this unless I’m losing my mind.

    The actual bolt has snapped god knows how.
    I will investigate next week

    Was it caused by the recent repair or service?
    Was it caused by overtightening as part of a recall?
    Was it caused in transit?
    Had it slowly worked loose and snapped?

    I need to understand what the recall and repair entailed

    I am lucky to not have come off today.

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  2. Wessa

    Wessa Cruising

    Apr 27, 2016
    11,355
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    I had exactly the same problem on my Speed Twin and Thruxton R. Both were fixed Under warranty. In my opinion there is/was a problem with the linkage on both bikes.
     
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  3. timboo

    timboo Senior Member

    Oct 17, 2021
    289
    113
    Cambridgeshire
    #3 timboo, Oct 15, 2022
    Last edited: Oct 15, 2022
    Right

    Done some research this morning firstly tracking down which parts I need. When I looked at the image as attached the bolt, which has snapped doesn’t feature.
    Following a call with my local dealer they advise bolt comes pre fabricated onto the gear lever.

    I will dismantle it at some point today to see if there are any obvious marks, If I’m honest I’d much prefer to find something pointing to an impact as I’m losing the will to live at the moment.
     
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  4. timboo

    timboo Senior Member

    Oct 17, 2021
    289
    113
    Cambridgeshire
    #4 timboo, Oct 15, 2022
    Last edited: Oct 15, 2022
    Thanks for posting. Was it the actual bolt breaking? In your opinion what caused it?
     
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  5. Ducatitotriumph

    Ducatitotriumph Crème de la Crème

    Apr 25, 2019
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    #5 Ducatitotriumph, Oct 15, 2022
    Last edited: Oct 15, 2022
    I think I know what MIGHT have happened?
    I've had this bolt/joint come dangerously close to coming out on my speed rs (the gear changes were terrible) and I removed mine, added loctite and its been fine since.
    I think good 'ole blade have tightened it up and actually stripped the thread?
    You can replace just that part as behind the black rubber cover, there's a little circlip and if you remove it, you can remove the broken bolt/joint.
     
  6. timboo

    timboo Senior Member

    Oct 17, 2021
    289
    113
    Cambridgeshire
    Cheers. You have to buy the entire assembly from triumph.
    I still have part of the bolt within the gear lever also.
    I’m trying to see if there was a recall relating to the gear linkage. Seem to remember something as part of my research pre purchase but to the life of me I can’t find it now.
     
  7. timboo

    timboo Senior Member

    Oct 17, 2021
    289
    113
    Cambridgeshire
    #7 timboo, Oct 15, 2022
    Last edited: Oct 15, 2022
    Here is a pic showing the original spacing between the balljoint and lever before it broke. Would someone mind looking at their bike to see if theirs has a similar spacing please.

    Since removing the lever I have also noticed the inside of the lever is damaged. You couldn’t see this from the outside of the bike. I can’t say when that has happened certainly nothing I have done since owning the bike. You would have thought any stress would have been applied to the main bolt holding the lever on opposed to the linkage.

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  8. timboo

    timboo Senior Member

    Oct 17, 2021
    289
    113
    Cambridgeshire
    I’m really keen for someone to share an image of their gear lever where the end of the ball joint meets it in the first image
    See these 2 images the front connection is flush where as there was a significant gap at the lever

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  9. Iron

    Iron Elite Member

    Dec 29, 2021
    2,575
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    Sorry, haven't got one of those but here's a chap that's made up his own QS and linkage. You can see that the levers are from a Thruxton.
    The rose joints/ball joint/rod ends should be bolted up tight. I've used these types of joints on forward/rear controls on custom builds and you wouldn't want them loose. If there was an issue with needing the rod a bit further out then I'd bend the rod or put a spacer in there. No way would I just leave the bolt half hanging out.

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    I'm so worried about these joints coming loose that I fit with a longer bolt through the threaded rose and lock off with a locktighted nut. No idea if you have the room but I always figure it out to give me peace of mind.
     
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  10. timboo

    timboo Senior Member

    Oct 17, 2021
    289
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    Cambridgeshire
    #10 timboo, Oct 15, 2022
    Last edited: Oct 16, 2022
    I wasn’t trying to jump to conclusions but your image sums up what I am currently thinking that both joints would look the same. looking at the thread inside the lever there is no lock tight residue or marking.
    When I pickup the new part I will immediately know whether I am barking up the wrong tree or not. I also plan to examine bikes in the show room
     
  11. Wessa

    Wessa Cruising

    Apr 27, 2016
    11,355
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    North West England
    Yes it was the bolt that sheared. In my opinion it is a design/manufacturing fault. Touch wood I’ve not had no further problems.
     
  12. timboo

    timboo Senior Member

    Oct 17, 2021
    289
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    Cambridgeshire
    Did yours have the gap like mine?
     
  13. timboo

    timboo Senior Member

    Oct 17, 2021
    289
    113
    Cambridgeshire
    #14 timboo, Oct 15, 2022
    Last edited: Oct 15, 2022
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  14. timboo

    timboo Senior Member

    Oct 17, 2021
    289
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  15. Baza

    Baza Elite Member

    Jul 25, 2020
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    The hex nut on the ball/threaded shaft should be snugged up to the lever/arm of the gear lever or gearbox arm. This then means that any bending moments exerted by operating the gear lever are borne by the ball to hex nut section of the ball/threaded shaft whereas with the shaft loose, i.e. a gap between hex nut and lever/arm the bending moment is borne entirely by the threaded portion of the ball/threaded shaft. Hence snapped threaded section.

    A possibility that comes to mind is that every time a gear change is made there is rotational movement between link shaft and the gear lever or gearbox arm. Hence the need for such a joint between the two parts. I haven’t measured the change in angle between these two parts but would imagine it to be reasonably small, maybe 20° or so max.

    What if the friction between the ball and the socket it sits in differs with direction of rotation so that with every gear change the ball/threaded shaft is being gradually unscrewed from the gear lever or gearbox arm. Maybe not by the entire rotational movement each time, could be a localised tight spot. This could also differ between up and down changes depending upon whether the ball is pushing or pulling the link rod.

    The thread that has snapped is an M6 thread with a pitch of 1mm and from Tim’s photo I’m guessing that the ball/threaded shaft has backed out by some 5mm or so before it snapped. You only have to do some quick calcs to see that, that could amount to a goodly number of gear changes.
     
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  16. timboo

    timboo Senior Member

    Oct 17, 2021
    289
    113
    Cambridgeshire
    #17 timboo, Oct 15, 2022
    Last edited: Oct 16, 2022
    There is a whole host of lock tight at the end where it snapped off. At the opposite end where you can also see the thread inside the lever there is no sign suggesting that the bolt has moved at all. I recon it has been in that position for a good while and as you quite rightly say it wouldn’t have been as strong and hence it breaking.
    begs the question of how it has been missed during service couple of weeks ago Its only through my own research I now know what to look out for but I’d expect a mechanic to spot it a mile off.
     
  17. Iron

    Iron Elite Member

    Dec 29, 2021
    2,575
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    There's a pretty heavy scrape on the lever, maybe that damage warranted a bit of work by the PO. Does it look like it's been crossthreaded? If it's been threaded then whoever ballsed it up would know that continuing to screw it in wouldn't allow any hold at all. Maybe the PO then thought to locktight it and hope it held until it was taken as part exchange.
     
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  18. SpeedTwin1200

    SpeedTwin1200 Senior Member

    Jul 21, 2019
    261
    113
    Hampshire
    I remember when I sorted mine out, that I had to find a thin spanner to tighten that nut as a standard spanner was too thick and got trapped before the bolt was all the way in. Maybe that's why yours wasn't screwed in enough?

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  19. timboo

    timboo Senior Member

    Oct 17, 2021
    289
    113
    Cambridgeshire
    #20 timboo, Oct 15, 2022
    Last edited: Oct 15, 2022
    Many thanks I’m going to do a similar thing and mark it up once it is fixed.
    I’ve just gone through some photos and can clearly see that the bolt has moved since February.
    Would it ever be removed during a service to clean and re grease the ball joints?

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