Bearing holder clamp bolt

Discussion in 'Mechanics Garage' started by John White, Aug 16, 2018.

  1. John White

    John White New Member

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    Hi all, just changed the chain and sprockets on a 91 750fm single sided swing arm. The bolt is pretty rock solid and I'm not convinced that it's going to hold the chain tight. I managed to loosen it enough to adjust the chain. Any ideas please what my problem is please? (apart from being a useless mechanic)
     
  2. squirrelman

    squirrelman Member

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    Torqued to proppa spec on the bolt, the chain tension won't change, so don't fret. :Heh:
     
  3. John White

    John White New Member

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    Thanks for the reply, fingers crossed.
     
  4. John White

    John White New Member

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    Popped out for a ride, 4 miles down the road and the chain was slack again. The clamp bolt torqued well over the recommended value. frettting now. any ideas anyone?
     
  5. squirrelman

    squirrelman Member

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    I've been on this (and the other) forum for about 18 years, and i never heard of that problem before..............:(

    How much of a gap is there between the sections that the bolt secures when the bolt is tight ??

    And this never happened before the chain replacement ?
     
  6. John White

    John White New Member

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  7. John White

    John White New Member

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    Thanks. I only recently got the bike and the problem occurred on the first ride. I changed the cogs and chain as aided that it may be seized in places. Í will check the gap in the morning as it's nearly midnight here. Thanks again
     
  8. squirrelman

    squirrelman Member

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    So possibly the PO damaged the bolt hole threads and you're not getting the clamping force you need.
     
    Last edited: Aug 18, 2018
  9. NorcalBoy

    NorcalBoy Member

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    What I suspect is happening is that the bolts have actually been stretched from years of being tightened (at times, probably incorrectly) during the torquing process....which is basically what torquing is, physically stretching the bolt. At some point, the bolt is going to reach the point where it is stretching the bolt and fatiguing the threads . Try replacing the bolts themselves with some decent quality replacements. It's a cheap way to eliminate a potential reason. I would do that anyway, it's kind of an important interface.
     
  10. John White

    John White New Member

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    I managed to get the bolt out after much effort, it's pretty shot, thread knackered. I'll get another and let you know how I get on. Thanks all
     
  11. Terry Smith

    Terry Smith Member

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    I recall reading that if you don't have the standard washer/brake-hose guide installed , then the bolt can bottom out in the threaded hole in the swingarm, and you don't get full clamping force at the bearing holder.
     
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  12. John White

    John White New Member

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    Thanks all. It seems that these bolts are difficult to get in the uk, so I've got hold of a bolt that that is a wee bit longer and has a smaller diameter and put a nut on and tightened it to the proper torque. Fingers crossed this has worked so far. Thanks all again.
     
  13. Terry Smith

    Terry Smith Member

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    The original bolt 90155-MBG-000 is used on all the VFR800 models up to the current one, so it should be easy to get from a dealer.
     
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  14. John White

    John White New Member

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    Hi, Just checked both the 750 and 800 parts schematics and it looks like the bolts are diffrent sizes, the 750 shows 14 x 53, while the 800 shows 16 x 51. Different parts numbers too ??
     
  15. Terry Smith

    Terry Smith Member

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    Sorry John, for some reason I thought you had an 800, not the 91 750. You are correct, the 750 uses a different part number
    90155-MT4-000 and it is listed as unavailable.
     
  16. John White

    John White New Member

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    NO worries , thanks for taking the trouble to reply
     
  17. NorcalBoy

    NorcalBoy Member

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    Measure the bolt diameter, overall length, thread length, and thread pitch. Go over to ProBolt and order a couple new ones. They are right in your backyard. You can get them in ti and stainless. They also sell the ti ones at Mettec here in the USA. I replaced them on my 800 and I don't think the bolt has changed for a very long time, if ever.
     
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  18. John White

    John White New Member

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    Thanks I'll give them a try
     
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