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02-06-23, 11:37 AM | #1 |
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Fuji nut
This is a Fuji nut:
Yamaha use them on the rear axle of all the 700s (MT-07/XSR700/R7 etc) and possibly the MT-09 range too. It acts like a Nyloc nut by way of that thin plate you can see at the top of the nut in the picture. I don't know why they use it although it is half the size of the axle nut on the SV and doesn't require any external locking but the SV has a plain nut and it isn't locked at all. Torque on both bikes are approximately the same at 105Nm (give or take). There is a problem. The nut is supposed to be reusable and it is - providing the nut hasn't been seated for a while and/or the thin metal plate hasn't got dirty, then it gets interesting because it unscrews about 2 turns and then seizes. If you keep turning it carefully mangles the thread on the axle which is £70 (Fowlers say it has to be ordered from Japan). I read about this soon after buying my XSR so I replaced it with a nut from Pro-Bolt but my friend with an MT-07 wasn't so lucky and needed a replacement axle when he replaced his chain (but found one at a breakers yard - £25). He's now bought a nut from Pro-Bolt too. The nut sits in a recess/chain alignment guide so you can't cut off a bad nut before it destroys your axle. Not one of Yamaha's better ideas imho.
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02-06-23, 11:53 AM | #2 |
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Re: Fuji nut
That seems crazy. So the nut on the SV is reusable? What's to stop it backing off?
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02-06-23, 12:49 PM | #3 |
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Re: Fuji nut
From the look of the axle nut on the Gen 3 bikes, it has a similar little locking plate but I've had the wheel out quite a few times with no issues ...
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04-06-23, 08:12 PM | #4 |
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Re: Fuji nut
I'm not sure this is universally correct.
Out of interest, I took a closer look at our bikes at the weekend (Wife's Pointy SK5 and son's recently acquired Curvy '99 X), and both have a nut like this on the rear swingarm. Maybe your previous SV had the standard nut swapped for a plain nut? I'm not sure something with no anti-loosening component is a wise idea in the relatively high-criticality environment of rear wheel axle. FWIW, my 1987 Yamaha FZ600 uses a castle nut and split pin, so perhaps this type of nut is a 'modern' phenomena that many manufacturers are moving to? (Having said that, I'll be bearing your story in mind and making sure to clean thoroughly before loosening for wheel removal, though I don't recall ever having had a problem in the past. Hopefully minor slackening for routine chain adjustment will remain trouble free.)
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Spannering the wife's SV650S K5 pointy in Black, and son's SV650 X curvy in Blue. RIP SV650 X curvy, crashed and written off December 2019. I'm (procrastinating about) fixing up an old Yamaha FZ600 to get myself fully back on the road. |
04-06-23, 08:43 PM | #5 |
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Re: Fuji nut
I looked at my SV rear axle more closely, it isn't a plain nut but neither is it a Fuji nut. I bought the bike new in 2016 and have had the axle out a few times with no issues. I haven't read about anyone having issues here or on the US forum, whereas you can find people with the issue on the XSR and MT-07/FZ-07 forums.
(Google fz07 axle seized)
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