Front sprocket nut :(

[Lawrence]

Its fallen off and disappeared, shaft looks a bit chewed up   waiting for RAC now to get me home.  Whatre me bst options? I'd prefer not to have to replace engine/box, is it possible to just weld the fecker on?

[kebab19]

Yes, of course you could bodge it, but providing you keep the bike you'd eventually have to grind the fekker back off again

[Lawrence]

Not a problem... I don't plan on selling this bike (it's not worth a lot as it stands, been written off at least twice lol) so as long as it all stays in one piece I'm more than happy to bodge.


Think I'll be calling my local dealer for a nut to see if it can at least try to hold it on :s  Then weld the nut onto the shaft.


Now I think of it it was making a funny noise on over-run earlier, shouldn't have ignored it   Wasn't loud and I thought it was me hearing things.

[markbubble]

if  its the thread thats a bit chewed you might be able to get it re threaded with a die to restore the thread,maybe drill a hole to put a split pin on or as some others have done use a circlip etc,welding the nut on is a last resort solution but if you do maybe just get a couple of tack weld on it so removal later is a bit easyer and id change your sprocket (and chain) for new before you weld it!

[Fazerider]

I wouldn't just tack weld it! I was too cautious the first time I welded mine on and the small amount of side-to-side free play the sprocket had was enough to break the weld after a few hundred miles. (I know there shouldn't have been any free play, but the thread was so knackered I found it difficult to get the nut tight enough prior to welding.)
After that I did a more thorough job and it stayed put. Come chain change time it's a simple matter to cut through the weld with an angle grinder and replace the sprocket. I eventually changed C&S that way three times in that engine's lifetime.

[phillywilly]

dont shoot me down in flames for this but....why are fazers prone for this problem and if you use a circlip do you drill a small hole through shaft or can it spring around shaft ?
has anyone used lock nut glue to any sucsess ?,apart from losing nut how much damage does it do to casing ?
soz to ask these questions on your thread but only had fazer for couple of weeks and want to learn from you guys before i have to change my chain and sprocket 

[Lawrence]

The original nut fitted was too thin (9mm as opposed to the 12mm thick replacement part) and can work loose.  Mine could well be original (I think it was 9mm but no way of knowing for sure now) and the bike has 33k on it.  I've had it since May when it had 24k and have checked it a few times, it's always been torqued up correctly.
 
There's not a lot of damage to the cover, few marks from where the nut has spun against it before falling off, but the main damage is done to the shaft which is an engine/box out and disassemble job.  I don't reckon threadlock would be up to the job tbh, the amount of vibration it must be subject to it'd probably still work loose.
 
My sprocket came off at about 10mph as I pulled away at a mini roundabout and looking at the shaft again I reckon it's saveable, although it won't be just a nut... welding is probably the quickest and most secure way I reckon.  Will just have to replace the nut whenever I do the chain/sprocket.  Just glad it didn't come off at 70mph as it would've been proper knackered then 

[markbubble]

if  you get the correct tread lock it will help and you can also get a similar thing to put on shafts to help hold things on slightly worn shafts(it takes up some of the free play) etc cant for the life of me think what its called,i used this aroun 15 years ago on a splined saft on one of my bubble cars and its still great now,id have thought a nut with a tack weld be good enuf but cant be if its already been tried and failed! a circlip(or e clip) would need a groove around shaft where as if its drilled it could be possibly used with a castle nut and split pin or maybe wired(like lot of race bikes) to stop it come undone,with any locking compound etc make sure everything is well cleaned before use!
 

[rjd1]

i got the nut and washer free from yamaha
they also fix shaft if its wrecked
there is a thread about this somewhare

[Lawrence]

Since I'm going there I'll ask, but I doubt they'll do it.  I don't think it's an original sprocket (the chain certainly isn't, says DID on it) and I have no history at all.. only paperwork I got with it was the bit of the V5 and MOT certificate 

[phillywilly]

i got the nut and washer free from yamaha
they also fix shaft if its wrecked
there is a thread about this somewhare

not really a play on words there rjd1  eh
as i say ,...sorry about hijacking this THREAD 

[Lawrence]

Would an Arc welder be suitable for doing this or would I need a mig?

[Fazerider]

Would an Arc welder be suitable for doing this or would I need a mig?

Yes, an ordinary old stick welder is what I used.
Don't do it if you're going to try to get Yamaha to foot the bill for a replacement shaft... I'm not sure if they're still honouring that deal, but they'll probably quibble if the nut's been welded on! When I first did mine Yamaha were still not accepting there was a problem... even if they had, I think I'd have done the same thing simply because I wouldn't want to leave the bike at a dealer for weeks on end while they fit in the work around more profitable jobs.

[Lawrence]

Nut/washer ordered, £8.23 from my local.  Should be with the Friday, got the day off so I can hopefully get it back on the road.  Thread doesn't look too bad so hoping I can get enough torque on it to hold it all together firmly before welding.

[Fazerider]

Don't forget to keep the chain out of harm's way while you're spattering molten slag around, or it'll do the O-rings no good.

[unfazed]

The problem is mainly due to the thread diameter of the shaft being to small for the nut thread diameter. General the shaft thread diameter should be 17.5mm many are less, minewas 17.2 to 17.3 and now 17.2 and 2 threads left. It does not effect all the 600 but any which have the problem appear to have a shaft thread diameter of less than 17.4mm.
I uploaded what I did with some pictures to fix mine and  put it I put it under
  Downloads » Manuals » FZS600 Fazer » How I fixed my Sprocket nut problem.
See also thread 'Front sprocket issues again'
Hope it helps

[Lawrence]

Threads turned out to be ok once the nut was on and I've torqued it up fully, threadlock, tab washer and then welded it on for good measure     My welding 'skills' left a bit to be desired but it's hidden behind the cover so I don't care 
 
Thought my clutch was buggered when I was putting the cover back on    until I actually looked at how the mechanism worked and realised that since the cover wasn't bolted up fully it was just pushing it away from the bike when I pulled the lever, rather than opening the clutch 

[limax2]

You did of course make sure you got the 12mm thick nut and not another 9mm one! Mind you I don't think that nut will be going astray this time which ever one it is. 

[Lawrence]

I didn't measure it but I'm pretty sure it is.  The nut sits flush with the end of the shaft.

[limax2]

I didn't measure it but I'm pretty sure it is.  The nut sits flush with the end of the shaft.

Yes that will be the 12mm nut then  . The old type nut sits about 3mm in from the end of the shaft.
Happy biking.

[Lumpy]

if the lock washer is used it will not loosen. Simples. If the lock washer is fitted properly that is.

[richfzs]

if the lock washer is used it will not loosen. Simples. If the lock washer is fitted properly that is.

Aye, right

[unfazed]

See post on Front sprocket issues again