Post by: Fazero on 28 June 2021, 01:30:34 pm
just wanna share with you the slight heart attack I got when I wanted to lube up the clutch actuation mechanism and found my front sprocket nut flopping around. It was hold on only by the washer.
For a brief second I saw myself tearing the engine apart 2 weeks before a big trip.
Luckily after some inspection there is no visible damage to the threads. Ordered the new nut and washer, some loctite and hopefully this will never happen again.
But still a little bad feeling to ride around with that issue back in my mind.
Post by: BBROWN1664 on 28 June 2021, 07:38:23 pm
Post by: limax2 on 28 June 2021, 08:59:36 pm
Post by: Disorderlypunk on 29 June 2021, 05:19:28 pm
Post by: Fazero on 03 July 2021, 12:50:26 am
Post by: b1k3rdude on 03 July 2021, 08:58:34 am
Ordered the new nut and washer, some loctite and hopefully this will never happen again.As this seems to be a common issue and as we need this kind of info for the FAQ I would like to ask the community the following question -
- There are different types of loctite on the market (https://foc-u.co.uk/www.henkel-adhesives.com/us/en/insights/all-insights/blog/difference-between-threadlockers.html), which is best suited to this particular application, I am thinking 'Red Locktite' - Gnasher?
Post by: b1k3rdude on 03 July 2021, 09:00:59 am
Today the new 12mm nut arrived. Cleaned the threads, put some Loctite on there for my head and torqued to 70NM. Hope the problem is solved :rolleyesLooking at your photo it looks like the splines on the output-shaft are still in good condition, so the inner part of the washer should engage properly with it. just don't forget to bend up the tabe on the washer after you have tightened up the nut.
Post by: Gnasher on 03 July 2021, 12:08:17 pm
I am thinking 'Red Locktite' - Gnasher?
If it's Loctite go for 270 green, but you'll need to apply heat first to remove it.
Post by: b1k3rdude on 03 July 2021, 01:32:11 pm
If it's Loctite go for 270 green, but you'll need to apply heat first to remove it.I assume a normal butane torch can provide enough localised heat for this..?
And if 270 green is the best/extreme, what the next best that doesn't require a blowtorch..?
Post by: Gnasher on 03 July 2021, 01:45:23 pm
I assume a normal butane torch can provide enough localised heat for this..?
Yep a good torch will reach 600.
And if 270 green is the best/extreme, what the next best that doesn't require a blowtorch..?
There isn't one, you run the risk of the nut undoing.
The use of Loctite as a way to secure FZS600 nuts that haven't had the lay shaft replaced, is totally dependant on the thread being undamaged and the use of the tab washer.
Post by: b1k3rdude on 03 July 2021, 11:11:48 pm
Post by: Fazero on 04 July 2021, 01:22:07 am
Could you school me on the importance of the washer? Of course I bend it but it should be only an additional security or am I missing something?
Post by: Gnasher on 04 July 2021, 10:16:05 am
I just used the normal blue Loctite. If this would ever loosen again I will probably go with Loctite 638.
638 is not a thread locker it's for holding/bonding flat cylindrical components i.e. gears on shafts.
Could you school me on the importance of the washer? Of course I bend it but it should be only an additional security or am I missing something?
The washer is what is supposed to stop the nut undoing, not the Loctite. The use of Loctite is a get around for a design flaw, to which there are two modifications, one redesigned nut, two redesigned (replacement) lay shaft. Just the nut can work, but this is dependant on thread damage to the shaft. Using just Loctite there's a high chance the nut will undo, using a lock/washer less so, but it can still undo, more so using 243 what was known as nut lock.
I would suggest you search on the site for sprocket nut and see what can happen. They don't just undo and fall off they destroy the thread on the lay shaft and the sprocket cover. Replacing the lay shaft is a engine out split the casing job, plus the cost of the shaft, which the last I looked is no longer available new.
I wouldn't advise using 243 or 638 but it's your choice, hopefully you'll get away with it.
Post by: celticbiker on 05 July 2021, 07:44:33 am
Another one here for loctite 243.
Post by: b1k3rdude on 05 July 2021, 12:17:10 pm
- That shadow looks like a tab washer was on there that hasn't been folded over.- Common mistake by people that dont know what they are doing.
- Another one here for loctite 243.
- Gnasher has recommended Green 270
Post by: Gnasher on 05 July 2021, 01:21:34 pm
The Loctite application helps prevent I repeat HELPS the threads from destroying themselves due to a design flaw, it can still happen especially if you use 243 or nut lock as it was known. I tried using it when this saga was first noticed, all still came lose using 243 it took anywhere between 2 - 6k but they all came lose. Using 270 as far as I'm aware to date, none I did came lose, the bikes I tested this on were a mixture of despatch and everyday commuters all weather bikes, doing up 2k a week. There's also a point where the threads are too worn even for 270.
It's up to you.
Post by: celticbiker on 05 July 2021, 08:19:07 pm
Then I'm not surprised that sprocket nuts come undone.- That shadow looks like a tab washer was on there that hasn't been folded over.- Common mistake by people that dont know what they are doing.
- Another one here for loctite 243.
- Gnasher has recommended Green 270
Mine is staked but I don't trust that so I use a bit of loctite.
Post by: Fazero on 06 July 2021, 12:44:21 am
The official Yamaha statement (Service Bulletin M2006-03, for FZ6 and R6, but the part numbers are the same):Use Loctite 620 and torque to 90NM with the new nut and washer...
So I was about right with 638 (choosed because of higher gap filling capabillites). Compared the data sheets and the 620 is better with higher temperatures.
Post by: Gnasher on 06 July 2021, 09:53:13 am
Here's what retaining compounds do:
- https://www.henkel-adhesives.com/uk/en/products/industrial-adhesives/retaining-compounds.html (https://www.henkel-adhesives.com/uk/en/products/industrial-adhesives/retaining-compounds.html) used to be reffered to as bearing fit.
- Here's 620 https://www.henkel-adhesives.com/uk/en/product/retaining-compounds/loctite_620.html (https://www.henkel-adhesives.com/uk/en/product/retaining-compounds/loctite_620.html)
- Here's 638 https://www.henkel-adhesives.com/uk/en/product/retaining-compounds/loctite_638.html (https://www.henkel-adhesives.com/uk/en/product/retaining-compounds/loctite_638.html)
- Basically the above secure bearings, bushes and cylindrical parts into housings or onto shafts.
- Here's threadlockers https://www.henkel-adhesives.com/uk/en/products/industrial-adhesives/threadlockers.html (https://www.henkel-adhesives.com/uk/en/products/industrial-adhesives/threadlockers.html)
- Here's 270 https://www.henkel-adhesives.com/uk/en/product/threadlockers/loctite_270.html (https://www.henkel-adhesives.com/uk/en/product/threadlockers/loctite_270.html) used to be reffered to as stud lock, the important bit is "The product serves to permanently lock assemblies which must not come loose." And as per Gnashers earlier comment on 270, you will need a handheld butane torch to heatup the sprocket when it comes to changing it - bkd
What the bulletin doesn't tell you and Yamaha didn't want to face because of cost. Is the the condition of the threads is vital, as that's where the problem is, machining tolerance, which is why some fail others don't. Meaning the lay shaft on used bikes could well be screwed, beyond this fix. In fact Yamaha did replace some shafts but all on the quiet, they didn't want a recall as it's a big and expensive job and are not alone in that approach.
Many manufactures will only recall when there's no other option. e.g. good old Hotpoint and their dryers springs to mind. Bearing in mind not all bikes were affected, Yamaha wanted to avoid a recall and have a cheap a fix as possible and one that would kick the problem into the long grass, which it did. If you slap on 620 and the threads are sufficiently worn, yours look worn, how much I can't say from a picture. It will still come loose, quite when is all dependant on how worn the lay shaft threads are, could be days, months even years depending on your mileage.
What I do know is if you use 270 the chances of it undoing are reduced further, bearing in mind you had on idea the sprocket nut had come undone until you removed the cover and looked. It's also possible your chain has a good few tight spots by now too.
The advice offered is to help you, it's up to you, if you use it. Stick on 243, 638 or 620 even superglue if you wish, it's your bike and pocket. Best of luck with whatever option you choose.
[I have cleaned up the post bit as this is very useful info and will link it in the FZS600 FAQ - bkd.]
Post by: Captain Haddock on 13 September 2021, 08:56:38 pm
Post by: StreetFzr on 28 September 2021, 11:27:01 pm
If anyone needs the new nut and tab washer kit I have one sitting right beside me, I sold my 600 years ago now, kit no. is 90891-10124.Anyone near south cambs. is welcome to collect it or cover postage.Hello mate, have you still got this nut and tab washer kit?
Post by: Paul on 30 September 2021, 01:47:27 pm
The sprocket nut is there to stop the sprocket sliding off the output shaft.
It doesn’t need to tighten flush with the sprocket to do this.
The output shaft is the fault on some of the fazers. The grooves in some output shafts are cut a slightly too wide.
This allows the sprocket to move backwards and forwards on the shaft when placed under load or off load.
Because the nut is tight against the sprocket it continually rotates slightly on the threads… wearing them out.
The answer in my opinion is grind down the flange on the sprocket nut so that when it tightens on the shaft it is simply flush with the sprocket but does not tighten against it…. And put some grease on the sprocket to further ease the junction between the nut and sprocket.
Therefore there is insufficient ‘grip’ between the sprocket and the nut to allow the sprocket to turn the nut.
In essence you want to tighten the nut up on the output shaft but not tighten it up against the sprocket.
Post by: Gnasher on 30 September 2021, 03:16:28 pm
Personal view
The sprocket nut is there to stop the sprocket sliding off the output shaft.
It doesn’t need to tighten flush with the sprocket to do this.
The output shaft is the fault on some of the fazers. The grooves in some output shafts are cut a slightly too wide.
This allows the sprocket to move backwards and forwards on the shaft when placed under load or off load.
Because the nut is tight against the sprocket it continually rotates slightly on the threads… wearing them out.
The answer in my opinion is grind down the flange on the sprocket nut so that when it tightens on the shaft it is simply flush with the sprocket but does not tighten against it…. And put some grease on the sprocket to further ease the junction between the nut and sprocket.
Therefore there is insufficient ‘grip’ between the sprocket and the nut to allow the sprocket to turn the nut.
In essence you want to tighten the nut up on the output shaft but not tighten it up against the sprocket.
Err no, on all counts.
The sprockets MUST not move in any direction or you get what's known as chatter, which is exactly what this issue was/is. I've changed many back in the day, some the nut was still locked up tight, others there's was no nut left, the sprocket being held on by the chain tension. The issue is the nut recess on some earlier nuts and the thread wasn't deep enough to lock against the sprocket and the layshaft shoulder when torqued up. This enabled the sprocket to chatter and wear the nut facing, which in turn destroyed the nut due to it being softer than both the lay shaft and the sprocket.
Post by: limax2 on 30 September 2021, 08:31:27 pm
Post by: Captain Haddock on 01 October 2021, 09:52:12 am
PM sent.If anyone needs the new nut and tab washer kit I have one sitting right beside me, I sold my 600 years ago now, kit no. is 90891-10124.Anyone near south cambs. is welcome to collect it or cover postage.Hello mate, have you still got this nut and tab washer kit?
Post by: Paul on 01 October 2021, 01:26:18 pm
The reason why the threads wear out on the output shaft and the nut, is in my opinion due to sprocket chatter.
The reason why you get sprocket chatter is because the sprocket and output shaft aren't a tight fit.
If you can hand push the sprocket onto the output shaft, you'll likely get some sprocket chatter.
In essence if you have to tap it on with hammer you should be o.k., but if you can push it on by hand then you could end up with problems.
I put 110,000 miles on my last Fazer, and changed the drive sprocket several times, fortunately I had to tap it on with a hammer, and thus never had problems.
A guy I knew who also had a Fazer, had the sprocket nut issue, and he found his sprocket was a push fit onto the output shaft.... it didn't need tapping on.
Post by: Gnasher on 01 October 2021, 04:34:26 pm
The reason why the threads wear out on the output shaft and the nut, is in my opinion due to sprocket chatter.
Yep, I told you that ;)
The reason why you get sprocket chatter is because the sprocket and output shaft aren't a tight fit.
Nope :rolleyes see my last. The sprocket must be a loose push fit to allow for shaft expansion and easy extraction. If not the drive splines will become damaged i.e. burred and you'll struggle to get it off without a puller or a your No1 tool a hammer. :D
If you can hand push the sprocket onto the output shaft, you'll likely get some sprocket chatter.
Nope. Not if sprocket is pushed up against the lay shaft shoulder by the lock nut, once it's torqued.
In essence if you have to tap it on with hammer you should be o.k., but if you can push it on by hand then you could end up with problems.
Nope, I've worked on bikes for 30yrs and still do. I've never put a front sprocket on any make of bike with a hammer, total DIY crap :rolleyes
I put 110,000 miles on my last Fazer, and changed the drive sprocket several times, fortunately I had to tap it on with a hammer, and thus never had problems.
Good for you :) Shame you didn't tell Yamaha then, save them issuing a workshop bulletin after their experts found the issue. Oh course they were wrong all the time, Paul had the answer :rollin :rollin :rollin Your lay shaft splines are most likely burred :rolleyes
Not all were effected.
A guy I knew who also had a Fazer, had the sprocket nut issue, and he found his sprocket was a push fit onto the output shaft.... it didn't need tapping on.
See above all front sprockets are loose push fit.
This is all very old and very well documented. If you wish to have these half barked theories, I'd keep them to yourself, bloody funny though :lol :lol
Post by: FazThou on 01 October 2021, 07:36:42 pm
Post by: b1k3rdude on 02 October 2021, 08:46:02 am
Post by: Gnasher on 02 October 2021, 12:41:48 pm
:lol :lol :lol got me popcorn ready :lurk :lurk :lurk :lurk
You don't need you're popcorn mate, there's nothing more to be said, not from me that is :)