Originally posted by slidesvill on 27/06/04
This seems to be getting a common problem, and I'd like some info off the foccers that have lost your front sprocket nut. I consider this as a fault with the FAZER, and intend to email/speak to YAMAHA over this problem, I think they should look into this before something serious happens...
Could you please let me know the following
1, Year of the bike
2, Mileage
3, Was it the original chain and sprockets
4, Was it a warranty claim
5, Did you have an accident because of this fault or been put in a dangerous situation.
Please give me your input.
slidey
Reply posted by Alan Sherman 26/07/2005
This happened to me twice now. Basically the lock washer retains its splines and the bent over tabs so we can totally discount the nut actually unscrewing as a cause of failure. What fails is the thread on the nut (the threads on the shaft remain in cases where the damaged nut is found quickly).
Possible causes of nut error are:
User error: Too high a torque used in assembly for the nut.
I think this can be discounted due to the large number of people that have had the problem - a lot have never removed the nut since buying the bike. The torque value is well known in the manuals and it is easy to apply a torque wrench to the nut.
Manufacturing fault; perhaps there was a batch of faulty nuts or driveshafts - either physical or material tolerances out compared to the design spec.
I think this can be discounted as the nuts have failed on a number of bikes (including models) across the range of years of manufacture.
Poorly designed / specified nut / driveshaft interface. Basically the combination of very fine threads, the low number of threads that are actually used to take the load, the specified torque, perhaps the tolerances specified for the nut / driveshaft mating surfaces and the nut material is a poor combination for the designed use.
I really think this is the problem as the nuts have failed across Thundercat, Fazer (and did I hear R6 too?) models, and across the production years. It's be interesting to see what other bikes use the same nut part number and see if there are other problems. I'd hope Yamaha are looking at this.
So what happens now? Yamaha are very closed about it all - not surprising really when you think about the cost of a recall to fit new nuts to the thousands of bike on the road. But going further there is also the implied liability that goes with it which would require Yamaha to replace the driveshaft for people that have had the nut fail that has in turn damaged the driveshaft threads (this job involves taking the engine out, splitting the cases and stripping down the gearbox to replace. It is awfully expensive). All this for discontinued models.....
I am surprised that Yamaha have not changed the design of the nut yet (they hadn't when I ordered a couple in February). They did change the design of the speedo sender drive - the new one is much improved and doesn't break when refitting the wheel so easily.
A new longer nut with a larger number of threads to spread the load, perhaps a revised (lower) torque and maybe a material change would probably solve the problem. I believe someone was trying to get a nut made up at work along these lines.
If we were to gather the evidence in a structured way (bike model, year, vin code, mileage discovered, any replacement chain and sprockets fitted, who fitted etc) to build up the evidence then we could put a strong case to Yamaha (they have already been shown this thread however).
With no response from Yamaha to rectify the problem we could go to the media. We would need strong evidence though.
Reply posted by slidesvill 27/07/2005
The list I noted down of foccers that have lost their gearbox nut/sprocket are:
BOBW (X3)
PEPY27 (X2)
SNOOKY
ICE EAGLE X2
ALISTER X2
BLUE ONES ARE FASTEST
ZARNIWOOP (Loose)
GRIPPA.G
DON BROWNING
RUBBERMAT (X2)? (Plus Stripped Gearbox Shaft)
PETE 786
FUNKY UK
ZIGGY COL
ALPINE
SLAYER THE LAWNMOWER MAN
ALAN SHERMAN (X2)? (Plus Stripped Gearbox Shaft)
MOOK (Loose)
OLD SON
HAWRANEK
FASERJAY
BEN DIESEL
COOLRIFFS
RICOU
MIKE T
ROCKFAN
SLIDESVILL (Loose)
This problem also effects THUNDERCATS, I've been contacted by there owners club, well it's the same motor!
So far we've contacted Yamaha UK and they are aware of the problem, they have passed it onto Yamaha Japan but we've had nothing back.
I've done several emails to mags, such as Bike, Ride, MCN...but had nothing back, even tried BBC Watchdog nothing
Will compose another email next week but won't hold my breath........isn't there somewhere you can lodge mechanical problems that haven't been recalled, sure I remember someone posting about this??? any idea's....
slidey
Updated list 31 01 2005
Wascommuter (Loose)
Fazer Jett (Loose)
ZiggyCol (Loose)
MikoFZ1
Gordo (Loose)
Fazer Racer (Plus Stripped Gearbox Shaft)
Gnasher
Fieryblue
fazerboy01
pete786 (X2) (Plus Stripped Gearbox Shaft)
Duggy
Lum
Weedon (Plus Stripped Gearbox Shaft)
Fazfighter (Loose)