front drive sprocket nut

[taliesin]

just had a chap come into workshop,lost his final drive,picked his bike up,on inspection we found his front sprocket had come off(nut was missing)very strange you might think,but looking on the web,this is a fault on at least 3 bikes,thundercat,fazer,r6,check out www.foc-u.co.uk

[taliesin]

sorry,if the web page dont come up,try searching for lost your front sprocket and washer,then click on www.foc-u.co.uk

[vinny]

just done a chain and sprocket for some ones fazer 600 looks like it had been swapped before for a iris chain the front sprocket was loose could have probably turned it another 2 turns by hand before getting it tight and the washer was bent over so couldnt see how it could have come loose

[alanTDM]

This happened on the TDM i got,well it did.
After i replaced the OM chain/sprockets with after market the nut worked loose about 2mm-3mm even though it was torqued to 70nm/50ftlb and tab bent over.This happened again after a few chain replacements later aswell
In the end i looked on the TDM web site and then i gave the threads a good clean,i got a new nut and loctite it on and bent all the tabs over.Its been ok ever since.
I think the problem is the nut itself,prob one of those thats ok to use twice but after that you must fit a new one. Similar to a Nyloc nut.
At first i thought it was the sprocket shaft splines worn or a bad sprocket i was using but all were ok.Never heard of the nut coming right off on a TDM though.

[silly_simon]

Yamaha can supply a slightly different design nut to combat this problem

And yes it is a common fault on the mk1 & II Fazer 600 but to my knowledge not of the 1000 :-/

The Nut doesn't actually come right off the end of the input shaft but comes off sufficiently to strip the shaft end resulting in a strip down and new shaft etc

[taliesin]

on the R6 that came in,the nut was completley missing but the tab washer was still there.Fowlers didnt even know about the up graded nut until we gave them the part number >

[alanTDM]

So wonder if this upgrade covers a wide range of Yamaha bikes which all have the same size nut problem.Have you got the Part number?i can check on the TDM parts manual i got.
Not so much the first digits (model ) but the middle and last but thats prob -00.
Great if you can supply that for future reference

[taliesin]

hi,the part number for the old nut is 90179-18020, the part number for the upgraded nut and lock washer kit is 90891-10124, hope this is help full,

[NiteW4tcher]

had same problem on a drz400sm...........except you are made aware of the problem by the amount of oil sat under bike...as there is a oil seal behind that uses the nut to seal it

[taliesin]

you would think if it was a problem with these bikes,that they should of got a recall,who wants a sprocket coming off at speeds :'(