Sprocket strange wear ?

[jerry]

Due to extreme clicking noise from Drive train

I have just changed the chain and sprockets on my S4 after 11882 miles of use ,,mew sprockets are JT 525 15 =42 both steel and a new RK 525 XW gold chain

but something strange about old chain and sprockets ,, the 525 -43 renthal alloy rear is still within usable limits its not hooked and wear is minimal .

the Tsubaki 525 gold X ring chain has vitually no wear or stretch it does not have any bad links , stiff spots ond no lateral bend unlike a very worn chain , it actually measures up within specs and obviously still has a lot of life ????


however the Standard Ducati 15 -525 front sprocket which was new at same time as the rear and chain is completely hooked to death ????? that was the cause of the horrendous noise ,, im trying to understand how this could be so badly worn compared to the other 2 items ???

any ideas its purely academic as they have all been replaced .....but I kept the old chain as an emergency spare ...

[utopia]

The only thing I can think of is that you have got hold of a front sprocket which has somehow escaped the normal heat treatment process.
It sounds unlikely but I can't think of anything else.
You could try testing it with a file on an unworn surface somewhere.

[Aviatore]

Perhaps because there are fewer teeth on the front to spread the load compared to the rear sprocket. Making each front sprocket tooth carry more strain per tooth as well as having each tooth engage a chain link more frequently than a comparable tooth on the rear.

[Dukedesmo]

Perhaps because there are fewer teeth on the front to spread the load compared to the rear sprocket.

Yes, but with the rear being alloy you wouldn't expect this rate of wear.

My M900 munched through 3 Renthal Hard Anodised alloy rears in less than 5,000 miles but the front steel sprocket is still good.

I would agree with Utopia and suspect a 'soft' front sprocket.

[Flip]

The only other thing I could think of other than the above (although doubt this to be the case knowing your mechanical ability) is that it has been ragged around with a very loose chain.
As I say, I am sure not the case but all I could think of.
Just for info- it was my Afam chain that was knackered while both front and rear Afam sprockets were still serviceable when I changed mine last year after about 10k miles.

[jerry]

Its a weird one,certainly , im very anal about chain adjustment and lubing ,its not a big deal as it has all done 11,800 miles ,which is not unreasonable ,but i would have put money on the rear sprocket and chain being more shagged out than front sprocket ...... weird ,, any way bike has a fresh set of everything so no worries ..

[Dookbob]

The other thing that could explain this annomoly is the crap bits of kit that can find their way onto the market disguised as mainstream manufactured parts. I notice that the Indians are now competing with the Chinese to see who can con us into buying the worst pieces of junk imaginable.

[jerry]

Dookbob ,,I hear you but that front sprocket was a ''genuine '' Ducati one ????

another theory is that the gunge that accumulates around the front sprocket , oil, chainlube goop, road grit ,could have become a kind of grinding paste ,,
but i regularly clean all that crap out ,, and am now using a chain oiler so its a moot point ,,

reckon it was just a dud part.but will be monitoring this item on all my bikes ..

[Drumnagorrach]

Dont be fooled by seemingly authentic markings ,SKF have recently discovered £40,000 worth of counterfeit bearings in a north east bearing factors .They were indistinguishable from genuine by eye ,only a very high failure rate got questions being asked . I learned that SKF can tell in their lab ,it has got so bad that they have a secret tell tale ,needless to say,they didn't tell me what it was.
I only learned of this counterfeit problem through premature bearing failures on a 400kw motor that had engineers from SKF over to check what we were doing wrong.

[utopia]

That's interesting, slightly scary and I guess, not too surprising.
Its the way of the world these days, I suppose.

I also pondered the gunge around the front sprocket acting like grinding paste, but I discounted it because it would probably affect the chain just as much and I doubt that the rear sprocket would escape either, particularly an ally one.
Can't really see how it would cause wear to be limited to the front sprocket.
And of course, I knew you'd be keeping it clean in there anyway. :)

[Drumnagorrach]

Front sprockets used to be " as hard as a whores heart " as my old boss would say . I turned the teeth off an old Bonneville sprocket ,to keep the splined hub for mounting a bigger sprocket, to get more top speed out of an old T140 V . The torture it put a carbide tool through ,the growling and amounts of steam produced brought much derision and ridicule from my workmates . Case hardening in Birmingham was deep and formidable ,probably not so much in Italy .

[Dukedesmo]

Case hardening in Birmingham was deep and formidable ,probably not so much in Italy .

I bought a Renthal front sprocket for my Monster and the threads were not cut all the way through so I couldn't get the retaining bolts in.

I tried to run a tap through it but there was no way it was going as the metal was way too hard so I sent it back for replacement.

Years ago on my Ducati 250 scrambler I changed the front sprocket as it was badly worn, I didn't change the chain or rear sprocket because they appeared to be OK. The new front sprocket was worn down to almost circular within a month, presumably due to running a worn chain around it?