Just got back from a run out and decided to checkout chain tension.... Something did not 'feel' quite right - found that the sprocket retainer had been pulled onto drive shaft. I'm now concerned that the shaft is damaged and will need replacing - advice please.
The shaft looks ok to me get some new locking washers and a new front sprocket and you should be tickaty boo!
Two retainers in picky - bottom one is new top f****d. I'll put the new one on and take it easy for a few miles - then remove and inspect to see if it is OK. What worries me is why this has happened and how bad it would be if the sprocket had come off rather than go further onto the shaft.
Doubt the sprocket would move enough to come off, it's impossible to remove the sprocket with the chain adjusted properly. Steve.
Thx fujack, birdie. The chain was adjusted correctly - but when this happened it seemed to have become much too tight. I was running with 14 tooth front. I think. I'll go back to standard 15 tooth for a while - and get some spare retainers!
If you managed to take the front sprocket off without slackening the chain it would suggest the chain was to slack
I had one very similar.......no permanent damage, but I don't really like the small amount of movement of the sprocket on the shaft even with a new retainer.........I guess it keeps the chain in line a bit, but I think it is a wanky way of keeping a sprocket on a shaft. I inspect my retainer about every 500 - 1000 miles and always keep a spare. AL
Sound advice - I'll certainly be doing this in future - I'd hate to have one go badly wrong at speed!!
It's still a sh*tty way of holding a sprocket on a shaft.......I reckon SteveB (duc904red) should start knocking a few out in a better material.
I think you may be right about that..............Maybe good quality stainless would be better...........or certainly something better than the pressed slice of cheese..... AL
I once took the sprocket cover off my 916 to find the retainer completely missing, I assume the screws came out because the inside of the cover was marked. Don't know how long it was without but didn't cause any problem as the sprocket won't move far (although I wouldn't recommend you try this). As an aside I recently bought a brand new Renthal front sprocket on which the threads are not cut properly, so the screws won't go in but the damn thing's so hard that I can't re-tap the threads... :frown:
I've just got everything back together with a nice new, 'made of cheese' retainer. On reflection, I'm inclined to agree that titanium is probably too hard; stainless might be a better material than the original. My only issue now, is to make certain the wheel is correctly aligned (it's an ST4s BTW) and the chain tension right! The markings on the swinging arm are crummy at best - so I've just knocked up a bush that is a nice fit in the spindle and makes measuring distance from swinging arm centre and wheel spindled centre easy. Now if only I can find details that tape measure.... Bush is double ended with different diameter each end.
Regardless of how wanky I think the method of holding the sprocket is; the retainer is worn by one thing only……Movement. I don’t know about your bikes, but when I fit a genuine new retainer plate, it is actually a bit loose in the shaft groove……by loose, I mean that the plate is too thin for the groove. If this intentional by Ducati for chain alignment or something, I haven’t got a clue, but as the sprocket and shaft are similarly hard steel, the shaft itself doesn’t appear to wear, just the retainer plate. When I fit a new plate and the sprocket, and get it all bolted up, the sprocket is decidedly wobbly, caused by the loose retainer teeth in the groove; consequently there is the potential for a lot of movement. Therefore, if a tighter fitting retainer plate was used, it couldn’t rock so much in the groove, therefore reducing the movement….. It’s my theory only, but I have a new plate here so I can always measure it and the shaft when I get five minutes and produce a decent accurate Cad drawing. AL
That's the one, the threads are OK on the other side of the sprocket but where they reach the side you want it's as if they only ran a taper tap through it. I tried running a tap through but it just stuck and I can't/daren't turn it because it'll break.
Arquebus - I agree, sprocket is decidedly wobbly. While I had everything apart, I chose to put original 15 tooth sprocket back on mainly because this seemed a rather better fit than the 14T I have been running for the last 12 months.
To update on the front sprocket, I returned it to Renthal who replaced it FOC. I recently bought a 41t Renthal hard anodised rear sprocket for the Monster (should be the same as an 851/888?) although it may have been old stock...
