Chain alignment issues.

[utopia]

Its ok, I'm not in need of advice and the story has a happy ending.

I was fitting this new chain and sprockets, so I thought I'd take the opportunity while everything was clean and accessible to just check the chain alignment.
I've had a look at it before one way or another, including the use of Capo's laser device as well as close inspection for any uneven wear on the sprockets, and I was fairly sure that everything was lined up fairly well.
I'd never actually checked it with a straight edge though.
But I had checked, and slightly adjusted the wheel alignment when I first got the bike, so I knew all was well there.
My usual method, in lieu of a long straight edge, is to (carefully) use a length of heavy gauge fishing line stretched tight. This method suggested a misalignment, which surprised me and made me suspect the suitability fishing line method on such a short run. Or maybe my eyes just weren't good enough anymore to be able to do it accurately that way.
So I had a scratch round in the corner of the shed and came up with a 2ft length of 8mmx25mm ally bar which looked to be straight and a handy size. As a final check I laid it on the glass of the kitchen window and checked for bowing with a thin feeler gauge ...it passed.
So, to get to the crux, there was indeed a misalignment....of about 10mm.
Coincidentally, the sprocket has a 10mm thick boss/flange on one side, which the manual states should be innermost, as it was when I bought the bike with only 2000 miles on it.
Reversing the sprocket gave me perfect chain alignment.
There is a certain amount of slop in the driveshaft splines, but even averaging out the two extremes, the alignment was spot on with the sprocket the "wrong" way round.
Even more peculiar, the little plastic rub strips on the swingarm had never aligned correctly with the chain rollers, but instead with the inner plates. But now these strips align perfectly with the chain rollers.
And on top of all that, the chain even felt slightly more slack (with the adjusters in the same position), suggesting that the alignment had been improved. Ok, I could have imagined that bit, but I honestly don't think I did.

So what's the story here then ?
It seems very peculiar that everything else should fall into perfect alignment when the sprocket is switched round.
Have I stumbled on some weird miscommunication which has led to the spec being arse about face, or is it just coincidental accumulation of manufacturing tolerances on my particular bike ?

Either way, I'm happy as everything lines up nicely now, and there's the added benefit of less leverage on the gearbox output bearing now the sprocket is further inward.
Just goes to show though, its always worth checking.

[Wildfire]

Very interesting post Jeff. Chain alignment on the Monster has been a constant issue for me.

You're next challenge is to machine up some new chain adjuster blocks that don't move when you try and adjust the chain.

[utopia]

I always completely ignore the markings on the chain adjuster blocks.
If you think about it, the cumulative tolerances on all of the components in the assembly, ie swingarm, frame, engine, adjuster plates etc are so large that the marks stand very little chance of being accurate. After all, I strongly suspect that the adjuster marks on each side of the swingarm are made before the arm is welded up, so their final accuracy has to be rather suspect.
In fact, I've replaced my chain adjuster plates with plain washers, so there are no marks on them at all.
Having initially checked the wheel alignment with a straight edge, I have marked the adjuster bolts so their position relative to each other is easily maintained, ensuring that the wheels stay in line.

Only today I heard a quote, attributed to a well known Ducati dealer of repute, that the day he received a new Ducati from the factory with the wheels less than 10mm out of alignment, he'd eat his hat.
I can accept that, but the same degree of misalignment on the chain is a much more serious issue, in my opinion.

[Dookbob]

Could this have been part of the reason for your chain guard being nowhere near lined up correctly?
Just checked my sprocket, the boss is outermost. I line mine up with a laser but to be honest I don't find it any better than a straight edge held against the face of the rear sprocket.

[utopia]

If you mean the little plastic rubbing strips that protect the swingarm from the chain then yes, I do think that there is a connection.
But that connection is a weird one, because the sprocket was definitely on the correct way round before, according to the published spec. In fact I very much doubt if it had been disturbed at all since the bike left the factory, until I bought it. And I certainly have not replaced it the wrong way round.
Therefore I'm inclined to think that the published spec is wrong. (a dangerous viewpoint I know, but nothing else makes any sense).
10mm is a relatively big misalignment, too much in my opinion to be likely to be due to cumulative tolerances. And how coincidental that the boss/flange is also exactly that amount, restoring perfect chain alignment when fitted "back to front".

So, 750 owners (mine's a 2000 model), check your chain alignment.
And when you do, use a good, old fashioned straight edge rather than a laser, who's high tech nature can fool you into thinking that its a better tool for the job.........it isn't.
You may well find that yours is 10mm out too.
In fact, this may apply to other models as well

It couldn't be, could it, that in the 20th anniversary year of the monster, I've stumbled across a chain alignment error that nobody else has spotted in the previous two decades ?
Surely not. :confused:

[slob]

I take it the 10mm boss is on the front sprocket Jeff?

I think you'll find that 600/750 and 620/800 have the boss outward to line up with the sprocket on a 4.5"rim/160 section tyre and the boss goes inward on a 900/1000 to clear a 5.5"rim/180 section tyre.

[Capo]

It couldn't be, could it, that in the 20th anniversary year of the monster, I've stumbled across a chain alignment error that nobody else has spotted in the previous two decades ?
Surely not. :confused:

If you do a bit of research you will find that this has been previously identified

[Dookbob]

I have come across this dilemma before, but not on here. A pal of mine with a M600 called me to say he had removed his front sprocket to mess with the chain and forgot which way round it was fitted. He looked in his Haynes manual and it clearly showed the sprocket boss fitted innermost, but he wasn,t happy with it that way round. So I took a look at mine which I had had apart a couple of times and had refitted it with the boss opposite to the manual, ie. with the boss facing outboard. So that makes at least three of us with the sprocket fitted boss outermost. I,m sure it's just another example of the Haynes syndrome.

[Dookbob]

I just read Slobs post, which answers the question .

[Capo]

The 5 speed engine is also narrower which could explain the offset

[utopia]

Not the Haynes syndrome....the info I have is in a genuine Ducati manual.
The only discrepancy is that its for an '01 model while my bike is from 2000, but apparently it is the correct recommended manual for my year.

Yes, Rob, the boss is on the front sprocket, and I must admit I did wonder whether this had something to do with the wider rim fitted to the 900 etc.
It has also been suggested that its something to do with whether you have a five or six speed box (mine's five).

My judgement of the bike's two former lady owners, neither of which did more than 1000 miles on the bike, is that they are both extremely unlikely to have touched the front sprocket ....or anything else for that matter. Though I do accept that this is only an educated assumption.
Other than that, the bike has only been touched by Ducati dealers during its guarantee period, and since I bought it at 2000m, I've done all my own maintenance (and there is no way I would replace the sprocket the opposite way round to "as received".)
Therefore I think its quite likely that there has been a bug in the system somewhere which has resulted in the sprockets sometimes being fitted the wrong way round.....particularly when you consider the error in the manual.
I would advise all owners of such monsters to check their chain alignment.

Thanks for the responses.
The situation is now a little clearer.

[Mr Gazza]

This issue is going to come up time and time again if the manual is wrong. Maybe this should be made sticky so's not to be lost?

Just to add my own tuppence worth....Regarding the ie and Sie models from about the 1999 to 2002 era. (Definatly 900's . not sure about 750's and 600's?)

They have a special sprocket with a 5mm offset, not 10mm.
So it has a 5mm boss on both sides and can be fitted either way round to achieve the same thing.

Unfortunatly these can be difficult to find, and certainly only 15t ones appear to have been made, so changing ratios is only possible via the rear sprocket.

However I have found that a normal 10mm offset sprocket can be used with the boss innermost and a 5mm thick spacer beneath the retaining plate.
My spacer is home made from 5mm dural plate. It is a simple ring with two holes for the screws. I feel that a nice machined job the same shape and size of the retaining plate (minus the splines) would make a perfect job of it.

The only other thing I did was change the 15mm x M5 screws for 20mm so they enter the sprocket by the same amount as before.

Now I could if I wished, fit standard sprockets with any number of teeth using the spacer.

[utopia]

Yes, I remember your sprocket issues from a while back, Gazza.

I had a closer look at my old sprocket today, and I deserve a kick up the arse because if you look closely enough you can see that the wear is uneven.
Also, Capo tried his laser again on the realigned chain run, and with it positioned on the rear sprocket, the beam now hits every single outer sideplate all the way along the lower chain run, right up to the front sprocket, without touching the inner plates at all.
Though I still prefer the old fashioned straight edge method myself.

Tomorrow, I will get my mate next door to scan the pics from the manual, which clearly show the sprocket the wrong way round, and I'll post them up.
It seems likely that the folk who did the manual in the first place transferred certain sections from earlier manuals, without adequately checking that they were fully compatible.
Poor show really, but its Ducati, so I forgive them.

[gary tompkins]

I measure from swing arm spindle to middle of axle on both sides to check alignment

Marks on adjuster plates are useless

[utopia]

I measure from swing arm spindle to middle of axle on both sides to check alignment


Without meaning to be controversial.....
To be honest, I wouldn't do it that way myself.
I can see that it would check that the two spindles were parallel, and that would be useful, but not that the wheels were necessarily in line.
And it wouldn't have detected my sprocket misalignment at all.
And also, its perhaps not an easy measurement to take accurately.

I check my wheel alignment using a length of 20lb sea fishing line, with a link swivel on each end.
I'd explain the method, but it'd get very wordy and boring.
The beauty of it though, is that the line is guaranteed to be straight when pulled taught (between two heavy objects) so you don't have to rely on a "straight edge" of dubious straightness.
And I can store it in a tiny plastic bag....I've used the same line for years.
But most importantly, it checks the wheel alignment directly, at the wheels themselves, so any cumulative errors in other parts of the bike are eliminated.

[Dukedesmo]

I measure from swing arm spindle to middle of axle on both sides to check alignment



I've found that the paddock stand spools welded onto the swingarm are exactly the same distance back from the swingarm spindle on both sides.

So I now use a vernier inside the hole in the spool to inside the axle for the same result, only easier/quicker to measure.

[gary tompkins]

My steel swing arm hasn't got the spools for paddock stand like the alloy arm

That's why I use the spindle