Sprocket Alignment *IMPORTANT*

discussions specific to the 750 Paso

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delagem
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Sprocket Alignment *IMPORTANT*

Post by delagem »

I received some information that I felt was important enough to warrant a new topic. Bikerbard forwarded me the following excerpt from Ian Falloon's book, Ducati Belt-Drive Two-Valve Twins:

"There were also some problems with the lining up of the engine and rear wheel sprocket causing chain misalignment on some 750 and 906 Pasos. If not rectified this could result in the chain breaking. The factory realized this and supplied an alternative countershaft sprocket plate (827 1044 1A)."

I spoke with one of the best Ducati dealers in the country, Tom Fournier of Dunbar Euro Sport in Brockton, MA about this. Tom says this is a thicker sprocket plate designed to space the front sprocket over to more closely align with the rear. He also says that this part is obsolete.

If you take your chain and chain guard off, a straightedge such as a metal yardstick can be placed across the rear sprocket, and seeing where it lands on the front sprocket will show if there is a problem or not.

If there is a problem, Tom recommends first disassembling the rear eccentric. He said most are keyed and can only go together one way, but he has seen some that are simply splined all the way around, and can be assembled a tooth or 2 off, causing a rear wheel misalignment. If everything is assembled correctly, then Tom suggests getting some shims from a machine shop to place between the sprocket locking plate and the sprocket. These are similar to washers but tougher, and available in a variety of thicknesses.

I would just like to mention that in finding a new bottom end for my bike (after a chain broke the case!), I spoke to several dozen people who were parting out their Pasos. The overwhelming reason that people were parting out their bike was a chain breaking, destroying the case!
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Post by Finnpaso »

I think, MOST of those "broking cases" are caused by wrong chain lubrication(and not enough carefull chain condition checks).... But surely that lining is good to check, when changing chain. That wrong lining is very rare and it belongs to earilier Pasos only... They fixed that in factory quite early, when they realized it. Anyway, good topic to check that. :thumbup:
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Post by delagem »

Here's a pic of how I did the sprocket alignment check prior to fitting my new chain and sprockets. It is easier to do if the chain is off, but if you rivet the chain like I do, you can derail the chain and hang it up out of the way using safety wire or something.

Image

Image

As a side note, I was talking to a Ducati dealer about getting sprockets and he said "good luck", took him almost 3 months to get a set. However, I called Sprocket Specialists, and even though they were special order, I got them in about 2 weeks.
The $900 Paso: DellOrto's, Dyna 5 ohm coils, Ignitech TCIP4; finally, a new set of tires! Goldentyre GT070/071

The bike is gone, but the nightmares continue...
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Post by jcslocum »

Mike,

Looks like you have it sorted. Did you measure from the side of the side of the rear sprocket as shown in the picture or up higher where the chain actually runs?
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Post by delagem »

I measured as shown in the photo, which does put in a 1mm error, but close enough for the accuracy I need.

I did finally get the eccentric apart, and the problem was my inability to look at a parts blow-up and think, not that the parts were all that frozen. My eccentric is keyed and splined, not just splined, so that wasn't my problem.

I thought I was going to have to add a post on the "Lowering My Paso" to warn about sprocket interference with the chain guard, but when it was all assembled my 42 tooth sprocket just barely fits. But I don't think a 43 would...

Here's a pic of my new chain and sprockets, isn't it pretty?
Image

I run these DID520ERV2 and 3 chains on everything I own, and just for laughs, I measured the difference in length between a brand new chain and one that's 10 years old (on the 900ss that I'm restoring), not even 1/16" stretch on a decade old chain...
The $900 Paso: DellOrto's, Dyna 5 ohm coils, Ignitech TCIP4; finally, a new set of tires! Goldentyre GT070/071

The bike is gone, but the nightmares continue...
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Post by spaz »

As the owner of an 87 Paso 750, I also am very unhappy with Ducati concerning misalignment between the countershaft sprocket and the rear wheel. I probably changed the rear bearings at least 10 times, 2 front sprockets and ended up tearing up the output shaft bearing. All this time taking my Duc in for service and buying parts (bearings, sprockets and chain) and never being told there was a common problem concerning this. Fast-forward 17 yrs (thats how long the Duc has been in storage), 4 kids, a few jobs and numerous times I was going to put it back under me the time has finally come. Now the problem I have is none of the parts needed are available. So if anyone has any suggestions, or a bottom end I could purchase please reply.
Ducaddicted

Post by Ducaddicted »

Last saturday i went by a local ducati mechanic. I told him
about changing the sprockets (rear and front) and chain on my
paso. I asked him if the sprockets are still available on the market.
He assured me that wouldn't be any problem, BUT Ducati
changed Three times of gearbox during the making of the Paso.

So he said take off the sprockets and let me see them. Then
i can tell you what you exactly need.

Does anybody of you know of this story, changed gearbox 3 times ?

Is that why you have to be careful for a misalignment of the
sprockets ?

Do you take a O-ring chain on the paso ?

greetz,

Steven
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Post by Finnpaso »

I have read, that they changed gearbox at least 2 times in Paso.
I use x ring chain. It rolls easier, than o ring chain.
Antti http://www.youtube.com/watch?v=HeKOh3XoXPg&NR=1
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Post by delagem »

O ring or X ring doesn't really matter; just don't buy a cheap chain! I hadn't heard about changes to the gearbox, other than the varying thickness locking plate. That part isn't even produced anymore, but shimming the sprocket is easier still.

I wasn't aware of various sprockets available for Pasos either, and neither is Sprocket Specialists. They only offer the front in 14 or 15 tooth, and rears are special order, regardless of size. Guess they don't get many orders in anymore!
The $900 Paso: DellOrto's, Dyna 5 ohm coils, Ignitech TCIP4; finally, a new set of tires! Goldentyre GT070/071

The bike is gone, but the nightmares continue...
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Post by Finnpaso »

I have never heard different front sprockets offsets to 750 Paso, only that one. Surely some have also other Z, than that original 15, maybe Ferracchi, but about different OFFSETS? :confused: Anyway, there are very many OTHER Ducati modells, where can get front sprocket to Paso, cause they use same "output shaft" in those times in all modells..... Need to know only exact offset, what are looking for.....

Btw, if someone is looking front sprockets (Z=15) to 1989 750 Sport, i have 2 for sale :evil:
Antti http://www.youtube.com/watch?v=HeKOh3XoXPg&NR=1
KTM 990 Adventure -08 metal dark grey
Paso 750 -89 red/metal grey
907IE -91 red/metal grey
907IE -91 red
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sprocket carriers - 17"

Post by ducinthebay »

If you have changed to 17" Brembo rear wheel, you should know that there are two different sprocket carriers. The one that came on the 4.5 wheels moves the chain farther inboard than the one that came on the 5.5 wheel. Both of the carriers fit both wheels, and are interchangeable. It only affects your chainline.

As best I can surmise, there are three different front sprocket offsets. The Sport is the furthest outboard with the welded washer on the sprocket and the 8mm fixing bolt. Next is the Paso that is shown in the picture a few posts up, and hard to find. And last is the Monster/SS sprocket that is the furthest inboard, and common as dirt. If push comes to shove, and we can't find front sprockets anymore, having a shop weld on a thick washer to a newer, more common sprocket may be just the deal.

Are all Paso output shafts threaded inside for an 8mm bolt?

Phil
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1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
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Post by Finnpaso »

All output shafts have that 8mm thread, but its useless!

I know, that 4,5" and 5,5" wheels have different carriers and surely need to check chain line, if put 17" wheel to Paso, but i think one possibilty is to use also 907 swingarm and surele again need to check chain line and maybe use different front sprocket. All such time Ducatis have same output shaft, so easy to find "right offset" front sprocket...
Antti http://www.youtube.com/watch?v=HeKOh3XoXPg&NR=1
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Paso 750 -89 red/metal grey
907IE -91 red/metal grey
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front sprocket

Post by ducinthebay »

The countershaft sprocket on my Sport is bolted on using an 8mm bolt into the countershaft, so not so useless for me. The sprocket is basically a stock sprocket for Monster/SS, but has a thick washer welded on. I have seen other Sport sprockets with the similiar arrangement. Since the Sport motor was borrowed from the Paso line, I would assume they are the same.
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.
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Post by Finnpaso »

I havent seen such. (and i am talking about all Pasos, 907IE and ST series Ducatis...) I dont know Sport. Anyway same output shaft all...
Antti http://www.youtube.com/watch?v=HeKOh3XoXPg&NR=1
KTM 990 Adventure -08 metal dark grey
Paso 750 -89 red/metal grey
907IE -91 red/metal grey
907IE -91 red
2xST4S -02 red/metal grey
ST2 -01 red/metal grey
Volvo V70 Bi-Fuel Classic/titanium
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