Aligning triplex sprockets ?

I decided to replace the clutch bearing and figured I'd put in a new triplex chain at the same time. But I don't see a good, positive way to check the alignment of the sprockets. Putting a straight edge against the sprockets doesn't do anything that I can tell because there is no reference surface to base it on. Using the rear chain case as a reference doesn't make sense to me because it may not be perfectly aligned in the first place and I don't know that its construction is square/true with its mounting surface against the crankcase.

The service manual just refers to using shims to ensure correct alignment but they don't explain how to actually check the alignment in the first place. I was thinking of mounting the new chain, leaving out the spacers behind the clutch bearing, tightening the engine sprocket and rotating the engine, and seeing where the clutch sprocket/bearing aligned itself on the shaft. Then, after mounting a dial indicator, move the clutch assy in toward the gearbox and measuring that distance with the Dial indicator to determine the thickness of the necessary shim(s).

Or is that just too complicated for a Commando motor?

So assuming your chain is off, here is where you should align your straight edge.

Aha...so basically the sprockets mounted on the engine/gearbox without the chain, the straight edge is placed across several teeth of the clutch sprocket so it is "square" with those teeth and then, if aligned, the straight edge should just touch the crank sprocket teeth If not, clutch shims are added/subtracted to make it so. Right?

Thanks

It can be done with the inner chaincase in position. I'm inclined to hold the straight edge tight against the engine sprocket as it avoids any movement in the clutch bearing....Of course, you'll have to decide where to position the crank, in terms of its end-float but generally, this is a quick visual check to make sure that nothing's been left out. If it looks right then it is right.

mike996 said:

Aha...so basically the sprockets mounted on the engine/gearbox without the chain, the straight edge is placed across several teeth of the clutch sprocket so it is "square" with those teeth and then, if aligned, the straight edge should just touch the crank sprocket teeth If not, clutch shims are added/subtracted to make it so. Right?

Thanks

Click to expand...

Yes, but also remember, alignment with the gearbox adjuster. Be sure to slacken the drive chain at the wheel as to not cause a restriction and finally re adjust it at the end of the process.
You were more than likely aligned before but now is the time to check it.
Sorry to complicate it.

Thanks goodness the chain is rather tolerant of mis alignment and the fit of crankcase and tanny in cradle pretty much eliminates misalignment. I aim / sim to get clutch as close to the back of case w/o rubbing then all seems to line right up. You can sorta tip trany in cradle intaling it loose but as clamp/bolts nip u the flats self align parallel, If clutch wobbles on its center bearing or deeper in main shaft bushes then measuring by straight edge is a waster of time away from fixing wobble first.

I just handed and tensioned 1' chain yesterday before a ride to find the tanny adjuster had lost its end nut completely and the lock nut backed way away so completely free of holding tranny. For triplex drive I now think the single adjuster is another useless kit - along with Combat cam tabs and small iso doughnuts. I discovered the lost adjuster nut after who knows how many 1000 miles but didn't loose tension or alignment.

It goes by feel and intuition. Use the force young Luke.