High speed vibbbbrations: rear chain drive sprocket nut off

[51Hog]

Had the tranny rear chain drive sprocket nut come completely off----The washer tabs were never bent to safety the nut. Need to have a talk with the wannabe mechanic that did that!!! Problem is that it was ME--

I ran the bike with the outer primary cover off and noticed that the primary chain was flopping pretty bad.
I checked the tension, and it had about the recommended 1/2 to 5/8 inch deflection. When I turn the sprockets 180 degrees, the chain only has about 1/8 max deflection.
While running the engine and watching the sprockets spinning, It looks like they are running true. It does not appear that the shafts are bent.
Am I correct in assuming that a worn out primary chain could be the culprit? Maybe worn more in one area than the other?
The front primary sprocket is new.
The clutch basket sprocket is old but the teeth look great. Do the valleys in the sprockets usually wear evenly?
Any Ideas?

If I lay the chain on the bench and flex it to the side, there is about1/2 to 3/4 inch deflection in the center.

[Jack_Hester]

51Hog -

A stretched primary will rattle your teeth out of their sockets. They are very hard to stretch, with proper lubrication. But, it can happen. I had to put one on the 59 FLH, a few years ago. It was on the bike, when I bought it in 74. In good shape, at the time. Finally nailed it down as being the source of major vibration, too. They last a long time. Buy good. Buy the best available. Be generous with the chain oiler (though, don't go overboard), and lock that final drive sprocket down this time. That could have been deadly. Drive safe.

Jack

[Cotten]

"Never does only one thing go wrong at a time"....Ridnick Wysdom

Certainly your chain has stretched, but please consider the cause(s).

Do not assume that your sprockets are concentric. It would be incredible if they were!

The motor sprocket is economical to replace, however the clutchbasket is dear for an OEM, and questionable for generic repops.
Yet you have few choices, however.
Replace all, if you can.

PS: Them silly locktabs are a will o' the wisp against the forces of a tired assembly. That's just all they had.
Loctite is a blessing the designers could only have dream't of.

[51Hog]

Thanks for the replies,

Well, Since the front sprocket is new, then I am going to assume that the problem is in either the chain or the basket. Think I will start with the chain.
Which brand chain should I be looking for, and how much should I expect to spend on it?

[Cotten]

Again I caution against assuming that the clutchbasket sprocket is concentric. Please inspect it with a dial indicator upon the valleys of the teeth at various points around the circumference. I have no specs to follow, but a variance of more than .090" would be problematic, IMHO.

As far as brands, I cannot remember any sources of Duckworths in modern history, but would appreciate any leads.
Diamond brand may be all that is commonly available, but I strongly suggest that all Diamond chain products be completely washed out and properly re-lubed before installation.

[51Hog]

Thanks Cotten,
I will check with a dial ind. and cleaning and lubing the chain sounds like a good precaution.
Do you know off hand if a later model basket with a ring gear will fit into my 51 primary case and work with the rest of my clutch assy?

[Cotten]

I asume you mean with the ring gear removed, right?

Otherwise, I think it is nearly identical.

[51Hog]

Aug 16, 2005, 1:33am, Cotten wrote:
I asume you mean with the ring gear removed, right?

Otherwise, I think it is nearly identical.

I don't necessarily want a ring gear 'cause I will never even consider an electric start on this bike, but I have a problem destroying a perfectly good part.
I should look for someone that wants to swap.
If I cant find anyone willing to swap, then I will probably turn the ring gear off with the lathe if it won't fit in the case with it on.

[haggis]

Cotten,
Good , sound, advice regarding washing those Diamond chains out CLEAN....they make one hell of a sticky moosecum mess if you dont! Haggis

[51Hog]

Well,
I just finished putting in a new Diamond Primary chain, New front sprocket, and I took the starter ring gear off a later model clutch basket and installed it in the 51. (It does fit nicely)

None of these replacements cured the uneven slop in the primary chain.
I marked the crank pin gear at the tight point on the chain, Spun the engine 180* and the chain had 3/4" slop at that point.
The crank pin appears to be bent.
I still have not brought the dial indicator home to check for certain, but all leads point to the crank pin.
Can flywheel alignment cause this?
Does the taper normally go bad in the flywheels or crank pins?
Is it a common occurrence for a crank pin to bend?
Any input?
Thanks.

[Cotten]

Since the 'crank pin' term applies to the rod journal, should we assume you really mean the sprocket shaft?

Yes, they can bend.

A bent sprocket shaft or tranny mainshaft can have minor effects, but I still suspect your sprockets.

[51Hog]

You are right, I am talking about the sprocket shaft.
I sometimes get confused. I will check with a dial indicator.
I lean towards the shafts because of the new front sprocket, the new chain, and the second used basket. The before and after have the same effect on the chain. Tight and loose 180* apart on the sprocket shaft gear. If it were the basket gear or the tranny shaft, the chain would be tight and loose when that gear moved 180*.

Thanks