A10 engine metal xmas tree decorations (shims)

[Macbeth]

So ive prob done 200klm on the bike since I bought it, its always had ample oil & big solid flow as im getting used to the bike & watching it like a hawk on every start. Oil looked that typical old oil so I decided to change it this morning

There is no engine knock, bit of valve noise which can be louder on start but the engine is faultless to ride. It looks like a Shim to me, its a spring steel & very thin. Any ideas ?

[RichardL]

No question. Those are pieces of crankshaft end float shims. Complete strip down and rebuild everything that needs it forthcoming.

Richard L.

[Macbeth]

No question. Those are pieces of crankshaft end float shims. Complete strip down and rebuild everything that needs it forthcoming.

Richard L.

Cheers Richard, what's likely caused it ? Age & wear/tear ?

I always ready myself for issues on buying a new bike & looks like ive caught one in the nads here. If anyone knows someone in Brisbane whom they recommend for a big repair pls let me know

[limeyrob]

Its caused by the drive nut coming loose and no longer pushing the inner race of the roller onto the shims.  The inner race can start to spin and that destroys the shims.
You will find the DS bearing may be a sliding fit on the shaft, that's OK with locktite so long as there's no play.
I'm rebuilding a bottom end that has had this happen and I've had to modify a shim to sit in the wear groove in the crank web before i can then add shims for the end float.
The drive nut should be 67lb-ft and have a tab washer, many are nothing like tight enough.
SRM do a hex nut conversion that makes it easier to get the torque right.
Also check for a wear step on the crank drive splines, this may catch the drive on the splines and not fully push on the shims.  I've just been stoning the splines to smooth out just such a step.

[Macbeth]

It’s caused by the drive nut coming loose and no longer pushing the inner race of the roller onto the shims. 

Champion mate 👍 Appreciate that info & some hope of a not so expensive fix.

[RichardL]

As Rob says and adding that the loose nut allows the lobes of the cush drive to increase the sideways movements of the crankshaft, putting more forces on the shims and inner race. 

At one time, I would have suggested reaching out to our member “Dutch” (in Brisbane) but he went silent a while back.  Others here (more local than Chicago, Illinois) may have Brisbane contacts, otherwise, you might ask Dave Kellett Motorcycle Engineering to steer you to someone. (Long story how I know of them.) Another option is to do it yourself, if you’re mechanically inclined. These are not highly sophisticated machines and you can get all the advice you want here on the forum (some from actual experts).

Richard L.

[limeyrob]

Be sure to fit the tab washer - 65-2521 to stop it undoing, the split pin is a distraction, its just to protect the timing case if it all goes pear-shaped.  Funny I've stripped a few of these engines and don't recall the tab washer so I suspect it gets left out.

[Worty]

Be sure to fit the tab washer - 65-2521 to stop it undoing, the split pin is a distraction, its just to protect the timing case if it all goes pear-shaped.  Funny I've stripped a few of these engines and don't recall the tab washer so I suspect it gets left out.

No tab washer on mine.  Just brute force with a good splash of Loctite and the split pin.  Don't know from memory how a tab washer would fit - onto splines and around the nut

[muskrat]

G'day Mac.
I agree with all replies. Full bottom end rebuild if it were mine. Before you strip it down measure the endfloat with a dial to give you a rough idea of the shims required.
Have a real good look at the t/s bush, crank journals, cam & bushings.
The d/s bearing "should" be a light press fit on the shaft which makes it a bit of a job to trial shim the endfloat. I like to use a bearing with a nylon cage to make it easy to get the bearing off. Heating the bearing in oil on the stove makes it easier to put on the shaft.
If you decide to do the job yourself there is plenty of help here on the forum. I have a mate up there with a machine shop that's been playing with bikes for 50 years if you need any machining done.
Cheers
ps: Worty got in while I was one finger typing. Never used a tab washer, I make a shim washer to go behind the split pin.
 

[KiwiGF]

It’s caused by the drive nut coming loose and no longer pushing the inner race of the roller onto the shims. 

Champion mate 👍 Appreciate that info & some hope of a not so expensive fix.

As per other advice this forum can steer you through doing the whole job yourself. A workshop charging an hourly rate would cost a fair bit, I would guess 8 to 16 hours? (assuming no other issues found). In NZ the labour rate in main dealerships is $130 ph.

A compromise would be to remove the engine from the frame and take just that to a workshop for the crankshaft re-shim job. Preferably remove the head before taking the engine from the frame, and maybe also the barrel as the lower weight makes lifting the engine out easier. You can leave the pistons and magneto in place (and avoid doing the ignition timing).

[limeyrob]

I've just bought the tab washer, it fits on the spline and gets bent over into the cut out in the nut, so you have to bend it through the spring.  I don't ever recall doing this so this will be a first

[chaterlea25]

Hi All,
I wrote a reply earlier but it seems to have gotten lost, no harm as all the relevant advice has been given
My advice is to forget the lockwasher and use loctite on clean metal
My theory is that the lockwasher's are soft while all the other components are hardened, the washer yields over time and pressure from the cush drive action.. leading to the nut loosening
Once loctited I have never seen one come loose, I have done this on quite a number of BSA's over the years


John

[limeyrob]

Its not a bad job and if the shims are busted there's a good chance the bearing is not a tight fit on the shaft so shimming may be relatively easy.

[Worty]

I've just bought the tab washer, it fits on the spline and gets bent over into the cut out in the nut, so you have to bend it through the spring.  I don't ever recall doing this so this will be a first

I'm confused with this.  I had to have 3mm shaved off the spacer to align the engine sprocket with the clutch chainwheel (Bergs and MWAS supervised and machined).  The only concern we had was that the spacer would clear the splines by a few threads so the nut could be belted up against it.  This being the case, where would the tab washer fit over the splines

[Worty]

Hi All,
I wrote a reply earlier but it seems to have gotten lost, no harm as all the relevant advice has been given
My advice is to forget the lockwasher and use loctite on clean metal
My theory is that the lockwasher's are soft while all the other components are hardened, the washer yields over time and pressure from the cush drive action.. leading to the nut loosening
Once loctited I have never seen one come loose, I have done this on quite a number of BSA's over the years


John

This is what I did John.