Big end tolerance

[SPRIDDLER]

Deleted - dup of my previous reply.

[KerryAJS]

Thank Spriddler..wise words!
@ Joker-Bones, interesting point, I would imagine the 1 thou' oversize would be shared over 4 rollers ? As my 1+ thou' of play is a combined push and pull measurement. I would have thought the Army Spec's book 3 thou' Condemnation limit would also have been an overall push/pull measurement.. but I'm guessing here.

[KerryAJS]

I wish I didn't have to change the axle Spriddler, but before I pulled off the timing gear I noticed 4 little lines on the end of the thread, (Zoom in on the photo') which turned out to be cracks!! 40+ years ago I would have welded it up, re-threaded and center drilled etc, as we wouldn't have been able to get the part or it would have taken too long!

[Les Howard]

Hi Spriddler, yes it's probably something you might not have bothered to note at the time...

[SPRIDDLER]

I wish I didn't have to change the axle Spriddler, but before I pulled off the timing gear I noticed 4 little lines on the end of the thread, (Zoom in on the photo') which turned out to be cracks!!

Errm, well that's not unusual and probably caused by a PO when using a puller to remove the pinion as they sometimes require a fair bit of force. How far along do the cracks extend?

Purists look away now as the following contains information that may cause offence.............

If it (probably) has been running like that for some while I'd be inclined to continue with it.
Once the keyed pinion and nut are in place it's unlikely to get worse as it was use of a puller that caused it not stress when the engine was running.

[KerryAJS]

Apologises Spriddler for the late reply, life got in the way again!
On closer examination the axle is fractured/split back a few thread on all 4 lines. In another time I would have tacked it back together and retreaded it, after buying a left handed split die!
Now that I have time, I'd like to replace the axle, that is if the quality of the new one is OK? Splitting the flywheels will give me chance to look at the crankpin bearing.

[KerryAJS]

I think it looks OK?
Just a bit of Rubbing/Staining on the Liner, no wear with the finger nail test and the bearings look OK too... what do you think?
Leave well alone!!

[Joker_Bones]

I have no experience of rebuilding the big end on a single so wouldn't offer advice.
My first thought was that I would be curious to measure the dia. of the rollers.
But then then thought if you intend to reuse them I wouldn't want to disturb their position/orientation.

[SPRIDDLER]

On closer examination the axle is fractured/split back a few thread on all 4 lines. In another time I would have tacked it back together and retreaded it, after buying a left handed split die!
Now that I have time, I'd like to replace the axle, that is if the quality of the new one is OK?

Now that you've mentioned the extent of the cracking and done the hard bit - splitting the flywheels - I would replace the axle.
I can't comment first-hand on the quality of a replacement but I do know that the club goes to great lengths to ensure that the original factory spec'n is followed for spares wrt material, dimensions and finishing processes.
There's little worse when on a long trip than having the nagging feeling of doubt about what you wish you had replaced.
(My hands-on experience is only up to mid 50's and it may not apply to your '63 but I'll mention the obvious anyway (before it's too late?) insofar that the axle must be accurately oriented in the flywheel to align the oilway).

Re the big end......

I think it looks OK?
Just a bit of Rubbing/Staining on the Liner, no wear with the finger nail test and the bearings look OK too... what do you think?
Leave well alone!!

It's difficult to be certain without being able to feel the wear (i.e. for roughness, cracked roller etc) when it was assembled and you haven't shown the crankpin bearing surface but the conrod liner seems to be O.K. Probably worth checking the liner for ovality. Since you said there's only a thou wear in the assembled big end I wouldn't replace it (unless I needed to hide c. 300 quid and the missus is browsing the IKEA catalogue).

[Ralph]

If all else in the garden is rosy, if new standard rollers are not to expensive I would be tempted to fit a set of them.