Uh-oh!

I removed the primary side today and put it away in it’s own tub. The next I time work on the bike it will be to remove the engine from the frame. What is the best way to do this? I think I remember putting it on a jack lift and removing it like that.

I have a theory about why this failure occurred. If you have been following the saga that is this bike you will remember the last catastrophe. The one in which I dropped an intake valve and destroyed my head and piston on the timing side. I think the piston slamming into that valve compromised the bearing shells which was not apparent to my untrained eyes. After numerous miles after rebuilding it finally took a shit. Opinions?

Larry,
You basically have everything out of the way with the primary gone. Remove the front iso mount and the three bolts holding the engine to the gearbox/swingarm (rear engine mount), and it should slide out on the right hand side. It shouldn't be too heavy without the head and cylinders on.
Edit: I also have to be reminded that yours is a mk3 and I don't own one. LAB will correct me once again if I assume something with a pre mk3 . I've been caught too many times already. but carry on.

CanukNortonNut said:

Larry,
You basically have everything out of the way. Remove the front iso mount and the three bolts holding the engine to the gearbox/swingarm rear engine mount, and it should slide out on the right hand side. It shouldn't be too heavy without the head and cylinders on.

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The bike is currently on the center stand and I am concerned if I don’t have it on the lift when I remove the cradle bolts the bike will hinge.

Jack under the cradle or gearbox.

Gee Larry you not having much luck, I been lucky with my Norton since new and 2 major rebuilds first one building my 850 for the Featherbed frame back in the early 80s first bike I ever built and about 15 years ago replacing the crank cases, the original cases had hairline fractures around the main oil seal and a broken bit on the front of the CC where the front barrel stud threated in, completely broke away and was rolling on top of the crank, it rolled on the top of the crank for about a year before I pulled the barrels off, the broken piece was highly polished lol, young and silly I just Arildite the stud in when it did it, it only rattled when idling when running it floated between the cylinders, was too big to drop down the bottom end lol.
I still have that broken bit in my collection somewhere it broke in the late 80s and after a year before I pulled the barrels I just kept gluing the stud and nut back in for about 20 years, before chasing up another set of crank cases.
But the 2x I rebuilt I replace all bearing and the new set of CC also got new bearing and conrod bearings everytime the bottom end has been pulled down, the super blend bearing were always good when replaced.

Ashley

Larry S said:

The bike is currently on the center stand and I am concerned if I don’t have it on the lift when I remove the cradle bolts the bike will hinge.

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Larry best thing I ever brought for my workshop, well 2 things really was my lift table and the scissor jack for lifting the bike up the scissor jack works so well on the lift table and the Scissor jack was under $100 was a great investment for working on all my bikes.

Larry S said:

I think the piston slamming into that valve compromised the bearing shells which was not apparent to my untrained eyes. After numerous miles after rebuilding it finally took a shit. Opinions?

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The bearings stay where they are from the crush/overstand, if they were hammered by the journal then its possible, as they are only low carbon steel, that the crush was compromised and then they were liable to spinning inside the conrod. The tabs do not stop the spinning which also indicates the low strength of the low carbon steel used for the backing.

Larry S said:

I removed the primary side today and put it away in it’s own tub. The next I time work on the bike it will be to remove the engine from the frame. What is the best way to do this? I think I remember putting it on a jack lift and removing it like that.

I have a theory about why this failure occurred. If you have been following the saga that is this bike you will remember the last catastrophe. The one in which I dropped an intake valve and destroyed my head and piston on the timing side. I think the piston slamming into that valve compromised the bearing shells which was not apparent to my untrained eyes. After numerous miles after rebuilding it finally took a shit. Opinions?

Click to expand...

That was a possibility I was considering.
The wound was too fresh, figured to wait a bit before asking if the lower end was disassembled at the time of the FOD incident.
Define "numerous miles" please.

Larry S said:

The bike is currently on the center stand and I am concerned if I don’t have it on the lift when I remove the cradle bolts the bike will hinge.

Click to expand...

You need to support the frame rails when removing the engine Larry otherwise the whole plot will collapse !

concours said:

That was a possibility I was considering.
The wound was too fresh, figured to wait a bit before asking if the lower end was disassembled at the time of the FOD incident.
Define "numerous miles" please.

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Numerous miles = 1605 mi and no, the lower end was not disassembled.

Larry S said:

Numerous miles = 1605 mi and no, the lower end was not disassembled.

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Thank you. The forensics of failure is valuable.
I hope your crankshaft is ok.
I had good results with: http://www.milehighcranks.com/

If the engine is completely unbolted, and free, you should be able to pick it up, and put it on a bench

baz said:

Really sorry to see this
My guess is it's more than just a big end shell
The piston is too far down for just a shell IMO
I'd check that valve very carefully that the piston kissed
They can easily be very slightly bent

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I worked on a Norton many years ago, not mine. He was having issues with it running. When I removed the head I saw that the LH intake valve was bent. I asked him how fast he was going when he missed a shift. He claimed he hadn't but his girlfriend said yes right when you were passing that truck. Oops! I expect you will need to do a full tear down and inspect everything.
John in Texas

Onder said:

Add the warning buzzer like on the turn indicators...but then most of us won't hear it at road speed anyway I suppose.
You know it may happened that some sludge breaks away and suddenly plugs an oil way or even doesnt plug but finds
it way into the bearing surface and that causes some metal erosion and it just snowballs from there.

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How would any sludge break away? It's being constantly held in place by the centrifugal forces generated by the crank rotation.

SteveBorland said:

How would any sludge break away? It's being constantly held in place by the centrifugal forces generated by the crank rotation.

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True, when the crank is rotating, but when not the sludge might dislodge from gravity

SteveBorland said:

How would any sludge break away? It's being constantly held in place by the centrifugal forces generated by the crank rotation.

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An engine that’s been run for yonks on old school detergent free oil and has swapped over to a modern high detergent oil might.

...I sincerely hope everything in the bottom end (crank etc) turns out alright for you Larry

As now determined.....and its a little late now but......the last paragraph from this comment was crucial advice at that time......The knock on effect......

Larry,
If you can't find a crank grind shop close to you in your area of USA, I can point you to two shops in Ontario Canada that know how to grind a Commando crank.
One is in Listowel, Ideal Supply "napa auto parts" $134.59 Canadian for both throws.
I had two cranks reground -0.010" and less than a week turn around time.

There is another shop in downtown Toronto. The name slips me but I can find it.

I would check your crank for cracks, eg. LP or some means of crack testing Etc. before committing. I would also inspect your Main bearings.
You need to take off the crank center flywheel and then bolt the two cheek halves with the dowel pin included. Pre mark the cheek to flywheel to know the orientation of the flywheel.
A pin prick on the flywheel and one on the cheek on the same side.

I will send you an address if you want to go that route.
Good luck.
Tom
Edit: Correction on Mk3 crank bolts. You have a Crank shaft Dowel Stud instead of a Dowel pin for earlier Commandos. https://andover-norton.co.uk/en/shop-details/16605/crankshaft-dowel-stud

CanukNortonNut said:

Larry,
If you can't find a crank grind shop close to you in your area of USA, I can point you to two shops in Ontario Canada that know how to grind a Commando crank.
One is in Listowel, Ideal Supply "napa auto parts" $134.59 Canadian for both throws.
I had two cranks reground -0.010" and less than a week turn around time.

There is another shop in downtown Toronto. The name slips me but I can find it.

I would check your crank for cracks, eg. LP or some means of crack testing Etc. before committing. I would also inspect your Main bearings.
You need to take off the crank center flywheel and then bolt the two cheek halves with the dowel pin included. Pre mark the cheek to flywheel to know the orientation of the flywheel.
A pin prick on the flywheel and one on the cheek on the same side.

I will send you an address if you want to go that route.
Good luck.
Tom
Edit: Correction on Mk3 crank bolts. You have a Crank shaft Dowel Stud instead of a Dowel pin for earlier Commandos. https://andover-norton.co.uk/en/shop-details/16605/crankshaft-dowel-stud

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Gord Bush Performance Etobicoke ?
He gets all my machining work .

Thanks to everyone for their support and help. I removed the engine today, it was easier than expected. I'm gonna need lots more help in the near future to get this bike repaired properly.