Discussion in 'Norton Commando Motorcycles (Classic)' started by swooshdave, Aug 17, 2018.
Repair? WTF? Can cases go in the recycling bin with beer cans?
Well that’s were I’d put them.
But others differ.
Just curious as to Swoosh’s plans.
I've seen cases repaired quite nicely by competent, experienced (same thing?) welders.
The crank may be another story. Looks like a big divot in the drive side cheek, likely have to AT LEAST statically re-balance after the repairs...
I didn't see where you mentioned it, but did you set your crank end play before you put the rods in place? Easier that way.
What do you mean?
I'm going to replace AND repair. You've seen the replacement bottom end. Once the broken case comes out it will go to Master Comstock for evaluation and hopefully repair. Then rebuild it back up.
I'm just praying that the barrel and head are salvageable.
I bought a set of really, really nice Combat cases to use as a donor for the repair but it guts me to have them hacked apart. But I will to save the serial number on my cases. So if anyone has a left side case that could be used to patch it I'd appreciate it.
Hi Dave, you have experienced a blown motor which threw a rod and in the process probably damaged the crankshaft and destroyed the crankcases. By the looks of it due to oil starvation or material fatigue. Now you're rebuilding another using similar old parts of unknown history? I woudn't do that if I were you. Carillo rods, a steel flywheel and a new or rebuilt oil pump is the very least I would fit, especially since this is to become a Combat engine. I would also consider fitting a new through-stud barrel to get rid of another structurally weak spot.
Well, one theory is to overbuild a motor. But then again, the original motors lasted for 50 years. It depends on how you abuse them. I don't race and I don't race on the street. It was just an unfortunate incident. Otherwise the engine would have lasted for tens of thousands of more miles.
As noted the replacement engine will just be used until the original is rebuilt. Every indication is that it was a very low miles engine, there was low wear everywhere I looked. I'm not concerned about it at all.
And it if fails, oh, well. I don't have a ton invested in it.
Set the crank and new rods in the empty cases, nip up the case bolts, then measure crank end float and shim to spec. Easier taking the crank out to shim it BEFORE installing the rods.
I would like to remind of Minor-Palmgren's simple cumulative damage theory:
D = 1 - n/N
where D = 0 represents 0 remaining life (100% of the components fatigue life consumed) and D = 1 is as new. N is the fatigue endurance at each load step and n the number of actual cycles at this load step. The delivered power and load over an engine's lifetime is devided in steps according to various models, one of which is the so-called "rainfall" method.
Estimation of fatigue life consumption assumes you know the history of the component. If you don't know, well ......
Of course there can be other causes of malfunction, oil starvation for instance. Monitoring is as important for old engines as it is for new ones, probably even more so.
Now you tell me!
I don’t do math.
Thanks to @Mike T for the Norton banner!
When we last left off the next thing to come off was the front pulley. I picked up the 5/16-24 bolts from Home Depot and they worked great. I didn't have to turn the puller a full turn and the pulley popped off. This was the same puller I used on the main bearing on the other engine. The puller has more than paid for itself.
After taking a few more things off (everything come off easier than I thought. The toughest fight was the manifold bolts but they are never easy.
And finally we can get a better look at the hole.
I think I've finally solved the wetsumping problem!
Everything that could be was just pulled to the side. Maybe it will go back together easier too?
Since it all has to come apart I think I'll pull the head, then the engine.
I could only imagine the words out of your mouth when that happened!
It is too bad that we can't buy just more jaws for the puller. I think we need to talk to AN about that.
bummer just the same. You really need to make the outer ring nut as snug as can be with no misalignment behind the gear.[/QUOTE]
So that everyone knows you actually CAN buy just the jaws!
Look on the bright side if you have to buy another puller at least you'll have two spare teeth . Okay I get my coat.
Broke my first pinion jaw the 2nd time I used it, bought 3 spare teeth and never had to replace another one since...
As per the post on Facebook, it looks much the same as the hole on mine.
Mine has been successfully welded although I've no pics as its still with my mate for further finishing.
Do you know how it was welded, particularly how warping was overcome? When aluminum castings are welded, a lot of residual stresses are built in due to the rapid cooling of the material. These may have to be releaved by post-weld heat treatment, but I doubt PWHT will prevent defomations. I tried welding a cracked slider once. The slider ovalised severely and now graces my workshop. I am happy for you if you can make the crankcase fit for service again.
I think sliders are tougher because they are one piece and smaller.