Norton Commando Crankshaft bodge up.

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This went so well, why not post it.
I have never been backward in coming forward when it comes to taking the easy option, that would be the make it as easy as possible even if you have to make a few items to do so.

First was to make a short arm extension which was made for my 1973 Moto Guzzi gear shift linkage but a bit of a failure as far as having play.
Duly modified and relives as a Norton tool.
Easy step one, just torque the fasteners, seems straight forward.

arm1.jpg


ex.jpg


arm6.jpg


46 or so years old and good for another round after polishing.
Wear and roundness is all but as the day it left the factory, nil. (Perhaps mid week or pay day)

j.jpg

Forget the dial gauges.
crk.jpg


It came up very nice and ready to go.
 

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Next obstacle.
The shiny crankshaft has 0.8 mm / 0.032" end float when the spec is suggested at around 0.010" to 0.015" after a check with dummy bearings.

brg.jpg
 

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Shims are not easily available and only Old Britts do them that I know of but do not do International post these days.
That means make them for the easy option by machining a jig to do so out of stainless steel shim sheet.

OD.

s4.jpg


ID.

s2.jpg


OD on the flat side of the jig main body.

s8.jpg

ID on the counterbored side.

s7.jpg
 

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Bake those cases.

s9.jpg


Centre that shim.

s55.jpg


Place that drop in bearing carefully and add a weight until it has cooled down.

s44.jpg


Some time later assemble in the cases and check the end float.
0.25 mm shims x 2 almost hit the mark. (End float checked at 4 positions of rotation)
I will allow 0.001" for the Wellseal or somewhere around the middle of the spec end result.

dl1.jpg


The end.
 

APRRSV

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Bake those cases.

View attachment 19430

Centre that shim.

View attachment 19432

Place that drop in bearing carefully and add a weight until it has cooled down.

View attachment 19431

Some time later assemble in the cases and check the end float.
0.25 mm shims x 2 almost hit the mark. (End float checked at 4 positions of rotation)
I will allow 0.001" for the Wellseal or somewhere around the middle of the spec end result.

View attachment 19429

The end.
Hi TW,
I note that your con rod journals appear to have a mirror finish. Is that the result of a regrind or polishing effort?
I'm interested because I'm at about the same stage with my crankshaft and about ready to send it out for dynamic balancing. My stock journals are no where near as pretty. Wonder how you got yours that way and whether I should polish mine. I worry about taking too much off and having undersize journals.

Thanks,
Ed
 

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I do what used to be called shoestring polishing but use towel strips these days.
If anything the journal will be clean but being done by hand any diameter reduction would be nil or take a very long time if so.
I think it is more a cosmetic thing and need cleaning well afterward (I use Acetone and then lint free cloth with oil)

This was the re ground crankshaft out of my 1973 Moto Guzzi.
It got the oil holes chamfered, polished as above and (dynamic) balanced it at home with 177 grams of Mallory metal slugs to suit 88 mm pistons.

1_2.jpg

Same with the rod bolts.
thumbnail_Image-59.jpg

The only drill on the planet it seems that would go through were ARTU / USA made.

thumbnail_file-13.jpg


I will start on the Norton IWIS Duplex primary conversion tomorrow including moving the charging system inboard once the primary sprocket is reduced (to duplex as will the clutch basket)
 
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Those primary sprockets are hard, to thin mine to allow a starter sprag to be added I resorted to grinding.
 

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I do what used to be called shoestring polishing but use towel strips these days.
If anything the journal will be clean but being done by hand any diameter reduction would be nil or take a very long time if so.
I think it is more a cosmetic thing and need cleaning well afterward (I use Acetone and then lint free cloth with oil)

This was the re ground crankshaft out of my 1973 Moto Guzzi.
It got the oil holes chamfered, polished as above and (dynamic) balanced it at home with 177 grams of Mallory metal slugs to suit 88 mm pistons.

View attachment 19459
Same with the rod bolts.
View attachment 19460
The only drill on the planet it seems that would go through were ARTU / USA made.

View attachment 19461

I will start on the Norton IWIS Duplex primary conversion tomorrow including moving the charging system inboard once the primary sprocket is reduced (to duplex as will the clutch basket)
Hi TW,
I have never heard of shoestring polishing. Can you tell me a little more about how you do it with cloth strips? I.e. any particular type of cloth (microfiber, cut up clothing etc.) and whether it is just the cloth or with lubricant or abrasive?

Thanks again,
Ed
 

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I use towel strips maybe 20/25 mm wide (1") folded over and Autosol, they will polish once black.

This is a set of rods, no power tools or any form of polish compound or paste.
Perhaps 2+ hours each rod until ready to use, rod, caps and bolts.
I can not think of any item that is usable as is including brand new parts (which normally need the most attention)

Rod1.jpg
 

Dommie Nator

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What's the consensus of opinion here on which direction the crank journals should be polished?
For example some 'experts' say grind opposite of working conrod travel then polish with working travel. Some others say it doesn't matter. I polished mine with travel but I didn't have a clue which way round they were ground.
 

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I use towel strips maybe 20/25 mm wide (1") folded over and Autosol, they will polish once black.

This is a set of rods, no power tools or any form of polish compound or paste.
Perhaps 2+ hours each rod until ready to use, rod, caps and bolts.
I can not think of any item that is usable as is including brand new parts (which normally need the most attention)

View attachment 19581
I do what used to be called shoestring polishing but use towel strips these days.
If anything the journal will be clean but being done by hand any diameter reduction would be nil or take a very long time if so.
I think it is more a cosmetic thing and need cleaning well afterward (I use Acetone and then lint free cloth with oil)

This was the re ground crankshaft out of my 1973 Moto Guzzi.
It got the oil holes chamfered, polished as above and (dynamic) balanced it at home with 177 grams of Mallory metal slugs to suit 88 mm pistons.

View attachment 19459
Same with the rod bolts.
View attachment 19460
The only drill on the planet it seems that would go through were ARTU / USA made.

View attachment 19461

I will start on the Norton IWIS Duplex primary conversion tomorrow including moving the charging system inboard once the primary sprocket is reduced (to duplex as will the clutch basket)
Hi TW,
After some thought, I wonder if there is no "wearing in" type mechanism needed for rod bearings and rods similar to new rings with non-polished cylinder walls. What are your thoughts?

Thanks,
Ed
 

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Ed, Ideally the bearing surface will not come into any friction loaded contact with the crankshaft journal ever.
There would be nothing to bed in with those parts.

I personally use Suzuki branded Moly paste on a lot of parts to minimise friction at start up even with the system oil primed.
One reason I make sure everything is clean is, anything in a oil passage will go straight to the rod bearing long before it see's the oil filter and that includes engines with a filter on the pressure side.

This was a new billet rear bearing that I fit to my Moto Guzzi but after I deburred it (CNC machined bearing)

Looks shiny.
thumbnail_Image-43.jpg


There were plenty of others.
You can see all the rag around the oil feed hole, waiting unless removed before installation.

thumbnail_Image-49.jpg


My first ride on a Commando was the late 1970's but it is a bit hazy now, it might have been 1980 when my daily ride was a 1974 Kawasaki 750 H2B (which I kept)
I was offered a ride on a freshly restored '750 Combat not that I knew what a Combat was, it was OK but not enough to buy one.

My recollections of Commando's was, they blew up or more precisely threw connecting rods.
Another mate had a Combat and recall some time in the late 1980's we set off on what might have been a 2000 to 4000 km trip (I had my first bevel drive 900 Ducati by then (which I kept also)

He flatted in a house that backed onto the motorway so we had to go a short distance north to an on ramp then south again, any thoughts of 'born to be wild were soon a few second memory as it blew a head gasket near level with the house we had just left.
I remember annealing a replacement head gasket for him.

We rescheduled the departure date but the following week it threw a connecting rod all but destroying the engine.
I remember another mate I rode with had bought a Commando brand new, when I said I was looking for a Commando he frowned some and he was a fairly hard core Norton guy.......... who went to Japanese bikes.

The point, the crankshaft must rotate smoothly and be happy to do so, the other bits need to be happy going up and down and there must be a clean and reliable supply of oil to the connecting rod bearings which is why nothing (to me) is to much trouble in that quest.

Rods.jpg


I will machine an oil pressure gauge (Marlin's/USA) mount that will attach under the top triple clamp considering a pressure gauge non optional.
Just to complicate it a bit there will be no hose going to the gauge directly, the oil will flow through the mount itself.

Oil, oil pressure confirmed and all should be good.

Most melt downs show the shell has tried to weld itself to the journal when oil supply is lost. (worst case at speed)
If you are then more unlucky the shell will try to spin inside the rod big end and something will fail, the rod, maybe a rod bolt.
If there is a reliable oil wedge and bearing clearance that is unlikely to happen.

This is a shiny on the inside bike, as is on the outside.
 

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What's the consensus of opinion here on which direction the crank journals should be polished?
For example some 'experts' say grind opposite of working conrod travel then polish with working travel. Some others say it doesn't matter. I polished mine with travel but I didn't have a clue which way round they were ground.

 

Dommie Nator

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One way to achieve the proper surface finish on cranks and cam journals is to grind them in the opposite direction they normally rotate in the engine. Most automotive cranks typically rotate clockwise, but some industrial and marine engines rotate counter clockwise. So you have to know which way the engine rotates before you mount it in the polishing stand.

Polishing the crank or cam in the opposite direction it was ground will also break off more of these ferrite burrs, leaving a cleaner smoother finish as well. Ferrite burrs, if not removed, can cause problems later on because they can wipe away the oil film and cause a bearing failure.

Not all engine builders agree this is necessary, but it should remove the sharp edges of the ferrite burrs leftover from the grinding process and leave what is called a "favorable" finish.

One rebuilder we spoke with says he grinds one direction and polishes the other to get as smooth of surface as possible.


I was wondering what our "Access Norton" engine "experts" opinions were.
 
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Fast Eddie

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My approach has generally been thus: take to grinders, pick up, fit, thrash.

This thread has made me feel woefully inadequate. Again.
 
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I use towel strips maybe 20/25 mm wide (1") folded over and Autosol, they will polish once black.

This is a set of rods, no power tools or any form of polish compound or paste.
Perhaps 2+ hours each rod until ready to use, rod, caps and bolts.
I can not think of any item that is usable as is including brand new parts (which normally need the most attention)

View attachment 19581
I usually keep the bearing caps with their own con-rods and never swap their direction of fit.
 

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A good thing I marked them then.

AE pistons and rings, maybe an hour each to prep out of the box.
The new bolts took around an hour to fit/seat, they are an odd construction to say the least.
Why they have a smaller OD head than stock bolts but a larger eccentric is beyond me.
People familiar will know what to check especially with the larger fillet radius.

piston.jpg


The engine case joint prep had been done long ago when I machined the inner dam to clear the reed valve inlet tube.
All threaded holes countersunk so any possible pulled thread would not effect the mating surfaces.
Any drilled holes the same.
Those surfaces lap checked with a ground square bar and abrasive, all it takes is a small riser to stop the cases seating and even on very nice cases it is not unusual to lap test them and find shiny rings (high spots) around all holes.
The sealer then has a much easier job especially once at operating temperature. (imho)
There is no reason for leaks.

The joint prep was after this.

IMG_4641 - Copy.JPG
 
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