Sprocket Wear

hobot said:

To convert to ** .240" ** wide teeth "Not" .250" , just buy an Atlas 520 sprocket and have shop mill the DS of teeth off the drum. Most can fit 530 X-ring but not "slightly wider and way stiffer O-ring", w/o clearance issues that matter, some clear completely others chew a bit of a non issue notch in gb or primary case before running silent. Plan for spare teeth on hand if using all the Torque on tap regularly.

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According to my Machinery 's Handbook it should be 0.227" if you want to split hairs.
Here is a good link. No Pun intended. :mrgreen: http://gizmology.net/sprockets.htm
Remove it from the outboard side.

hehe appreciate mostly rational reactions to my seemly irrational posts but annoying you miss my actual words and meanings. Part of my Norton hobby is communicating accurately to others.
Its obvious and all of us wrote right off - some alignment fault caused the DS sprocket wear shown and that answered the subject line question. MIght check and see if anyone beside hobot offered up places to suspect most. So nothing for his problemo but dig in to the bottom and work back out with good parts that allow proper alignment.

Then the 520 side line started. I outlined how simple and to me stupid to do on road bikes, Though it less wise to grind down hardened Cdo sprocket when Atlas sprocket are ready made for this.

Was confused by your comment that left me thinking you were thinking there was some out of the ordinary routine alignment issues with 520. I gave solution to the only concern there is, that to keep chain sprocket in factory designed position/alignment requires tooth narrowing Only on the DS, not TS nor either side equally. Also width is .24" not .25" is all.

Two chains paths to align makes brief posts confusing. Triplex chain is pretty darn well aligned by setting gearbox square in the cradle. I have my doubts that any device can significantly improve on this simple method which can be finer tuned by some bluing on the sprocket sides to witness undo uneven rubbing. A belt staying on w/o guides is done by trail error. I dare ya to try a run away from home or down the track with a belt, going only by crude fuzzy laser spots or string or fumbled straight edge. if ya want to do it optically nothing beats getting glass panes parallel in the from of mirrors with scribe marks.

I get good drive chain alignment to the aligned primary by sticking fingers bewix tire and swing arm legs. Realized this after successfully trying out the above gizmo's to get another headache smacking my hollow brain case.

So worse clutch loose, main shaft, counter sprocket, wobble misalignment source I've ever found was the dang sleeve shaft bushes, not the bearings, not the shafts, not the rear wheel hub. I put in three plus oil grooved em and ran AFT non Type F to extend the non rubbing state of chain on teeth. You know those sleeve bushes do not - can not get any lube in heat removal out when in lower gears, so I suspect this instant sprocket wear issue stemmed from someone like me enjoying Norton torque too long in lower gears. Hope this wraps it up but still leaves space for final belt drive examples...

Dances with Shrapnel said:

CanukNortonNut said:

.....if you have a machinist buddy you can do it yourself..........the other side is ok then lathe this side down.

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The countershaft sprocket is hardened so it will take some extra measures to shave it down from 530 to 520; either special cutting tools or grinding. Although I have done this for Vintage race applications, this was done "in-house"only to get the chain offset I wanted. For street applications I would go with off the shelf. This will start you off with a nice fresh tooth profile.

As stated elsewhere above, bin the old chain and replace the rear sprocket if questionable.

O-ring chain is the cats pajamas but I don't know about potential clearance issues, other may be able to elaborate on that. At the risk of stating the obvious, with o-ring chain, the lubrication and maintenance is a but different than OEM chain.

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Hey Dances
You may have a problem if all you have is HHS cutting tools on your tool post of a lathe but today’s carbide insert selections can peel the hardest steels. I used ceramic inserts to peel off hardened D2 rolls from a forming mill. It came off red hot in a continuous ribbon. That stuff was hard. But the sprockets should be a piece of cake.
Regards,
CNN

If I'm not mistaken, alignment issue could be from a tweaked swing arm.
Has the swing arm been rubbing on the primary case.
Looks like the swing arm pivot end is real polished.
Show us the backside of the inner primary cover.
Has the bike been layed down?
Mine was rubbing prior to having the frame straightened and now has a 1/4" clearance.
My sprockets looked just like yours but are now in alignment.
Look at the alignment of my swing arm.
Before you start aligning things you might check to see if everything is straight first.

Guido said:

If I'm not mistaken, alignment issue could be from a tweaked swing arm.
Has the swing arm been rubbing on the primary case.
Looks like the swing arm pivot end is real polished.
Show us the backside of the inner primary cover.
Has the bike been layed down?
Mine was rubbing prior to having the frame straightened and now has a 1/4" clearance.
My sprockets looked just like yours but are now in alignment.
Look at the alignment of my swing arm.
Before you start aligning things you might check to see if everything is straight first.

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Guido
When I see rub marks on the inside of the primary and a groove from the chain digging into the primary case oil seal disk the first thing that I look for is where that gear box top bolt spacer is. :shock: I have seen too many Commandos where this spacer is either not there or is placed on the outside of the engine/ gearbox mount. With out that spacer in the correct location by tightening up the gearbox top bolt it pulls the engine mount towards the inboard, which pulls the primary case inboard and mashes it up against the swing arm end cap.
CNN

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CanukNortonNut said:

Hey Dances
You may have a problem if all you have is HHS cutting tools on your tool post of a lathe but today’s carbide insert selections can peel the hardest steels. I used ceramic inserts to peel off hardened D2 rolls from a forming mill. It came off red hot in a continuous ribbon. That stuff was hard. But the sprockets should be a piece of cake.
Regards,
CNN

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Yep, not saying it cannot be done but they are hard and an ordinary cutting tool is not up to the task. I seem to recall my machinest referring to something even more tenacious than carbide but I leave this to the machinest. Just a good heads up for anybody that wants to undertake this task.

Guido said:

If I'm not mistaken, alignment issue could be from a tweaked swing arm.
Has the swing arm been rubbing on the primary case.
Looks like the swing arm pivot end is real polished.
Show us the backside of the inner primary cover.
Has the bike been layed down?
Mine was rubbing prior to having the frame straightened and now has a 1/4" clearance.
My sprockets looked just like yours but are now in alignment.
Look at the alignment of my swing arm.
Before you start aligning things you might check to see if everything is straight first.

Click to expand...

The bike's been down, but not by my hand. There was some minor damage on the right header, right switch housing and MC cap when I acquired it

The swing arm and possibly the chain has been rubbing on the inner primary case, here's a pic. I'll check for the gearbox top bolt spacer

[ATTACH=full]87762[/ATTACH] [url=http://www.flickr.com/photos/52577093@N03/7283356418/]IMG_6044 by niagaraz, on Flickr[/url]

Guido said:

If I'm not mistaken, alignment issue could be from a tweaked swing arm.
Has the swing arm been rubbing on the primary case.
Looks like the swing arm pivot end is real polished.
Show us the backside of the inner primary cover.
Has the bike been layed down?
Mine was rubbing prior to having the frame straightened and now has a 1/4" clearance.
My sprockets looked just like yours but are now in alignment.
Look at the alignment of my swing arm.
Before you start aligning things you might check to see if everything is straight first.

Click to expand...

The bike's been down, but not by my hand. There was some minor damage on the right header, right switch housing and MC cap when I acquired it

The swing arm and possibly the chain has been rubbing on the inner primary case, here's a pic. I'll check for the gearbox top bolt spacer

[ATTACH=full]87763[/ATTACH] [url=http://www.flickr.com/photos/52577093@N03/7283356418/]IMG_6044 by niagaraz, on Flickr[/url]

Hm must add bent swing arm to list of missaligners. Sprocket somehow seem projected too far into inner case, only thing I can think might do that is spacers behind the sprocket of TS main shaft nut backed off to left it shift outward when loaded. Well another thing comes to mind on the primary case, it could of been deflected inward by its mounting faults, but that would not account for the sprocket wear on the side shown. One possible positive benefit of the chewed case, should clear a 530 X-ring chain now.

Not the best pic of the Gearbox Top Bolt Spacer. It appears to be in the right place?


[ATTACH=full]87764[/ATTACH] [url=http://www.flickr.com/photos/52577093@N03/7283544548/]IMG_6045 by niagaraz, on Flickr[/url]

To check for a tweaked swing arm, lay the swing arm on a flat table, place a rod thru the bushings and thru the axle slots and see how parallel they are and also if all four points are in contact with the table as seen in my picture.
The bike may have been layed down at some point and if so then the frame should be checked out too which would contribute to the whole misalignment thing because if the swing arm is bent, which is a real rigid part, the frame which isn't could surely have moved out of spec.
Mine was out by a 1/4" and now fixed there is a 1/4" of space between the swing arm and the primary case. It was the best $520 I ever spent.

Well, the Gearbox Top Bolt spacer is there, but the Gearbox Pivot Stud washer appears to be is missing. Not sure how thick it is but probably a good place to start. Probably will end up pulling the gearbox and check the mountings

What role does the clutch location spacer play? (Section 10, item 54) Are there any shims that go between the inner case and the countershaft sprocket to
[ATTACH=full]87765[/ATTACH] [url=http://www.flickr.com/photos/52577093@N03/7287509282/]IMG_6048 by niagaraz, on Flickr[/url]

One, don't over torque kill yourself on nipping up the big ole sprocket nut it don't get much shear-side trust loads and nailed down well by innate design. No shims are used behind the sprocket. The clutch locator is a fixed dimension spacer that helps protect against over tightening the clutch nut. Missing it would cause basket to wear away the inside of the case not the back side. The same if clutch nut over came the small circlip to shear past its seating stop- as very easy to do. Its possible there was an over tightened triplex chain event that pulled the gear box out of line and could show up as wear on side shown here.
If so better check crank run out and gear shafts for candy cane-ness.

The clutch location spacer shoulders up against and constrains the circlip you see in the picture. It fixes the alignment of the clutch basket sprocket to the engine sprocket. There may or may not be additional shims. Shim as needed to get proper alignment of the clutch basket sprocket with the engine sprocket.

Suggest replacing the circlip while you are there. Overtightening of the clutch hub nut sometimes leads to shearing of the circlip.

Ok , lets see if I have my head around the alignment options of the clutch inner case and counter sprocket.

- the clutch hub and clutch sprocket are aligned to the engine sprocket using clutch hub spacer and shims (there were 2 shims on disassembly one thin, the other thicker). The clutch fixing nut bolts on the mainshaft and torques against the hub, shims and spacer and is backstopped by that tiny circlip. (I now understand the overtighning cautions). The Inner Case 'floats' on its seals over the end of the sleeve gear but isn't fastened to the mainshaft or sleevegear. The inner case is held by the 3 chaincase fixing bolts to the crank case and supported by the chaincase centre

- the countershaft sprocket is fixed by the splines on the sleeve gear. The spacer on the gearbox top bolt and washer on the gearbox pivot bolt set the proper left/right alignment of the gearbox

Inner Case Alignment Options
- make sure correct gearbox spacers and washers are in place
- add shims the crankcase centre stub to provide additional clearance
- check for bent frame and swing arm which will be a whole other game to repair...

btw - what do you use to get the countershaft sprocket nut off, a 1 1/2 deep socket?

Homemade super duper deep socket.
Don't forget Lefty tighty , righty loosy on this one. Left hand thread.

Don't sweat the welded up sockets unless just got to. I find a big ole 1.5" end wrench works a treat with its decent engagement angle and long handle. If parts properly in line there's no reason to strain things as sure can trying to get the set screw in line. Many ways to lock up the various spinning parts but I like to use little square plates 1/4" thick Al plates, at least two needed, one to trap between clutch center and basket, another longer rectangle to snag basket teeth against the center mount post.

Tried using a 1 1/2" BFW borrowed form a contarcor friend. He uses it bolt up anchor bolts to foundations. Three off us wrestling bike on stand , wrench and brake couldn't get enough pressure on the countershaft bolt without it slipping off. Got a 3 1/4" deep impact socket from NAPA after searching Autozone, Harbour Freight, Princess Auto and CTC. It was dear at $32, but countershaft nut came off easily using an air impact wrench. The nut was on with the chamfer side out instead of against the sprocket. Now on to the rear brakes, then swingarm before reassembly