head scratcher
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texasSlick
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From a guy who makes rear axles for commandos , madass140.....The standard swingarm width is 205 mm, or a tad over 8 inches.
You might review this thread ....
https://www.accessnorton.com/NortonCommando/one-piece-rear-axle.11848/page-9#post-164169
Slick
You might review this thread ....
https://www.accessnorton.com/NortonCommando/one-piece-rear-axle.11848/page-9#post-164169
Slick
Fast Eddie
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Don lists 3 axles: pre Commando, early Commando and Cush drive.
He does not list a MK3 or ‘disc hub’ version.
Is the MK3 different to pre MK3 with regards to width?
He does not list a MK3 or ‘disc hub’ version.
Is the MK3 different to pre MK3 with regards to width?
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quite sure. measure your swingarm if you have MK3
Fast Eddie
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So, we know the width of pre MK3, and MK3.
The piece of information that seems to be missing from this thread is the actual width of Seattle’s swing arm.
We know yours is wider than Reggies MK3 at 8 3/16 and narrower than the eBay one at 8 1/2... Could you measure it and let us know?
If we split the difference, we are down to a few 16ths. I thought swinging arms generally tended to need pinching up a little as the manufacturers made them that way to easy wheel fitting etc?
Is it possible that yours is fine?
The piece of information that seems to be missing from this thread is the actual width of Seattle’s swing arm.
We know yours is wider than Reggies MK3 at 8 3/16 and narrower than the eBay one at 8 1/2... Could you measure it and let us know?
If we split the difference, we are down to a few 16ths. I thought swinging arms generally tended to need pinching up a little as the manufacturers made them that way to easy wheel fitting etc?
Is it possible that yours is fine?
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Eddie,
I live in Seattle, as seattle##gs does, measured a spare MKIII swingarm I have, and if I remember correctly it was about .25 inches narrower than the first swingarm that started this thread.
This is probably the swingarm seattle##gs bought:
https://www.ebay.com/itm/70s-Norton...D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557
Fast Eddie
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And that’s where seatle got the info from that his is “.250” bigger than everyone else’s”.
But with the info from Reggie and the “eBay purchase” that no longer seems to stack up.
Maybe your spare is narrower than stock?
Probably not, but I’m just saying that accurately measuring his swing arm, so that figure can be compared to others, would really help to clarify this ‘head scratcher’...
But with the info from Reggie and the “eBay purchase” that no longer seems to stack up.
Maybe your spare is narrower than stock?
Probably not, but I’m just saying that accurately measuring his swing arm, so that figure can be compared to others, would really help to clarify this ‘head scratcher’...
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I believe there's been another thread here somewhere, that had a consensus measurement for the MKIII swingarm, that was the same as my spare one.
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The "bargain" swingarm from ebay measures 8 1/2. The other one is on the bike and can't be measured accurately until the wheel comes off. When I held the ebay swingarm up to the other one, the ebay sw was definitely wider. I already have a 1/4" spacer between the hub and the rotor just to make the disc center in the caliper. My solution...look for another sw and measure before I buy it. Anybody want an extra-wide swing arm for cheap? Open for trades.
Mr. Rick
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My SA is "sprung" closed. so needs prying to open enough to fit final spacer. It moves open 1/4" easily once I get purchase, and I have no doubt that if it were 1/4 or even 3/8 too far open to begin with, I cd easily bring it home with the axle (or nut, in my case).
I really don't see the problem here, forgive me.
I really don't see the problem here, forgive me.
Fast Eddie
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I’m just trying to suggest getting some good, solid, baseline info here.
Seattle, unless you get an actual measurement of your swinging arm, you’re flying blind mate, buying random 40 year old SA’s off of eBay ain’t the way to resolve this. How do you know they’re ‘correct’?
It wouldn’t surprise me at all to find that there were a few 16ths differences within factory control limits to begin with!
We’ll avoid pages and pages of beating around the bush if we just measure the offending SA...
Once you’ve done that, you can ask others on here to do likewise and get a good comparison. It wouldn’t even be unreasonable to ask Andover Norton to measure a new one.
Then you’ll know what’s what. You never know, as Mr Rick says, you might even find there’s nothing wrong with it!
Seattle, unless you get an actual measurement of your swinging arm, you’re flying blind mate, buying random 40 year old SA’s off of eBay ain’t the way to resolve this. How do you know they’re ‘correct’?
It wouldn’t surprise me at all to find that there were a few 16ths differences within factory control limits to begin with!
We’ll avoid pages and pages of beating around the bush if we just measure the offending SA...
Once you’ve done that, you can ask others on here to do likewise and get a good comparison. It wouldn’t even be unreasonable to ask Andover Norton to measure a new one.
Then you’ll know what’s what. You never know, as Mr Rick says, you might even find there’s nothing wrong with it!
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Mr. Rick
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I'm suggesting that the inside measurement shd be reasonably close, but is not all that meaningful.
My Mk2 is too low by about 4 mm, falls into place once I get all the stuff in there. If it were 6 mm the other way, it still wd work fine by cinching up.
The Mk3 has different demands, needing to line up both the sprocket and rotor as I just realized.
Is it possible that the caliper to front sprocket center lines are different than the rotor to rear sprocket centers? If so, maybe that's the problem.
If not, and they are the same, is the whole business shifted sideways so neither lines up? Can the caliper be shimmed out or in?
My Mk2 is too low by about 4 mm, falls into place once I get all the stuff in there. If it were 6 mm the other way, it still wd work fine by cinching up.
The Mk3 has different demands, needing to line up both the sprocket and rotor as I just realized.
Is it possible that the caliper to front sprocket center lines are different than the rotor to rear sprocket centers? If so, maybe that's the problem.
If not, and they are the same, is the whole business shifted sideways so neither lines up? Can the caliper be shimmed out or in?
Fast Eddie
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I’ve got a mk2a and my SA is a few mm too wide and need ‘nipping up’!
Back to Seattle’s problem, I’ve not got a MK3 so please excuse the stoopid question here, but, if the rotor is fixed to the hub, and the caliper is mounted to the carrier, and the carrier is located on the wheel spindle and held tight against the bearing inner in the hub, then surely the rotor and caliper will always line up irrespective of any other issue?
Or have I once again overlooked the blindingly obvious?!
Back to Seattle’s problem, I’ve not got a MK3 so please excuse the stoopid question here, but, if the rotor is fixed to the hub, and the caliper is mounted to the carrier, and the carrier is located on the wheel spindle and held tight against the bearing inner in the hub, then surely the rotor and caliper will always line up irrespective of any other issue?
Or have I once again overlooked the blindingly obvious?!
texasSlick
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I agree with all above about the following points:
1) factory tolerances were probably +/- 1/16", perhaps even more.
2) swing arms spread or pinch up easily, and as much as 1/8" too loose or tight can be ignored.
3) 1/4 to 1/2 inch excess spread is not normal.
There must be a reason for the OP's problem. As I posted previously, he should lay a straight edge alongside his arms to check for a "bow". He has not verified doing so.
I had such a bow that reduced my swingarm spread 0.140 inches.
Slick
1) factory tolerances were probably +/- 1/16", perhaps even more.
2) swing arms spread or pinch up easily, and as much as 1/8" too loose or tight can be ignored.
3) 1/4 to 1/2 inch excess spread is not normal.
There must be a reason for the OP's problem. As I posted previously, he should lay a straight edge alongside his arms to check for a "bow". He has not verified doing so.
I had such a bow that reduced my swingarm spread 0.140 inches.
Slick
Deets55
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Nigel,
Yes, you are correct the relationship between the rotor and caliper will not change with swing arm width. Assuming all the proper pieces are installed correctly.
Pete
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