850mk3 wheel alignment.

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hillbone

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Hi. I have run a string line very carefully from back wheel to front. I have about a 2 inch difference with the left side parallel with the back and the right side 2 inches away.
I have had my wheel builder insist that his stats were right. The rear caliper is right near the spokes so it cant be moved any further to the right. It appears to in line with the centre of the swing arm.
Do i worry about the 2 inches. ? Some say they are rarely in line.
I have no idea where to go from here as the chain adjusters are not an even guide either. The chain is straight in line with the gearbox sprocket as well. Hmmmm!
 
String can work but needs 2 people, fluorescent tubes work well for single person aligning, different width tyres front to back will also need to be catered for. I rest the tube on the wider rear tyre and check the gap is the same both sides at the front. I use a narrow width jack and safety straps so the tubes have full access and the bike cannot fall over.

Is your front wheel rim central to the fork lowers, the front wheel is one of the hardest wheels to true as the disc side spokes are nearly vertical and as soon as you try and tension the non disc side they pull the rim off centre. If that's not central then it needs to be made central before continuing.
 
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Everything Kommando said and I'd add, also check rear wheel position against centre line of frame.

Just been through this and had similar comments from the wheel builder. I'd ask for the offsets based on measurements from my bike as they seem to vary. It's still a couple of mm out as the original wheel builder didn't drill the rims to match the offsets but much closer than it was.

Commando offsets are not designed to make wheel builders happy...

Quite a few pictures on here and the net of rear wheels offset quite some way from frame centre line. I took some to my wheel builder of those and if mine. He was more convinced in my requested offsets after that.
 
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He has not built the rear wheel correctly, it should not be centre in the swingarm.
There are wheel builders and then Norton wheel builders, sadly it is a trade where they will say ''I know what I am doing'' and many don't when it comes to Norton wheels and rims.
Many of them think that a 40 hole rim is universal, far from it, they must be pierced to the correct Norton pattern for the wheel it will become.
 
Gadge said:
Everything Kommando said and I'd add, also check rear wheel position against centre line of frame.

Just been through this and had similar comments from the wheel builder. I'd ask for the offsets based on measurements from my bike as they seem to vary. It's still a couple of mm out as the original wheel builder didn't drill the rims to match the offsets but much closer than it was.

Commando offsets are not designed to make wheel builders happy...
Click to expand...


I used to eyeball the rear wheel parallel with the frame backbone until a buddy showed me that aligning rear to front wheel eliminated the infamous Commando left lean syndrome.
 
maylar said:
I used to eyeball the rear wheel parallel with the frame backbone until a buddy showed me that aligning rear to front wheel eliminated the infamous Commando left lean syndrome.
Click to expand...

Sorry, I should have been clearer. I meant check the rear wheel is aligned to the frame centre line and have the wheels in line.

I agree, priority is to have the wheels in line. I prefer to have them centred to. At least as near as possible.
 
Madnorton said:
He has not built the rear wheel correctly, it should not be centre in the swingarm.
There are wheel builders and then Norton wheel builders, sadly it is a trade where they will say ''I know what I am doing'' and many don't when it comes to Norton wheels and rims.
Many of them think that a 40 hole rim is universal, far from it, they must be pierced to the correct Norton pattern for the wheel it will become.
Click to expand...

And even the factory had tolerances on that. The factory laced front wheel on my 850 was off center between the forks by about 1/8 inch. After having Buchannan put stainless spokes in it it's now perfectly centered.
 
hillbone said:
I have run a string line very carefully from back wheel to front.
Click to expand...

How exactly? With the string touching the tyres at four points? Or with the string not touching and measurements taken between the string and the rims?


hillbone said:
I have about a 2 inch difference with the left side parallel with the back and the right side 2 inches away.
Click to expand...

Do you mean you projected a line off the RH side of the rear tyre (or rim)? If so, then any misalignment will be magnified at the front so perhaps some more information about how you measured this 2 inch difference would help.

Are the tyre widths different (if you are measuring the line off the tyres? If the rear tyre (or rim) is wider than the front then it needs to be allowed for.

hillbone said:
I have had my wheel builder insist that his stats were right.
Click to expand...

Have you checked if the rear rim is aligned/centred with the frame or not (and front rim centred between the fork legs)?
 
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Thanks everyone. A lot to think about. I ran my string touching the 2 edges of the rear tyre, closest to the engine and the rear point. The bike is sitting on a race stand to clear the swing arm.
The 2 strings each side of the tyre then travel to the edges of the front tyre. The left side of the front tyre string is in line with the rear ie it touches the left side of the tyre, but the right string sits 2 inches away from the right tyre.
 
hillbone said:
The 2 strings each side of the tyre then travel to the edges of the front tyre. The left side of the front tyre string is in line with the rear ie it touches the left side of the tyre, but the right string sits 2 inches away from the right tyre.
Click to expand...

That's basically repeating what you've already said but still no mention of tyre widths!
If the front and rear tyres (Edit: and rims) are the same width and are in line on the left then they must also be in line on the right.
 
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hillbone said:
Thanks everyone. A lot to think about. I ran my string touching the 2 edges of the rear tyre, closest to the engine and the rear point. The bike is sitting on a race stand to clear the swing arm.
The 2 strings each side of the tyre then travel to the edges of the front tyre. The left side of the front tyre string is in line with the rear ie it touches the left side of the tyre, but the right string sits 2 inches away from the right tyre.
Click to expand...

Impossible. If the left string is touching all four points of the tyres front and rear, then the right side will automatically do the same - unless your rear tyre is significantly wider by 2 inches?

2 inches is a massive alignment issue, so I would initially check how you are doing the measurements and as others have said, it's probably far easier and more accurate with 2 straight edges.
 
Go over the whole thing again, it's easy to convince yourself that's things are way out
Check and re check
 
It's not rocket science. I check alignment on all my bikes and those I mount tires to and as often as not, the marks on most swingarms are incorrect. Two staightedges tied to the rear wheel as high up as possible. Check the dimensions to the rim to be sure you're good. Center the front wheel in the gap between the straightedges. If the dimensions differ side-to-side in front, you must move the rear wheel to the direction of the tight side and measure again until you have the rear centered with the front. With both wheels and tires the same size, any gap calls for adjustment of the rear. Once you get the wheels aligned, if anything looks cockeyed, you may have to have a wheel re-spoked for a different offset. I've never seen this sort of misalignment with cast wheels.

Once everything is straight, check or make marks on the arm if you like. I count flats on the adjuster bolts to get proper chain tension.
 
All these suggestions assume that the engine cradle, to which the swingarm and rear wheel are fixed, is perfectly aligned in the frame.
This is not a given thing.

850mk3 wheel alignment.
frank horrigan fallout 3
 
hillbone said:
Hi. I have run a string line very carefully from back wheel to front. I have about a 2 inch difference with the left side parallel with the back and the right side 2 inches away.
I have had my wheel builder insist that his stats were right. The rear caliper is right near the spokes so it cant be moved any further to the right. It appears to in line with the centre of the swing arm.
Do i worry about the 2 inches. ? Some say they are rarely in line.
I have no idea where to go from here as the chain adjusters are not an even guide either. The chain is straight in line with the gearbox sprocket as well. Hmmmm!
Click to expand...
What is the history of the bike?
IE have you just had the wheels rebuilt and suddenly it's out of alignment?
Or ihas the whole bike been rebuilt?
As Ludwig says the ISOs play a huge part in alignment issues with a commando
 
Two of these mounted to plates on the rear wheel proved very helpful when I was aligning the wheels and verifying offsets

850mk3 wheel alignment.
 
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