I've been longing to get our last run of the year over with so that I can address the problem of my wheel wobble that occurs at approaching 60mph.
So with the aid of 'Ariel Graham' acting as SIC, we have been doing some serious checking. The wheel is set over to right side of the forks by 1/2", but as we know the forks are offset to allow for the speedo drive.
But we found that by jigging the bike by various means and measuring from different points along with sighting up, that the wheel is dead in the centre of the frame.
Also when I checked my wheel offset against the spec in the M20 standards book, it is exactly the same.
So now we come the the forks and headstock bearings! I fitted NOS spindles and had new bushes fitted and line reamed about 1000 miles ago. There is no wear or play to these.
But I have never been happy with the adjustment to my headstock bearings since I fitted them a few years ago. There was always a tight spot with the handle moved to the left which was only eliminated by leaving the bearings a bit slacker than I wanted. So I'm waiting for one of Ian's headstock bearing kits.
However what I did notice is that whist removing the old bearing cups with one of Robb Nortier's tools, I had to use a Tommy bar with great effort to screw the tool in enough. But once the cups were knocked out, the tool became quite loose in the threads, therefore indicating a severe amount of distortion occurring during fitting.
As far as my wobble is concerned! I'm sure it's just a combination of a worn tyre and an out of balance wheel that has a slight run out at one point.....All of which I will address soon. Ron
email (option): ronpier@talk21.com
I think it is unlikely tyres are the issue here unless you have an 'oddball'. I have run with all sorts from ribbed Speedmasters, Speedway tyres, K70s, 4.00 SMs etc. etc. and like most Brit bikes the M20 is very tolerant to tyre changes, high/low pressures etc...Personally, I've never had any balanced either and not had 'wobble' problems.
If you think the old races were being distorted then you need to check the frame cups for damage and distortion (not round), otherwise you will do exactly the same thing to the new bearings.
A check through the back end for problems may also be a good idea to ensure you haven't got a case of the 'tail wagging the dog'...Ian
I have just spent 20 minutes measuring my frame and bearing cups, all be it with a vernier. I can't find any ovality in anything...thank God!
The bearing cups are slightly bigger in diameter of course and it could be this interference fit that causes the tool to bulk. It has just occurred to me that the tight spot in my steering to the left could just be my headlamp wiring loom?
Anyway I'm going to fit the up rated bearing kit and attend to the other issues mentioned as a matter of course.
It is frustrating when other mates wheel out their bike and ride like the wind with no problems. He wont mind me saying! But I have just Helped Graham (Of Graham and Louise) with getting his forks re-bushed. His bushes and headstock bearings were quite bad, and yet his bike didn't waver at all, even with Lou as pillion. 
Ron
Ah Neale we posted together. I don't no why Photobucket has cut off part of the standards book info. I deleted it and tried again but it's still cut off
email (option): ronpier@talk21.com
Hi Ron,
Just a thought but did you check the forks in the other direction? along the front-rear of the machine.
If the forks are distorted in that direction it will affect the 'rake and trail' of the bike which could cause your wobble.
Maybe you could make some measurements from the frontwheel spindle to the bottom of the frontframe and compare that with another M20. With the forks in the same position/deflection of course.
In my case the frontframe of the bike was bended just below the steeringhead which will, of course, also affect the steering and I bended it back with a hydraulic jack and checked the total wheelbase with my other M20.
Good luck with it, Michiel
email (option): m.wijbenga@hotmail.com
The latest update and time to fess up on a cardinal cock up!!
I received the up graded headstock bearings from Ian today. They tapped into the frame without any difficulty. I then tapped the steering stem in place only to find a severe roughness on turning it from side to side. Then the penny dropped. The front tank bolts were rubbing on the steering stem. Which is a mistake that I'm well aware of and yet it slipped past my scrutiny on the last fork rebuild. I can only assume that the strange cup and top hat buffers have squeezed up a bit allowing the bolts to just hit the stem. None the less I am chuffed to have found this culprit of notchy steering.
For reference. No shimming was required to the new lower bearing but I did add a thin shim at the top to keep the dust cover from touching.
Ron
email (option): ronpier@talk21.com
Hi Ron...OOPS! ...I did that once but the bolts were exerting a reasonable amount of pressure so it was pretty much impossible to go in a straight line and it had to be addressed immediately....Yours must have been pinching the stem a little less...Easily done though. Thanks for the feedback on fitting up the bearings...Ian
email (option): ian@wright52.plus.com
Ian can you let me know what I owe you.
Ron
email (option): ronpier@talk21.com
Nah Dave! I think that might have been more to do with the way the bike was sitting on the uneven floor in my museum....Plus one of us had been drinking 
.
With the bike set square on the bench. everything measures equal.Since I have just assemble the forks with Ian's new headstock bearings I just did another check from bottom yolk spindle to wheel spindle which is 19 1/4" both sides. Ron
email (option): ronpier@talk21.com
Ah good, it was probably my eyesight that was wonky 
Hopefully the problem's solved now
email (option): horror@blueyonder.co.uk
Ron Ron,
Please confirm your fork length (not your inside leg
I get:
Short fork 420mm (16.5”
by tape measure from centre of lower link to centre of axle.Long fork 435mm (17.125”
by tape measure from centre of lower link to centre of axle. Henk posted a 1944 fork drawing which gave a centre of lower link to centre of axle dimension of 17 1/8" (17.125” - 435mm)
What is your number stamped on front of mudguard stem?
email (option): n.gentner@bigpond.com
Sounds like Ron has a WDM20 chopper bike..
...Ian
email (option): Ian@wright52.plus.com
...Ian I think that you're right, Ian. Rather than DU142s and MT110s, Ron's been fitting Bates headlamps and Maltese cross rear lights. I expect that his magneto is a Joe Hunt....
Can we call him "Bobber Ron" from now on ?
No No! You blokes didn't read my post correctly.
The measurement I gave was something Dave and I were looking at.
I have just carefully made the measurement Neale has asked for and I make it 16 5/8". Blowed if I can see a part number though. Ron
email (option): ronpier@talk21.com
We weren't talking about fork length but from the bottom yoke spindle to the front wheel spindle. We took this measurement in case the fork linkages were bent or twisted or the bottom yoke was bent. This distance will change depending on weather the forks are compressed or not, but just wanted them the same. So fully extended it would be a chopper M20
email (option): horror@blueyonder.co.uk
Well done on your eyesight Neale! I have just checked with a torch and magnifying glass and can confirm 66-5014.
I also have these forks below with #66-5014 and are 16 5/8" between spindle centres. Not sure what is going on with the mudguard support? But I'm not bothered as they are for my BSA/Indian special and I'll be putting a nicer top hat spacer in place of the hex. Ron
email (option): ronpier@talk21.com
Hi Ron, Looks like someone might have used the fitting from between the lifting handle and mudguard bracket instead of the mudguard spacer. The mudguard mount also appears to have been shortened...it looks to be too small a diameter at the lower end.....Ian
email (option): Ian@wright52.plus.com
Ahh...the things we used to do...The only parts that weren't chromed on my Gold Star was the alloy racing tank and the frame...I'd probably get dragged down the road behind a standard DBD34 Clubmans if I turned up at a (boring) Gold Star owners club meeting with that bike today...Sadly, 'Iconic' status does have a tendency to produce very dull, identical motorcycles...Ian
email (option): Ian@wright52.plus.com
I now have my bike back together. Happily my back wheel is dead in line with the front. Just wondering if it's ever going to stop raining long enough for the roads to dry out? Ron
email (option): ronpier@talk21.com