See, when I was a Boy Scout all I ever got was a woggle
Seriously though I came across this article in a 1987 "Classic Mechanics" It gives chapter and verse on Henks way of repairing fork links. But more interestingly on page 45 "steering" he seems to explains the phenomena of the offset front wheels in M20's (like mine and most others I have viewed recently).

Oh and the picture on the last page captioned M20, is in fact a Triumph 3 or 5SW.
If anyone wants a scan of any of the pages, email me.

Ron

email (option): ronpier@talk21.com

hi ron,what a fantastic article,prolly answers some of the fork issues discussed earlier.i partiularly like the fork link re-furbishment section.i was thinking along those lines myself,but now it is confirmed i have no worries about repairing them.
cheers rick
ps is radco still living?

email (option): richardholt@rocketmail.com

Hi Ron,i just googled Radco,his real name was Frank Farrington,unfortunately he died earlier this year
aged 77.fortunately for all,his wealth of knowledge
is written down for future generations to learn from.
here's a link

http://www.classicbikersclub.com/news/2012-03/frank-farrington
cheers rick

email (option): richardholt@rocketmail.com

Yes Rick I was relieved to read the bit about the front wheel. It answers the question as to why I can only get my right knee to the tarmac and not my left
I will definitely be re-building my wheel later in the year. Ron

email (option): ronpier@talk21.com

what a good article now days all it would say is the frame/engine/gearbox are not repairable take to your local dealer for replacement part did frank know about this WD motorcycle forum and the enthusiam about the BSA M20

email (option): roger.beck@node6.com

I remember seeing this article when it first came out and have been trying to find it since as I thought it was easier than doing a lot of drawings to try to explain the fork link repair, I'm glad you've found it and saved me the trouble of having to do it!

email (option): davmax@ntlworld.com

Ron, you do know that those are New Zealanders, don't you ? They and Australian forces trained for a short time in the UK before being sent to the Middle East.

I'm not sure if Frank Farrington ever really joined the internet age. We tend to think that everyone does but I suspect that there is a large parallel universe out there of old boys with old bikes who have no idea what goes on.

I think I come from there...On the subject of the BSA forks didn't they make the hub narrower when the speedo drive was moved to the nearside, keeping everything in the right position?...It seems unlikely to me that BSA produced a bike with the wheel alignment 3/4" out..after all they could easily rectify that if they had to...and I wouldn't have thought the army would be that keen either...Ian

I didn't really think they were Boy Scouts Rik. But thanks for telling me they are Antipodeans. Ron

email (option): ronpier@talk21.com

Ron, would appreciate a copy of the article if possible.
Thanks
Pete

email (option): cruaser@aol.com

I didn't really think they were Boy Scouts Rik. But thanks for telling me they are Antipodeans.

Ian, strange that this bloke noticed the front wheel anomaly all those years ago. As I have noticed recently. It's not like it's a one off case. A friend who knows my dilemma was at the Purbeck rally last weekend. There were two M20's there and both these had the wheel over to the right.?? Ron

email (option): ronpier@talk21.com

Hi Ron..I'm going to have to look into this more myself...I can't see that any motorcycle manufacturer would produce a motorcycle with the wheels out of line when this could have detremental effects on the handling and goes completely against basic principles (it would fail an MOT for example)..particularly if they didn't have to.
They also issued details instructions for checking wheel alignment..rather superfluous if the wheels are not in line in the first place...If you were to find the wheel alignmnt wrong on a series of M20s it would be more likely that the rear end was out of alignment....I think more careful investigation is required of changes year by year, the possibility of 'mixing' parts from different years and thereby introducing a fault etc. etc. before accepting the bikes were built incorrectly in the first instance..Ian

Ian, your reasoning sounds far more logical. Those engineers (and road testers) couldn't possibly have delivered tens of thousands of machines with unaligned wheels.

The puzzle, if mis-matching is a problem (and it would be if the fork and the rim offset were altered)is that I'd expect it to appear somewhere in the contemporary literature. There would be different part numbers for forks and wheels and surely warnings about the lack of interchangeability / dangers of mixing parts.

This lack of interchangeability also flies in the face of the MoS's general insistence that it was a priority.

I wonder why they changed the speedo drive in the first place? It would also be odd to do that if it required a change of forks and of wheels.

Has anyone examined whether this off-set arises with both the long and the short forks ?

I think you are both right about the mix up of parts. For instance, the small response I got from guys who could check their forks was:- Only Rob Miller has the offset forks. (I will check my road bike as soon as I can). The bike that I did check here (my special) has symmetrical forks and the wheel offset is close to that dictated in the standards book. It seems logical to me that when the pancake speedo drive was first fitted, BSA overcame this by spreading the left fork leg as per the line drawing. They would then have had to re-set the wheel offset. The fact that Radco talked about it as if it was a well know problem all those years ago would possibly indicate that DR's were getting bikes from REME workshops with these mismatched parts? I too also believe that they couldn't have left the factory like it. I have never really had a problem when using a straight edge on my M20. I've always got the wheels in line?? I'm only hoping that I've twisted the rear wheel in the frame to get them in line and not that the frame is bent. Ron

email (option): ronpier@talk21.com

Harping on again! Here is the wheel in my special, with correct (BSA standards) offset and spacing. Clearly not in the middle of frame. Would it not be the case that if you had the correct forks like Rob's, that the wheel would not be built in the centre of forks (which is how others do it) but in line with the frame down tube. In other words there should be a bigger gap on the speedo side?

I wish you would do some checking Ian and tell me the answer.....I feel all alone out here Ron

email (option): ronpier@talk21.com

Hi Ron...The standards book only covers models with the 'newer' type speedo drive and offset fork legs..not models with the earlier speedo drive and 'non offset' legs. So the rim offset figure given in the standards book (which is not taken from the center of the frame) used in conjunction with correctly offset forks and a nearside speedo drive wheel should result in a centrally positioned rim..
This also might not necessarily be wrong for an earlier bike. If the brakeside leg remained unaltered and only the nearside leg was offset to accomodate the speedo drive, then the position of the brakeplate and drum would remain unaltered, as would the rim offset with that side being used as the datum.
I think both early and late bikes have a brakeplate that is dimensionally the same appart from the speedo drive mounting. A check of the parts lists to determine whether the brake plate spacer on that side was also the same would begin to determine whether that side was the 'datum' side, being the same for all years or whether changes to the forks, hub or other parts altered the wheels position on that side as well..I don't have the literature for 39 and earlier BSAs but it would be interesting to know the rim offset figure for these models in relation to later types..Ian

I have checked my earlier 1935 and 1936 forks and they are both parallel, with no side offset. They are also offside speedo drive. Now these bikes do not have the same frame as the M20, as its much more bolt together frame ( and weaker ).

What I can say with the 1936 Empire star, is that when Jake Robbins rebuilt the forks and they were refitted on the bike, I thought the forks were way out of alignment. However, I checked the frame like a car chassis. By hanging the frame level and then used a plumb line dropping to a flat surface and marking the pairs of positions. I them connected each pair of points/diagonals with a straight edge and marker pen, and then measured!. What I found was a frame leg bent at the rear..
To do the above its important the frame is vertical and level and will not move ( A tricky operation with a lot of ratchet straps ). Also securely place a bar the same diameter as the wheel axles in the front and rear fork positions, if you find say the front is level, but the rear is not then you have a twisted frame, the difficult bit is finding which part is twisted. It took me days, but in the end I found the problem, which was the nearside rear section of frame and its corresponding brace was out of whack by 13mm. Once this was corrected, the wheels then came back into alignment.
The problem with the pre M20 frame is that its bolt together arrangement does not give it a lot of side bracing and if dropped I would say could twist quite easily.. The M20 is semi like the older frame at the rear end, so its possible it could do the same.

Hope the above is of some help

Rgds Dave

email (option): d.weston@virgin.net

Hi Dave..Interesting observations..There are a number of forum contributors (and I am one) who have had similar problems with the rear sections of WD type frames..In fact it is a common problem.
It is certainly the case that the rear of the frame must also be checked if wheel alignment and the relative position of the front wheel to the rear wheel is to be used as a method of determining whether the front wheel is in the correct position...Ian

All very good and valid points and guidance tips. I really am anxious to look closely at my wheel and forks. But reluctant to disable my bike whilst the summer has suddenly appeared.
It occurred to me that if you rebuilt your wheel while mounted in the forks, it would be more beneficial to use the centre mudguard fixing to line up with the centre of rim. Rather than equal distance between the legs. Ron

email (option): ronpier@talk21.com

Hi Ron, some other points I found when chasing the wheel alignments on the older frame Empire star. This assumes both front and rear wheels were designed to align with the frames centre section to fork headstock.

1A. It's better to start from the rear first.
1B. Make sure the bar axle placed through each rear arm end is positioned correctly and snugly ( I bolted it as far forward as it would go in its slots and make sure its a good fit).
1C. Now make sure the axle is level ( assuming frame is checked to be vertical .) If not it could be one ( or both) of the rear fork arms are bent up/down.
1D. Now check the chain alignment. This will ensure the hub positioning is correct relative to the gearbox position ( which needs to be checked true as well )if not ok, suspect rear fork arms are bent or any rear spacers could be incorrect or incorrectly positioned..
1E. If all ok, Now check to see if the rim ( less tyre ) is in alignment with the frames centre. If it is not aligned, it could have the wrong rim offset.

2.Now check front wheel alignment.
2A. Bolt and position the front axle bar ( I bolted it in its slots as high as it would go and made sure it was snug ) Is it level?, if not, and assuming all is ok at the rear ( checking that frame at rear is still level and frame is upright), then it could be a twisted front fork headstock ( unlikely to happen unless its been in a big smash ), or more likely both or one fork legs are bent over.
2B. Are fork legs relatively spaced to central section of frame. If not then it could be bent forks again.
2C. If all above ok, Fit front wheel less tyre, check rim offset to each side of fork leg and check that rim is central to headstock/frame. If not, it could be that the wheel offset has been built incorrectly. I have seen this done to counter a bent fork!. Also check that the correct front end spacers are in the correct position.

Now the disclaimer with all the above, is that for the above to work and be true than the central section of frame and wheels have been designed to be inline with each other. I "assume" ( bad word in engineering circles ) that the M20 central frame tube is aligned with its wheels?.. I am not 100% yet on this model, only the earlier 1935-36 bikes which is a different frame.

Anyway hope this may all help and I have not confused anyone. Checking for bent frames/forks can be tricky and its easy to go around in circles, the basis for correct geometry is you have to have a trusted datum to work from, in the Empire Stars case it was the central forged section of the frame which also includes the headstock. With the M20 frame this is a tube, but of signicant diameter and stiffness not to easily distort.

Rgds Dave

email (option): d.weston@virgin.net

I checked out yet another WM20 yesterday. Again the front wheel is over to the right. It seems to me that re-building a wheel in the forks with equal distance between legs is not an option. The wheel must be built with the centre of rim in line with centre of mudguard mount.

I have also noticed on some bikes that the hole in the mudguard for this central mount is not dead centre of the mudguard.....So as to place the mudguard central over the wheel. Ron

email (option): ronpier@talk21.com

Hi Ron,
Still busy with my own fork and wheel; now that the missing nut is under way I hope to be able to add my grain of salt. And Henk is carrying something for you

email (option): viaconsu [at] planet [dot] nl

Morning Hans. Probably my ramblings about forks is getting on peoples nerves by now. What the fork!! I just can't help talking aloud. Ron

email (option): ronpier@talk21.com

It doesn't bother me Ron...I'm always keen to learn something more about the M20. I 'rambled on' for 20 years about the front mudguard stay and nearly as long about the cam spindles before I found the answers I was after!.. ...Ian

email (option): ian@wright52.plus.com

Its not possible to talk too much about old BSA's in my opinion. :-)
On mine I try to set up the wheel to run inline with headstock I assume that's how Bsa intended.
mudguards non centrally drilled etc I think may have been done later by owners & I can't help thinking at least some of the forks have been "straightened " during restoration to wrongly have both legs the same. ... that could result in a misplaced wheel.
its natural to assume one leg shouldn't be splayed out. particularly if the restorer has straightened early forks.

Good point about forks being 'straightened' Fred..Ian

email (option): ian@wright52.plus.com