Hello, I have a question..

I bought off eBay a set of 2 girder fork links,
Under the description:
" NOS ORIGINAL ( NOT INDIA ) BSA M20 GIRDER FORK PARTS"
And the 2 photos below:
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The seller is a "Top-rated seller" from Greece, "roulakosbmw", with 100% Positive feedback.

What I actually got was parts which seems to be used, damaged and pre-painted (minium and green drab)
Before I give a super bas feedback. -
Is there any chance that it is an original NOS?...
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Noam.

email (option): noam10@gmail.com

I have to say that I bought a set of girder links off of Chopper some time in the 80's which came from Birminham and didn't look disimular. And if the stories my old dad told me about stuff from the 30's is true then they don't look so bad.

They don't look used to me but they do seem to have become badly rusted in storage and then cleaned up with a wire brush. Whether they're useable will depend on the diameter of the pins so you'll need to measure them first.

Although the rust pitting doesn't look nice, it won't show and probably won't affect functionality.

It's a bit naughty to use one stock picture for this sort of thing and he really ought to despatch them in the condition that they were photographed in.

Not an expert on WM20 parts, but the scrolls on my forks are machine cut, and thus a uniform depth & width.
Those ones look like tey were done by hand using a Dremel or die grinder.

No 1 option is to send the same photos back to the vendor. And see what response you get.

I have bought job lots of supposed NOS parts only to find 1/4 were totally worn out.
However the crap was also wrapped in cosmoline , canvas and string and definately looked like it had been that way for 30 years.
The seller ( not evilbay ) simply told me he bought them from a deceased estate and simply sorted them out according to the labels into like groups and had not looked closely at most of them and actually knew almost nothing about motorcycles as he was a scrap / clearence merchant. He also offerred to buy back the bad bits ( at scrap prices ) if I wanted to send them back.

To me it looks like a reject part, possibly fixed up 40 years ago, not stored properly, then cleaned up with a fairly big wire buff.

When I was at Simsmetal I "liberated" a lot of auto parts from the scrap .
These are now in my shed, along with good new parts, and repairable parts, if I died tomorrow god only knows how they will get sorted and sold on.

email (option): wariron@tpg,com,au

Noam I agree with Rik. They look original but very shop soiled. The brazed bolt head also looks correct. The NOS set I bought were not as bad as yours, but the machining was poor and not very accurate. Check the pins for 9/16" diameters.

Ron

email (option): ronpier@talk21.com

Yes, that's what you get with the cosmoline, it keeps water out for the longest time, but after that it keeps it in, and makes it very bad in a short time!

Bad luck I guess, but the seller should have checked.

Cheers,

Lex

email (option): welbike@welbXX.net

Thanks a lot for your thoughts, guys.

I will try to contact the seller,
I do not have high expectations, thought..

Noam.

email (option): noam10@gmail.com

sometimes WD parts were opened/inspected in storage and re-wrapped, probably the sort of job given to National Service conscripts to keep them occupied. Or maybe even at BSA, knowing the destination for these parts was overseas some kind of fiddle may have been worked, maybe substituting a dud bit for a good one which ended up on the culprits bike?

Be pragmatic Do not rule out some kind of 60 year old naughtiness, rather than intended dishonesty, its always gone on.

I bought some links off this seller...I contacted him even before they arrived as he had listed some more parts using the same photos...(the same photos that you have posted)

I regard this as 'sharp practice' as it means you are not going to get the parts you have looked at and on which you have based your decision to purchase..

I got links which were definitely NOS and weren't as badly corroded/damaged as the ones you have received...

However, the spindles were .005" under the nominal 9'16" bush size so it would seem the parts were originally manufactured to a tolerance that is well beyond what I would like to use today...

I wouldn't want more than .001"-.0015" clearance between pin and bush...

I do have a NOS set of forks and 3 of the 4 links have this larger clearance to the bush. My first thought was that the links were not actually new, though the forks themselves plainly are...
I made up a go/no go gauge to check the bush sizes and these are accurate and consistent...It seems the bushes were sized pretty accurately and a .001" to .005" tolerance was then applied to the link pins...Surface finish on original NOS pins is also variable...

The purchase, at some expense, of the links from Greece was, it turned out, a failed attempt to rectify this, before measurement of what I received and a re-examination of what I already had led me to the conclusions outlined...

Original forks were not manufactured to tolerances than would be considered 'normal' today, or even consistent with other tolerances applied by BSA to other parts of the M20. It can only be concluded that BSA did not regard the forks as a precision assembly...

For that reason I would advise anyone who is looking for small tolerances in the forks against buying new fork links etc. unless they have the opportunity to measure them before purchase...

My plan now is to remake the spindles from scratch....Ian

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

Hi Noam,

Think the forklink in your second picture (with the red/green paint) is definitely used. Think the burrs/flats on the inside edge of the links can only come from hammering them off.

You can easily check with a digital vernier if the pins are round or worn oval.

The other one looks bad to my eyes, could be unused but I surely would not accept it as it is different from the pictures.

Good luck, Michiel / NL

stuff churned out by the 1000s in wartime for a non precision machine by unskilled labour will of course not be up to par.

After all it was only going to end up on the Thistlegorm

Or maybe old parts put back into QM stores to make up numbers on an audit?

[please don't ask me how I know.]

Ian has managed to make BSA forks sound just like Norton valve guides !

Of these too, large quantitiies seem to have come back from Greece and they are variable in form and dubious in materials...something which wasn't reported back in the day.

I can't help wondering if rather than buying OEM, Greece in the 1950s and 1960s was manufaturing locally (whether with official sanction or not) and if these parts have now become mixed up in the 'Genuine NOS' supply chain...

['stuff churned out by the 1000s in wartime for a non precision machine by unskilled labour will of course not be up to par.']


I don't think it is correct to call the M20 a 'non precision machine'...There are numerous examples of tight tolerancing to be found in the specification that would have been maintained in production and would have to have been for the finished product to function correctly...

There was also a normal inspection regime in place, overlaid by the presence of ministry inspectors to ensure that happened as intended...

Personally I don't believe in the 'near enough was good enough' theory with regards to manufacture of the various components any more than I do in the 'they used whatever was lying around' concept at the construction stage...

That is not the way engineering companies operate as it is not a practical method of production...

However, I accept entirely that in some instances the tolerances were not particularly tight by design (not by accident)...There is little point and it is bad practice to produce something to a higher tolerance than that reasonably demanded by the final application...

There is also the fact that a percentage of recently trained workers were used for some operations...but these would have been employed on component manufacture where the tolerance was less important, not on precision work that demanded a high level of accuracy...

Don't forget that the bulk of BSAs peacetime workforce were employed on production in a 'reserved occupation' capacity, excused from war service entirely due to their various manufacturing skills...Ian

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

non precision M20 as opposed to say a Merlin engine I should perhaps have said.

Those scrolls on Noam's links look as if they were doen with a chisel

I think the pictures say nothing. You have to measure them very carefully to see if they are round or oval.
It is said before that the spindles were originally very roughly made.

The correct finished size for the bushes is .5615"-.5630"...(from the M20 standards book)

No size is given for the link pins themselves but it states the clearance between link and pin should be .0005"-.004"...

A pin size of .559"-.561" would result in the tolerance being within this range irrespective of where in the tolerance range either the pin or bush falls...

Thus although there is only a .0015" tolerance on the bushes and a .002" tolerance on the pins there could be up to a .004" clearance...

A clearance of this size produces a very slack fit even if the parts are within tolerance.....

I have measured the new links I have and most are outside of this range with a clearance in the worst case of .007"-.008"...

This means the parts were outside of the specified tolerance when produced..

However, whether these are 'genuine' parts, parts that have been rejected at some point but then put back into 'circulation', simply incorrectly machined parts that have not been picked up at the production stage and still used/issued or are later pattern parts is impossible to determine at this distance in time....

If I had to, I would guess at an inspection regime that checked perhaps only 1 in 100 parts produced or even just a '1st off' and 'last off' from each batch and thus allowed incorrectly toleranced parts to slip through the net...

I've seen it happen plenty of times in manufacturing...Ian

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