66-5014 fork blade, 1940-41 WD WM20 (1940 C-7287, 1941 RAF) = stamped number identical to part number 66-5014 (420mm by my tape measure from centre of lower link to centre of axle)
IMPORTANT NOTE: According to the parts books, Rons forks and a set I have, 66-5014 forks have their mudguard stem shortened by ½”, i.e. length of mudguard stem is approx 1 ¼” (32mm).
According to the parts books, 66-5014 fork is used with ½” long 66-6557 front mudguard distance piece (machined from hex) as per Ron's pic.

That hex extension stud is the proper BSA part.
The shortening of mudguard stem was done by BSA.
The reason is unconfirmed.

My speculation is BSA went to the 66-5016 long fork for the big contracts but used up what ever was lying around for the small contracts.
The pre war Goldies used this same short mudguard stem to allow clearance for 21" front tyres on competition models, and the same mudguard distance piece 66-6557 when standard wheel and mudguard used on M24 touring models.
By making the special 66-5014 fork with short mudguard stem the WM20 assembly line didn't have to be re-trained to fit mudguard distance piece 66-6557 only on some contracts. And BSA cleared all stocks of M24 fork castings.

BSA were once very adept at economical mass production.

email (option): n.gentner@bigpond.com

Good work Ron!

The "Standards" rim offset data for rear wheel is a little unclear

For rear left/brake/sprocket side, the straight edge should be placed on the end face of the 15-7046 Hub bearing sleeve/hollow axle (5/8" to edge of rim).

For rear right side, the straight edge should be placed on the end face of the 26-6861 Hub bearing locknut (1 1/4" to edge of rim).

The front wheel data is straight forward and your offset dimension of 1/2" tallies nicely with the 1940-1948 66-5526 Front Hub Spindle (axle) which has an overall length of 7.570” /192.2mm, for offset wheel and fork)

Whereas the 1937-1939 15-7018 Front Hub Spindle (axle) has an overall length of 7.086” /180mm, for non-offset wheel and non-offset fork.

The extra length of 40-48 spindle is all on the left side for:
29-5737 Speedometer Drive Gearbox,(body of drive around axle hole is 0.105” thick)
2 x 36-3528 Front Hub Spindle Locknut Washer (fitted on top of speedo drive, 0.640” x 1.250” x 0.125” thick, same washer as idler spindle in timing chest)
66-5524, Front Hub Washer (Speedometer Drive) (goes inside speedo drive, 0.640” x 0.950” x 0.078” thick)
24-6994, Front Hub Spindle Locknut, (left side, goes on top of 36-3528, 5/8” x 20 TPI x 0.920” hex x 0.188 thick, not used 37-39)

All these 40-48 bits add up to 0.621", however, contrary to at least some BSA parts books, RUSSELL MOTORS state that only one 36-3528 Front Hub Spindle Locknut Washer is used, which brings the stack of bits down to 4 thou shy of 1/2", near as damn it!

Perhaps BSA intended 36-3528 Front Hub Spindle Locknut Washer to be used "as required", so as not to overstress the "war tolerance" fork when axle nuts tightened?

The answers lie in the uncounted rivets!

Good luck with eliminating your wobble, I've never experienced a BSA wobble.

You might have to do some hand scraping so your head bearings remain round.

email (option): n.gentner@bigpond.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

Hi Ron,

I don't have the net at home any more. I'll have to put my drawing onto a thum drive and get byou tomorrow.

email (option): britool51@hotmail.coom

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