I've gone out to the shed to refit an engine steady cos the bike came without one.. and nothing fits. the stud is a bolt, and is knackered and a contrapted piece of scrap, so what should it be please ?

dia
length
thread length..

and are the nuts oversized ?

email (option): chris.astinbarker@btinternet.com

Some WM20 Parts books correctly list a bolt.
Unfortunately some BSA parts books interchange the descriptions, stud/bolt.
Some BSA parts books list the lengths of fasteners, however you also have to be aware the quoted length does not usually include the beautiful radius end of thread.
Some BSA parts books have errors.
To live in harmony with old motorcycles, you just have to accept these challenges.

66-4636 Seat lug and backstay stud/bolt, (BSA dimension 7/16” x 4-3/16”).
However examples of what appear to be 66-4636 actually measure 4.020” including domed end.
Thread is 7/16” CEI 20TPI. (different thread to 7/16” UNF 20TPI)
Curiously the hex size used for 7/16” fasteners on early BSAs appears to be to no known standard. Probably a BSA standard.
Examples of 66-4636 have a hex size of approximately 0.7795 inches or 19.8mm across flats.

M202 Nut, for seatlug and backstay bolt, (7/16” x CEI 20TPI, hexagon is standard Whitworth.

Hex of nut is slightly larger than bolt hex.

To avoid possible disappointment and ensure your personal satisfaction, I suggest you offer up stay and washers etc and measure your actual bolt requirement.

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

Not what you asked for, but Here's a link to some additional head steady info...


http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1197253&cmd=show

email (option): teladelujo@msn.com

thanks chaps...

email (option): chris.astinbarker@btinternet.com

hi,im looking for some input on the nut that holds the same bolt in place.
on my original WM20 the nut was on the left side as you sat on the bike,
and resembled a sidecar lug,however there were no other lugs on the bike.
there was one on ebay recently with the same nut 271101613054
any ideas anyone?
cheers rick

email (option): richardholt@rocketmail.com

pictures of head steady in place..hopefully helpful on some level:

email (option): teladelujo@msn.com

rick

hi,im looking for some input on the nut that holds the same bolt in place.
on my original WM20 the nut was on the left side as you sat on the bike,
and resembled a sidecar lug,however there were no other lugs on the bike.
there was one on ebay recently with the same nut 271101613054
any ideas anyone?
cheers rick

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