This is the Girder Fork main spring, as fitted to all 1930's Norton girder forks in the 1930's through to 1946. It is UK manufactured by our trusted spring manufacturer, using an original Norton main spring as the template. It is supplied black satin coated, ready to fit.
It is worth noting that it is very difficult to find original Norton girder fork springs that can be trusted as having the correct original dimensions - I have seen many other springs fitted, or those original clearly look tired. We took some consderable time with various original springs to ensure we had a correct and definitive original, I also conferred with old friend and SOHC expert - Stu Rogers, and agreed the most definitive spring commonly fitted - using this as the pattern.
It is worth saying that I have seen various reproduction springs on the market in recent years, and certainly at least one of these that I have checked has had very different dimensions to this original Norton item! Email us on firstname.lastname@example.org if you wish to check dimension of your spring against these springs.
These have been manufactured by our main UK spring manufacturer, who makes the majority of our springs (as well as having made other makes of girder fork main springs for other historic suppliers in the past), and they look of excellent quality. We have also had them satin black coated, so should be ready to fit direct to your bike - unless you wish to further coat them with either a gloss black or Matt army green (if fitting to a WD16H). Each spring comes supplied in protective paper and sealed bag to prevent scuffing in storage.
Accompanying photographs shows one of these springs next to an original Norton spring for comparision. Also, one is shown fitted to the top spring clasp and M30 (pre-war racing type) girder fork blades of my own 1939 M30 Manx Norton project (I will be using them myself).
Final note on fitting: When fitting fork springs - always wear eye protection and take care. When fitting the spring to the top spring clasp and bottom blades clasp, I find it easier if having greased the clasps first. They sometimes need a bit of jiggling to ensure they have fully revolved round and are seating on the base as fully as possible. It may also be worth checking them after assembly, and having bumped the forks up and down a number of times to fully settle everything. Once having done this, the top clasp bolt can then be loosened off again from the top steering head casting, and with a cloth round the main girder spring, check to see if the spring can be revolved any further to ensure fully seated on the bottom clasp (particularly if fitted to a newly restored bike, where the paint may be thick around the clasp). Final thing is to check the clasp likewise, ensuring tightened as fully into the top of the spring as it can go, then fully tighten top clasp into steering head.