I am shortly embarking on tarting-up my 1960 Brum and I am confused as to what Fork yoke it should have. I wanted to attach a couple of photos which clearly show differences in the design between the one on my bike and that offered from the Club spares scheme circa 1956 vintage but they exceeded the maximum file size. Reading Geoff Cases’ excellent article on Brum forks he makes it clear that there was a modification to the oil damper tube and a rubber buffer stop but was there also a change to the design of the yoke ? If so, what was the point as the mods mentioned by Geoff would not have necessitated any ( expensive ) change to the forging for the yoke.
Would the ’56 one be for Dowty forks ? Our 1960 has spring forks.
Hi Charlie. The Brum yolks are the same as the last of the shipley built bikes,(with air/oil fork legs). The lenght of the yolk stem is not exactly the same but both will fit. The internal mods are later owners work,not factory done mods.
Does anyone have a diagram of the internals of the forks on a Brum? Kevin
Hi big Kev, For full info and drawing of Brum forks see Yowl August 2005. Four other articles covering the stuff unique to the Birmingham model in the following Yowl journals, 2005/2006. Geoff.
Yokes were made by Dowty of course, and with various minor differences the Oleomatic forks were also used by Velocette, Panther, AJW, and others. When Matt Holder converted them to conventional coil springs on the later Brum bikes he still used the basic Dowty yokes, etc.. My 1972 Brum even had the notch cutout on the edge of the top yolk, where the Kilner valve was on the Oleo type forks.
So THAT’s what that “U” shaped cutaway is ! I thought that that must have been some accident to do that ! Why didn’t Matt make his own copy of Roadholders rather that design what he finally put on his Brums that can at best be described as charmingly eccentric ?
Hi again, I’m sure that Matt acquired many sets of Dowty forks when he acquired the remaining Shipley stock in 1950, and ‘Waste not, want not’, they were used as standard on the earlier Brum machines. What made him decide to do a conversion to coil springs I don’t know, but it may have been the Dowty factory concentrating on powered pit props, and going away from aircraft oleo legs (undercarriages), and all motorcycle products, resulting in no spares or service back-up. They are just my thoughts on the matter! A few Brum Scotts were built with Norton Roadholder forks, and I have a photo of Matt somewhere with a bike fitted with them on trade-plates.
Hi All, About ten years ago I owned a set of Dowty oleomatic air/oil forks, and a set of brum spring forks, as fitted to most of the (about 300)Brum Scotts produced by Mat Holder,(aerco jig &tool). The Dowty made forks are very well engineered, as you would expect from a company making hydrolic rams and aircraft landing gear. Matt fitted a few of the early (Prototype) Brums with Dowty Oleomatics, The production Brums all have forks with springs.These forks are no way near as good as the Dowty Oleomatics. NO PARTS are interchangeable, except for the top tubes,and the top & bottom yokes which hold them. Everything else has some differences. The bottom (chrome) leg is about 2 inches longer,and the chrome is “decorative” not industrial hard chrome, ground to size as are the dowtys. Fitted with modern seals Dowtys can be air tight and stay up very well. With a few mods Brum spring forks can be made to work a lot better. There were spring kits sold to convert Dowty Oleomatic forks to spring operation,but are not the same as the brum type. The full story is told Yowl article (august 2005) Geoff.