They are Mafac RACER brakes, but they only started writing the model name on them in the early 1970s, when numerous other models made it necessary to distinguish among Mafacs. So yours date from between 1952 and the early 1970s. The earliest had a thicker, more square arm (in profile).
See http://www.vintagebicyclepress.com/
If you have a set of those, I'd gladly pay you a good sum for them. The very first one had an oil hole to oil the pivot (barely visible in the photo referenced above, on top of the pivot).
The last "Dural Forge" already had the plastic bushings that all "RACER" ones had. -- Jan Heine, Seattle Editor/Publisher Vintage Bicycle Quarterly c/o Il Vecchio Bicycles 140 Lakeside Ave, Ste. C Seattle WA 98122 http://www.vintagebicyclepress.com
I've just pulled my Mafac centerpulls up out of my basement stash of
vintage bike parts and I'm using them for my Cinelli S.C. build. I've
read Jan's article in RR but I still can't i.d. them. All it says on
the front arm is "DURAL FORGE" on the left and "MAFAC" in the center.
Anyone know what model these are?
Thnx,
D.M.