Charles I'll guess you haven't looked too closely at how modern disc brakes mount. The disc brake caliper mounts to a large braze-on to the left fork blade and to another one on the left rear seat or chainstay. This is way more invasive than drilling a couple holes. I guess you could use some hose clamps to hold the caliper in place, but this is a really, REALLY bad idea as the stress would almost instantly tear the hose clamps off.
What you could do, and I have done, is use a drum-brake in the front. I prefer the Sachs but the Sturmey-Archer works pretty well too. best, Brandon"monkeyman"Ives Coeur d'Alene, Idaho
> To avoid hassle of drilling and mounting brakes in front or rear of a
> collectable track frame without holes already there I suggest the use of
> modern disc brakes and correct hubs (way past time line). This avoids
> the potential fork crown or rear brake bridge failure and frame is left
> untouched in original state.
> Charles Nighbor
> Walnut Creek, CA
> PS I seen fixed bikes up on all 4000 feet of it Mt. Diablo and have
> followed them down. All have had brakes. All made it down at about 20MPH