MY 1915 TOURING REAR BOWS HAVE WARPED DOWNWARDS AND ONE SECTION IS COMPLETELY ROTTEN .
WHAT IS THE TYPE OF WOOD USED AND THE WHAT IS THE MEASUREMENTS OF THE STRAIGHT PORTIONS OF TIMBER AND WHAT IS THE OVERALL HEIGHT OF THE REAR IRONS AND BOWS
I think white oak was used. Here is a thread with some top measurements for 1915-22 tops: http://www.mtfca.com/discus/messages/29/21299.html
Save your old wood and copy it. I bought a new set of correct steam bent bows at Hershey in 2012. They still required a lot of hand fitting where the wood goes into the steel sockets. Having the old wood showed me how much/where to whittle to fit the rectangular wood into the oval shaped sockets.
The shape of the rear bow is different than the front bows too, be careful.