I think that the CP engineers out of Ottawa knew about the speed tapes on the 'new' diesel locomotives, but they also could apparently nullify the overspeed by jamming a pencil into the apparatus.
Our fast engineer. Bill Austin, now railroading in the next world, had the Track Recording Car 63 on behind him on train #1, 'The Canadian' one day. When the train stopped at Chalk River, the technician roared up to Bill and said: "Do you realize that you were going 93 miles per hour at Cobden, Ontario? Bill said: "Is that all? The speedometer read 102. The FP7 and FP9 units at the time were only geared for 89 MPH.
The tapes on several of the old FP7s could be nullified, but they told me that FP9s 1405-1415 apparently could not be played with. And the FPA-2s, 4082-4083 and 4094-4098, had an overspeed that apparently seldom worked. I was riding on #8 from Carleton Place, Ontario, to Ottawa just before the train was discontinued in 1965; we had FPA-2 4083 and F7B 1908 and we were going 93 mph through Stitt(s)ville. The 4083 was geared for 75 mph, and the brakes went on in 1908, geared for 89 mph, and the bells started ringing in 4083. All the engineer did was drop the throttle down from where it was, the bells stopped ringing, and we continued to gain speed until we got to the bottom of the hill coming into Nepean.
Returning from a convention in 1975 that CP had me attend in Banff, Alberta, we had FP9 1406 and GP9 8514 on #2. East of Thunder Bay, we were doing a mile in 36 seconds, on the long straight stretch before Lake Superior. This is about 100 mph. The 8514 was geared for 65 mph! I was telling this to one of the mechanical supervisors in Montreal when I got back to work, and he roared: "No wonder our GD traction motors are flying apart".
Bytown Railway Society, Branchline, September 2009, page 20.