My neighbour and I were exercising our Morgans on the highway last week at
what seemed to me to be a legitimate speed when we came upon a gendarme parked
on the median. My friend slowed dramatically. Afterwards I asked why he had
slowed when we were doing only 65. "We were going close to 80" he replied.
I had always thought my speedo was reasonably accurate. I also know that 65
just seems like 80 in a Morgan. Also, knowing that British motorcars from
the 60's are geared on the low side compared to modern American automobiles I
had never attempted to equate revs to mph.
So, I went home and pulled out Fred Sisson's "Bedside Reader" and found that
on a 1965 +4, 3000 rpm = 60 mph. I measured the circumference of my wheel,
multiplied by the 3.73 rear end ratio and divided into 5280 ft per mile and Lo
and behold the answer was 3000 rpm.
I then took the car out and matched the speedo to the tach. Guess what? I
found that at 40 the speedo read 35, at 60 = 52 and 60 = 70.
If my car has a 3.73 rear end then my speedometer is about 14% slow.
I then looked at the speedometer face. It reads to 120mph. I then dug out my
immense collection of photos of other people's Morgans and found that most
(but not all) Morgans of that era have speedos that read to 140mph.
If you look at Fred's book p148/149 you will see that he had a similiar
experience so I can only conclude that a previous owner replaced the original
with a TR3 speedometer without having it recalibrated. It has taken me the
nine months I have owned the car to notice this, perhaps because the speedo
had been refinished to match the appearance of the other instruments.
So, for me to solve this mystery and try to put it right, is there anyone out
there who would know:
1. Did all 1965 Morgan +4's have a 3.73 rear axle or was there a lower ratio?
2. Did all 1965 Morgan +4's have 140mph speedometers because I have seen
one other 120mph
3. Is there a vendor out there who could put a 140mph face on a 120
instrument. Calibration would then be unnecessary.
4. Is there a vendor in the US (Mid West) who could recalibrate a Smiths
instrument.
Of course, I could do nothing. A speedometer on this car seems to be
positioned for the benefit of the passenger....and having it read slow maybe
is not a bad idea.
Fred solved his problem by installing an overdrive to correct the ratio but
that solution is too elaborate for me.
Anyway, any response would be wecome
Thanks,
John Rogers
65 +4
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