Hello All--
Trying to resolve a problem with erroneous speedometer readings, and not
having a great deal of luck. What I can say at the moment is that the
previous speedometer did not work when I purchased the car. Replaced the
cable and it began to operate, but read consistently very high (in
relation to the 4th gear reading of the tach). I suspected that it was
faulty because the needle jumped to 20-25 mph as soon as the car moved.
I am reasonably certain that the differential and transmission are
original (`72 Mk III GT6, non-overdrive). The car simply feels too long
in the lower gears to have a 3.89 rear installed, and even if it were,
the speedometer error is far too high to account for the different ratio
(as well, the road speed estimated from the tach is reasonably
correct--I am mostly with traffic at the estimated speeds, within the
couple of mph error from using 175-70 tires).
The speedometer in the car when I bought it is SN 6203/4, which I
believe to be incorrect--it's a junkyard item--and apart from the
stickiness in it, reads about 115 mph at 68-70 mph. I replaced it with a
speedometer from the parts car (also a `72 Mk III w/o overdrive), and
yet, while it obviously works more smoothly, it reads about 20 mph high
at 50 mph. The serial number on this one is 6203/38A. I cannot test the
one from my `70 GT6, since it is seized--but its serial number is
6203/20. All the tachs accompanying these speedometers are 3.55:1.
It strikes me as odd that there would be so many versions of the GT6
speedometer--I would expect one for overdrive and one without, and yet I
have three with three different serial numbers. Some certainly may have
come from other models (6203/4 has a different numbering on the
scale--showing the last indication as 140 mph, instead of the 130 of the
other two), but was it common practice to have so many variations? If I
have three out of three, there must be more.
Cheers.
--
My other Triumph runs, but....
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