To the two Kens who posted a few days ago:
I also had the problems of a speedo reading too high and the tach too high on my
GT-6 Mk3. I have been sitting on the sidelines the past few days waiting for
someone more authorative to answer - my memory is a bit fuzzy on the resolution.
First the easy one to diagnose, the tach. My tach was reading 5000 at a true
3500 rpm. I replaced the tach and the problem was resolved (until the tach
seized and sheared the teeth off of the tach drive gear on the distributor). I
have been tachless for several years - anyone have a distributor core for sale,
GT-6 or TR-6 that has a good tach drive gear?
With regard to the speedo issue, from memory (dangerous thing) the speedo is
specific to the rear end ratio. My car was a nonOD and also had a 3.89 rear end
ratio when I bought it and the speedo was off by about 20%. I installed an OD
trans and the problem persisted. After the diff blew apart I replaced it with a
3.22 (I wanted the OD to drop the revs at cruising and not to give me a tighter
ratio final drive - how Triumph built the GT-6) and now my speedo reads 2 mph
less than my wife's Saturn at 40 and at 60 mph. Suggest looking for a speedo
from an OD car (or change the diff ratio).
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