Message text written by INTERNET:triumphs-owner@autox.team.net
>From: "Frank Crowe" <thecrowes@hotmail.com>
Subject: re: Guage Bezels
>Dave: - last weekend went throught my tachometer and speedometer on my TR3.
>Reference Tony Rhodes teriffic information
>(http://ourworld.compuserve.com/homepages/arhodes) if you haven't seen it.
>Thank you Tony for publishing that!
Frank, Thanks for the compliment. I am glad that it was
useful for you!
>
>Subject: Need 20 tooth Odometer Gear
>
>
>Overhauled my '59 TR3 Jeager speedometer last week and discovered the reason
>that my odometer wasn't working - seems the little gear on the odometer
>cross shaft was stripped. Went to swap the shaft with the one from the trip
>odometer, and found that one of the reasons that the shaft was frozen was a
>small burr in the aluminum casting. After cleaning out the burr, I cleaned
>up everything and put the upper (trip odometer) shaft in the lower
>(odometer) position and everything works great (of course, don't have a trip
>odometer now.)
>
>Therefore, need a odometer cross shaft (the little shaft with the gear on
>one end and the little crank pin that operates the pawl on the other end.)
>Because I have a Kilometer speedometer, this one is a 20 tooth gear
>(possibly the same as the later models?) not 36 tooth like the early MPH
>speedometers. (XK Unlimited doesn't carry parts.)
>
>Any ideas? Thanks very much
Frank, I do have some ideas. Many shows have flea markets, and in my limited
experience, these markets usually have a wide variety of speedos to choose
from for a price of about $15.
The MPH and KPH speedos faces only vary in the markings. As far as I
can tell, there is no physical calibration difference as far as the pointer
is concerned.
The KPH speedos do have 62% fewer teeth on the gear on the odometer wheels
so that it will index more frequently since you travel more KM's than Mi.
The 20 tooth worm screw and worm gear are used on both MPH and KPH
speedos as far as I can tell. The 20's are pretty common on TR6's (maybe
there were ONLY 20's on TR6's) You ought to be able to find a 20 tooth
worm gear in most TR6 style speedos. You can also get the appropriate
overall calibration by using the correct odometer gear. Mix and Match!
I am not sure, but it seems like the calibration on the dial of the KPH
speedos can be translated to the MPH requirement by multiplying by 1.609,
then rounding to the nearest 20. I have not paid much attention to the
KPH calibrations, but I think 800 is a common one. This translates to
1289 on an MPH unit which rounds to 1280.
What is the calibration on yours? I will update the manual to cover
KPH to MPH conversions!
-Tony
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