Tony:
Sorry, you are correct - I was in MGB mode when I was thinking of speedo
choices!!!!
But, there were two distinct choices for TR3/4 speedo (OK, four if you
include the kph versions). I only have my TR3 books handy, but they show
that the 4.1 axle was factory optional and was offered as "BEING ONLY
SUITABLE FOR CARS WITH OVERDRIVE". Part of this 'high speed' kit was the
suitable speedo. The parts are as follows:
3.7 axle: crown wheel & pinion set #502127; mph speedo #108192; kph
speedo #108193. No speedo tpi numbers given.
4.1 axle: crown wheel & pinion set #505014, 41 tooth crown wheel
#202579, 10 tooth pinion #202580; mph speedo #113631 (service manual)
[the parts book, 4th edition, says #113637 but is likely wrong]; kph
speedo #113632. No tpi numbers given.
Note that for the TR3 (and TR4??), tire sizes were limited and speedos
weren't available for different size tires.
My TR4 was a '65 and had the 4.1 gears with overdrive. I was the third
owner (from 1973 to 1976) and I believe that the gears were original.
Interestingly, as I was just out of high school and living in Ottawa, ON
at the time, this car was not a Canadian version, but came from
Rochester, NY (I still have the licence plates). So, I don't know if the
car was actually shipped to the US with FACTORY 4.1 gears or whether
they were fitted by the dealer, but the car certainly was delivered to
the original owner with those gears. It also certainly had the proper
speedo which was not likely a recalibration (unheard of in my area at
that time), but part of the original 'high speed' kit. Unfortunately,
not having the car anymore, I can't be TOTALLY certain about the speedo,
but I believe that the car had the full 4.1 kit, including speedo.
Dave Q.
'61 TR3A
(now in Neuhorst, SK)
------------------
Tony Rhodes wrote:
>
>>Message text written by Dave Quirt:
>><snip> Apparently some NON-overdrive cars were also ordered with the
>>4.1 gears, so there may be several choices for speedo. <snip> <<
>
> Essentially, the OD did not factor into the equation since the speedo drive
>gear
> is on the output shaft. The differential DOES matter, as did the tires
> originally fitted. At appears that most people who ordered the OD
> stayed with the 3.7 differential. There is some discussion if ANY (TR2-4a)
> cars were DELIVERED with 4.1 in the US. Certainly it was available as
> a stand-alone part, but as delivered installed from the factory, maybe not.
>
> I have yet to SEE or HEAR about a factory delivedred (to the US) speedometer
> calibrated for the 4.1 differential.
>
> Since your ODOMETER was accurate, the gearing was correct, but maybe it
> was re-calibrated after delivery. The dial would have been very interesting
> since the re-calibrators probably did not re-letter the dial to the
> new calibration.
>
> -Tony
> http://ourworld.compuserve.com/homepages/arhodes (for a nice monograph
> on speedo repair and calibration) (and my auto restoration)
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