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Triumph TR6 - Speedo drive gear

Can anyone out there tell me what the visual difference is between the speedo drive gear in a 71 tranny and the 73 TR tranny? My cd 30448 tells my speedo that I'm going 45-50 and it feels/looks like 35 or under! The original plastic gear was shot and I replaced it. The first thing I suspected was the plastic gear. kadee31The tranny was a OD per the name plate on the trunk lid and the home made rear mount body angle iron bracket. It was apparant that the gear/shafts etc had been worked on as well.
kadee31@verizon.net
Kyran Mackey

Only difference in the speedo reading should be with OD or not
DON KELLY

Your question needs a bit of clarification. It sounds like you have a 73 TR6 with an earlier transmission in it. Is this correct and is it also correct that the transmission is fitted with an A-type overdrive? If not, what do you have?

Here is the basic rundown on speedometers. For the earlier cars, there were a total of four speedometers. Two each tied to different rear end ratios (3.70/1 and 3.45/1) where one was calibrated in miles and the other in kilometers. With the 73 and up cars it gets a bit trickier as there were speedometer changes for US models based on various regulatory standards over the years. But you still have the same basic situation, the key calibrations are tied to the rear end ratio and miles or kilometers. Unlike some other British cars, it does not matter if the car is fitted with an overdrive or not when it comes to speedometer selection.

What is different is the drive mechanism for the speedo between the earlier cars and the later cars. On the later cars it also varies between the standard set up and the OD option. At least both the early and the late OD fitted cars use the same angle drive.
SteveP

Thanks for your replies. Sorry I wasn't clear. I have a 71 TR with a non od transmission that's been repaired some time ago and I'm not sure if the proper gears are in it. Right now, with your reply, it sounds as if I'm barking up the wrong tree. After some thought, maybe my best bet is to drive my wifes car for one mile and then check the TR odometer to see if it will agree to the distance traveled. That should show if the speedo/tranny gears are ok but the speedo clock would be my problem. The TR is slumbering through the winter right now, but you can see I'm thinking of spring. Many thanks again.
Kyran Mackey

ou can send out your speedo to have recalibrate. Might as well have it refurbished at the same time
DON KELLY

Kyran,
I do not think there is a highway in the US that does not have the good 'ol mile markers. A good (stop) watch to time a minute, 2 sticks a mile apart and Bob's your uncle.
Rick
Rick Crawford

Who's Bob?
DON KELLY

They're my uncles (two unkie Bobs on different sides of the family).
SteveP

My Dad's brother of course.
Rick Crawford

Thanks, Rick. I should have thought of that. :-)
Kyran Mackey

This thread was discussed between 03/01/2007 and 04/01/2007

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