Fred and all,
Maybe I didn't make myself clear. I know that "speed is speed", but the fact
remains that there is a significant speedo error after installing o/d.
It appears to me that the only thing that can cause this is a difference in
gearing to the speedo. I cannot find any parts book that indicates the o/d
speedo drive gear is different from the non o/d speedo drive gear. In fact,
other than the materials used to fabricate them, all TR speedo drive gears
that I have lying around have the same number of teeth. And, yes, it's o.k.
to make adjustments to road speed in order to stay out of the hands of the
law, but what about odometer accuracy, as in rallying? There's enough to do
on a rallye without having to constantly adjust the odometer mileage in
anticipation of the next turn instruction.
So, my question remains: is any lister aware of a different speedo gear
ratio for o/d cars?
Ed Woods
P.S. We fitted the "A" type overdrive to the 76 TR6 gearbox using a new
mainshaft purchased from TRF that allowed us to use all the original steel
bushing internals. Why Triumph made this mainshaft for gearboxes that used
the "J" type, I don't know; but it was a nice option since I'm partial to
"A" types.
-----Original Message-----
From: fred thomas <vafred@erols.com>
To: Ed Woods <fogbros@nb.net>
Date: Tuesday, May 05, 1998 10:59 PM
Subject: Re: TR4 Speedometer
>Ed Woods wrote:
>>
>> Ed,
>>
>> Why would an OD speedo be different from a non OD speedo unless the diff
>> ratio was also different? I'm curious because I've fitted an OD to my
>> brother's TR6 and cannot understand why the speedo is 20% optimistic.
>>
>> Ed Woods
>> -----Original Message-----
>> From: Edward R. Purcell <epurcel@bellsouth.net>
>> To: triumphs@autox.team.net <triumphs@autox.team.net>
>> Date: Tuesday, May 05, 1998 5:01 PM
>> Subject: TR4 Speedometer
>>
>> >
>> >My TR4 speedometer has never worked, so a good used one is on my
>> >shopping list for Carlisle this weekend. Mine shows 1184 for the turns
>> >per mile number on the face. Is this the correct speedometer for a 1964
>> >non-overdrive TR4?. Many thanks for any info on this matter.
>> >
>> >Thanks Again, Ed Purcell
>
>Speed is speed is speed, the only difference is the gear coming out of
>the trnny, how many teeth. O/D has no effect on your speed at all, just
>RPM. The speedo is geared to the trans. not the rear end.
>
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