[TR] HVDA 5-speed in TR6--speedo gear

[Tim Gaines]

Thanks for the reply.  I think my odometer is about as far off as the speedometer.  In my calculations I took into account tire diameter and final drive ratio to get the number of revolutions of the tires per mile.  The drive gear teeth (10 or 11) gives the number of teeth per revolution of the drive, and my Smith gauge is calibrated to 1120 revolutions per mile.  I don't see anything that easy to change here.  What am I missing?  I now have the car on stands, and it appears to be easy to unscrew the one bolt holding the speedo driven gear in.  If I can find the right replacement to hit the 2.5 gear ratio I need, I'd still like to avoid getting behind the dash.

Tim

----- Original Message -----
From: "Geo Hahn" <ahwahneetr at gmail.com>
To: "Tim Gaines" <mtgaines at presby.edu>
Cc: "Triumphs" <triumphs at autox.team.net>
Sent: Thursday, February 2, 2017 12:26:20 PM
Subject: Re: [TR] HVDA 5-speed in TR6--speedo gear

On Thu, Feb 2, 2017 at 8:13 AM, Tim Gaines < mtgaines at presby.edu > wrote: 

...my Smith speedometer reads slower by about 5-7 mph than a gps tells me... 

How accurate is your odometer? That (IMO) is the indicator of what recalibration (if any) is needed. There are several things that can cause the speedo to read high or low and fairly simple ways to correct some of them. 

I'm not saying you do not need recalibration - just mentioning there are several aspects to instrument accuracy. 

As for which end to work with - I would much prefer getting behind the dash and unhooking the speedo to getting into the gearbox. 

Geo 

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