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

Mon Feb 6 06:14:05 MST 2017

Here's a link from my site 
(http://tr6.danielsonfamily.org/Files/SpeedoRepair.pdf) to the Tony Rhodes 
article on how to repair your speedometer if you're so inclined.

I had mine rebuilt by West Valley and find his work excellent, reasonably 
priced and delivered when promised. There's 3 parts to his work: calibrating 
the speedo, ratio change so the odometer is also accurate and rebuilding the 
cable. The cable is critical, as an out of spec tip can ruin a newly rebuilt 
speedo. You can find the spec info on my site 
(http://tr6.danielsonfamily.org/SpeedometerCalibration.htm). I had him do 
all three things in 2008 and the cost was $215. If you don't care about the 
odometer accuracy, you can save a few bucks.

Or you could do what I ended up doing a couple of years ago.... I had West 
Valley convert my Smith speedo to GPS.... with a GPS speedo you never have 
to worry about diff/tranny gearing or tire/wheel size. And it's deadly 
accurate.

Bob

Bob Danielson
http://tr6.danielsonfamily.org/PanelBootSales1.htm
Custom Interiors & Boot Covers
http://tr6.danielsonfamily.org/FenderBlanket.htm
Fender Blankets

-----Original Message----- 
From: Tim Gaines
Sent: Sunday, February 05, 2017 10:06 AM
To: Triumphs
Subject: Re: [TR] HVDA 5-speed in TR6--speedo gear

I have found several possible solutions in my quest to calibrate my TR6 
speedometer after making the HVDA Toyota tranny conversion.  Thanks go out 
to several members of this list and several on the Triumph Experience forum. 
Here is a summary of those solutions.

1.  Keep using a GPS or a phone with a GPS-speedometer app and forget about 
the actual gauge on the dash.

2.  Use a GPS to calibrate the speedo and mark new lines on the gauge face 
or glass with a Sharpie.

3.   Classic Automotive Innovations has an ingenious solution.  A gps 
controls a motor that spins the speedo cable (disconnected from the tranny) 
at just the right (adjustable) speed.  The current price is $275.

4.  As Herman van den Akker recommends, send your speedometer to a shop that 
will replace gears for the speed and odometer mechanisms that will 
accurately recalibrate the gauge.  This requires some accurate measures on 
your part of the number of turns of your present cable per 1/100 mile.  I 
just got a quote from Palo Alto Speedos for $295 to do that calibration.

5.  Buy a speedo ratio adapter for $60 - $120 that attaches to the tranny 
between the speedo gear and the cable and adjusts the cable turns per mile 
(TPMs) to match speedometer calibration.  Different speedo gauges require a 
different number of TPMs.  Whereas most American gauges are standardized at 
1000 TPMs, mine is 1120, and I have heard of another TR6 one being 1180. 
Maybe there are even more values out there.  The advantage of this solution 
is that there are right angle ratio adapters that will help alleviate the 
problem of the tight turn in the speedo cable from the Toyota tranny to the 
TR gauge.

6.  An in-line ratio adapter that connects via cables to both the tranny and 
the gauge.  It does what the above device does.

7.  Find a replacement speedo driven gear with the proper number of teeth to 
change the ratio to match the speedo gauge.  The new driven gear must be 
matched to the number of teeth in the drive gear.  From what I have read, 
that number is 10 or 11 in the W58 Toyota tranny that is often used for the 
HVDA conversion and the value should be stamped on the shaft of the current 
driven gear.  The driven gear can be removed fairly easily from under the 
car by removing a single bolt that holds the gear assembly in place with a 
small metal tab.  I have found only one online site that lists driven gears 
with details about the drive- and driven-gear teeth.  I have emailed to ask 
if all of the Toyota driven gears will fit the W58 transmission, but I 
haven't heard back yet.  I would think that there is a standard for the 
speedo gear assembly across tranny models.

http://parts.lakelandtoyota.com/showAssembly.aspx?ukey_assembly=519949&ukey_make=1060

There are some calculations that must be made to find the right gear, and 
there is a helpful site that guides you through it.  Keep in mind that this 
guide assumes (without saying so) that the speedo gauge uses the US standard 
1000 TPMs.  At the stage where the guide says to divide by 1000 (or 1001), 
you divide by your own gauge value.  That can be found at the bottom of the 
gauge face, partially hidden by the chrome rim around the gauge.

http://www.celicasupra.com/forums/showthread.php?67982-The-end-to-speedometer-gear-questions

I have not been able to find the precise driven gear I need, but I did find 
one that should get me much closer to an accurate readout.  The price of the 
driven gears is about $25 - $35.

Art Liefke sent me the url for a site that explains in detail how the 
British speedometers work and how to calibrate them.  I have only briefly 
skimmed it at this point, but it looks to be a good explanation of all the 
things (and more) I pieced together in several days of looking and reading 
online.

http://www.westnet.com/~mfrank/Speedometer/Smiths.html

Tim Gaines
Clinton, SC
1974 TR6
1980 Spitfire

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