Simple Speedometer Correction

[68RocketAction]

I figured I would share this since I know allot of us have issues with our speedometer reading the incorrect MPH.

Several months back I replaced the tires on my 68 Toronado. I assumed that since the owner’s manual indicated a radial tire size of 235 R15 then that is what I needed. Therefore, I went with a set of Hankook 235/75R15's w/ whitewalls. Well apparently, the world today does not measure tires the same way that they did in 1968, or Hankook just sizes their tires differently. They simply do not have the same height and obviously not having the same; height is going to cause the speedometer to read incorrectly… Well over the last few months, I have been trying to understand this complicated speedometer gear teeth thing. Well I learned that the first and second generation Toronado’s (Also assuming any vehicle with a THM425 transmission) have 32 teeth, which cannot simply just be changed out…

Well then, I started reading about these Speedometer Ratio Adapters, which turned out to be a very simple solution to my problem. Therefore, I simply downloaded a GPS speedometer app on the old Android and took the old girl out to see how off she was…

Therefore, I determined when the speedometer set solid at 70 mph my speedometer app indicated that I was actually going 63 mph… So 70 mph – 63 mph = 7 mph… So 7 mph of 70 mph would mean that it is 10% off… Therefore, I went ahead and ordered a Speedometer Gear Ratio Adapter that indicated that it would reduce my speedometer reading by 10%...

BTW, here is the site I worked from. They charged me $62.00 + $12.66 S/H, but you can probably can find them cheaper somewhere else online…

http://www.transmissioncenter.net/sp...n_______va.htm

Well I received it in the mail today and I think it took about two minutes to hook up. Took the old girl out for a drive and now when she sets at 70 mph my speedometer app indicated that I am actually going 70 mph…

[Stubbe]

Wow that is just what I need but the link did not work could you repost or put the part number here?


Thanks
Mike

[68RocketAction]

Oh, I am sorry; I guess the link did not post correctly.

Speedometer World is where I got mine. There number is 1-888-877-1008

http://www.transmissioncenter.net/speedometer_calibration_______va.htm

Clark Brother Instruments is the manufacture. The Clark Brother Part Number is AA09000 and they call them "All-Maker Ratio Adapters.” It is a 0.9000 ratio reducer, which is 10%. Speedometer world sells 2.56%, 10%, 17.6%, 26.7%, 37.5% and 50% reducers and increases on their site. However if you need something different then I would probably just call them.

A local speedometer repair place can also make these up, but they might charge allot...

[Stubbe]

Thank you!

[bcroe]

[quote="68Rocket]
Speedometer World is where I got mine. There number is 1-888-877-1008

http://www.transmissioncenter.net/speedometer_calibration_______va.htm

Clark Brother Instruments is the manufacture. The Clark Brother Part Number is AA09000 and they call them "All-Maker Ratio Adapters.” It is a 0.9000 ratio reducer, which is 10%. Speedometer world sells 2.56%, 10%, 17.6%, 26.7%, 37.5% and 50% reducers and increases on their site. [/quote]

There actually are some options on TH425 trans speedo gears, but not nearly the range
of many RWD. Your solution is an excellent choice. Bruce Roe

[naveed01]

I have been troubleshooting some FM reception issues with my 68 Toronado. I noticed that the top portion of my antenna mount is a little loose. It appears that I needs some kind of 2 prong socket or tool to tighten it up. Does anyone know what size socket or tool I need to get???

[762]

Excellent post! Thank you so much. I'll have to get mine adjusted too.

[tera155]

I wanted to thank the posters of this topic. I just installed the device and now have a more accurate speedo -- thanks for saving me the research. The Toro Board at its best. Rds, Thad Dupper, Colorado

[Otto Skorzeny]

Here's the direct link to the speedometer ratio adapter.

https://transmissioncenter.net/shop/rat ... 8-2012066/

I need to find a friend with a smart phone speedo app to ride with me to get mine straightened out.

And here's a link to the manufacturer's site.

http://www.clarkbrothers.net/ratio_adapters.html

[bcroe]

I need to find a friend with a smart phone speedo app to
ride with me to get mine straightened out.

I prefer to calibrate the odometer, which I can get right to nearly 3 decimal places. No stop watch
or fixed speed driving (impossible) involved, just some good mile posts. The posts aren't individually
that consistent either, but a run of maybe 50 miles will average out their error. If that doesn't bring
the speedometer to around 2 decimal place accuracy, the magnetic coupling needs adjustment.

Another way is to roll the car forward exactly 1 wheel revolution, measure the distance, and
compare that to the gear ratios driving the speedo. Shown on my PHOTOBUCKET. Bruce Roe