Stewart Warner Speedometer Cable Reducer Gears

[Lugnutt]

Hello all,

I've got a 72 Chev K10 350/350 that I bought new from the factory years ago with L78x15 tires. My truck came with one of those Stewart Warner speedometer gear reducers but when I moved up to larger tires it threw my speedometer off by quite a MPH. Do any of you know if the gears inside these things can be replaced to align my actual speed with my guage? I see where I can buy a new one for about $75 bucks plus freight but would like to replace the inside gears instead if I can. Anybody out there ever done that before?

Thanks for your response

[blasher]

I just bought a used one on eBay for $30 that had the gear ratio that I needed. I took it apart, cleaned it, and regreased it. You could change the gearing easily IF you can find the right parts. Here is some info I found online for the Stewart Warner units: http://www.garbee.net/~cabell/stewartwarner.htm

[Lugnutt]

Originally Posted by blasher

I just bought a used one on eBay for $30 that had the gear ratio that I needed. I took it apart, cleaned it, and regreased it. You could change the gearing easily IF you can find the right parts. Here is some info I found online for the Stewart Warner units: http://www.garbee.net/~cabell/stewartwarner.htm

Thanks for that info, I'll use the chart to figure out which reducer to look for.

eBay's the game

[blasher]

The most accurate way to determine the ratio you need will be with a GPS. Remove your old reduction box and run the speedo sgtraight off the transfer case with your new tires. Then multiply or divide the difference between your GPS and your speedo. For example, mine was way off after a gear and tire change, my speedo read 48 when traveling 60 so I got one that was a 1.250 ratio (48 X 1.250 = 60). I lucked out and found the ratio I needed right away.