73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Interior & Equipment => Instrumentation => Topic started by: Eastonfrench on September 21, 2015, 11:46:13 am
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Hey guys, I've got a speedometer that reads 75% lower than actual speed. I've done the math and know what ratio I need, but I can't find the parts. My speedometer cable runs off the worm gear In my np205 transfer case.
I know I can buy a adapter box that amps my revolutions up 25%, but they're 90 bucks plus shipping. For a small gear box!
The current driven gear looks like this picture I will attempt to attach.
It has 18 teeth. Does any have, or know where I could get, the same gear with only 14 teeth? That's what I would need to get close to accurate, but I can't find one anywhere. Here's a picture: (fingers crossed, it's my first image post)
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When you get time tomorrow call TCi or any other reputable transmission manufacturer and tell them your set up. They will be able to tell you the driven and idler gear toothe pattern to meet your needs. Make sure you know your drive train info b4 calling it will save you time to know tranny, tranny modifications if any and differential ration as well as any t-case gearing modifications. You can also contact them on their website and they will get back to you fairly quick with the solution to your issue
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I know the reduction ratio I need. I just need to know where to find a 14 tooth version of the part i showed. Any ideas?
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Take a look at the Off Road Design (http://offroaddesign.com/NP205Tech.htm) website for NP205 pencil gear information and interchangeability. Scroll down to "Speedometer Parts." Your best option maybe to use a ratio adapter.
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transmissioncenter.net sells speedometer gears