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Re: A little speedo gear help needed please.
Quote:
Originally Posted by 1970pelle
I'm running a good 10 miles an hour fast, at 25 and 35.
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Hey Ken, are you saying the truck is actually moving approx 10 mph faster than indicated by the the speedo at 25-35 mph?
If that's the case, you'll need to make the driven gear spin 30%-40% faster. So if you currently have, for example, 10/44, you will need to go to somewhere around 14/40 if I did the math right, and that's a big if. 
Also, I'd check actual vs. indicated speed at 30 mph and 60 mph and determine how far you're off percentage-wise. If it's 33% at one speed and 37% at the other, then try to get as close to a 35% ratio change as possible. Or if you do a lot of highway driving, then focus on the speedo being most accurate at 60-70 mph.
A good way to check actual road speed is with a free smart phone app.
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Mike
1969 C10 LWB -- owned for 36 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes.
1982 C10 SWB -- converted from 250-six to roller cam 350, Vortec heads -- sold
1981 C10 Silverado LWB, 305, TH350C -- sold, but wish I still had it!
1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming.
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!
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