[elkyD68]

i have a sneaking suspicion that my speedo is of by about 5-10 mph. dunno for sure though. how easy/expensive is it to re-calculate the speedo?

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Derek Ohlgren

68 El Camino w/ 307 and PG
Flamethrower tailpipes bring a whole new meaning to the term "rice burner"

 

[KAA]

It's as easy as changing the speedometer driven gear in the tranny. Take the speedo cable off at the tranny and remove the fitting which holds the plastic gear. They're colored depending on the number of teeth. It may be hard to distinguish the color if it's been in there a long time. Count the teeth. Go to your Chevy dealer and order a new gear with the correct amount of teeth to correct your speedo error. If you have a 20 tooth gear for example, and your speedo is reading high, you'd want to slow down the driven gear. So, you'd order a gear with more teeth. 21 teeth would be a 5% change.

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Keith
70 El Camino SS L78 396
Currently: 496ci big block, GM aluminum heads, roller valvetrain, Richmond 5 speed.

 

[Barista]

KAA has it right. Check this site for more info, THE CHEVELLE ENGINEER: http://members.core.com/~faldrich/speedo.htm

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Bob Von Kaenel
70 SS 402ci TH400

 

[elkyD68]

thanks guys. am i correct to assume that the only way your speedo can be inacurate is if you change the tire size? if so i'm thinking that i might just opt for the correct size tire next time.

 

[Moloko]

chaning the rear gear can screw it up too im guessing

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Justin Kramer
[email protected]
1968 Chevelle 300 Deluxe Sport Coupe 350ci
1978 Malibu Classic 305ci
Everyone wants their car to look stock and haul ass, my car looks ass; hauls stock.