-speedometer

[nomad1500]

my GPS reads 55mph while the speedometer says 40mph, cable good drive gear is red 7 teeth driven gear is K20 teeth rear end gears are 3.07 15" tires on my k10 pickup

 

[Scott91370]

Find a shop and get a new speedo gear.
Sounds like one or more of the following happened:
1) You have larger tires than what the truck came with (15" tires means nothing, it's the overall diameter that matters)
2) Someone changed the rear axle gear ratio
3) Someone installed the wrong speedo gear

 

[Matt69olds]

TCI Auto Speedometer Gear Calculator - TCI® Auto

Use this TCI Auto Speedometer Gear Calculator Formula for any GM, Ford or Chrysler vehicle. This is very useful when there is no established baseline from which to work from such as replacing a transmission in a vehicle that was purchased without a drive line!

www.tciauto.com

You need to know tire diameter, gear ratio, and either the drive or driven gear tooth count. This chart will calculate the other gear needed.

Sometimes the chart says “no gear available” that means there is no gear that can be used with the existing gear, both need changed. You can play around with tooth count, the closer you get to a whole number, the more accurate your speedo will be.

For example, the calculator might say you need a 44.3 tooth. Obviously, you can’t have a gear with 44.3 teeth, your options are a 44 or 45 tooth. Either will get it close, but a 44 would be closer.

 

[Juggernaut]

TCI Auto Speedometer Gear Calculator - TCI® Auto

Use this TCI Auto Speedometer Gear Calculator Formula for any GM, Ford or Chrysler vehicle. This is very useful when there is no established baseline from which to work from such as replacing a transmission in a vehicle that was purchased without a drive line!

www.tciauto.com

You need to know tire diameter, gear ratio, and either the drive or driven gear tooth count. This chart will calculate the other gear needed.

Sometimes the chart says “no gear available” that means there is no gear that can be used with the existing gear, both need changed. You can play around with tooth count, the closer you get to a whole number, the more accurate your speedo will be.

For example, the calculator might say you need a 44.3 tooth. Obviously, you can’t have a gear with 44.3 teeth, your options are a 44 or 45 tooth. Either will get it close, but a 44 would be closer.

This is great info, only problem is finding the drive and driven gears. Anyone know a vendor that sells gears for the 203/205 transfer case?