Speedo

[Canadian 4X4]

I have a 77 c10 lwb with 305 and a th350 but the cab is an 82 or 83. The problem is the speedo is is off 10-15 km/h which is 6-10 mph. is it possible to re calibrate the speedo?

[zieg85]

Yes, the calibration is the plastic gear in the transmission and or an additional adapter on the outside of the transmission.  Any trans shop could help but you could do it on your own by finding out exactly how far it is off and what color gear you have in the transmission now.

[1980c10]

is your speedometer off the same amount all of the time or is the gap get bigger as you increase your speed? that will tell you if you need an actual caliberation or a differant gear. I just go to the local speedometer shop for issue with mine. it is pretty cheap for most things.

[Canadian 4X4]

I believe it is off the same amount the whole time, I haven't had my gps with me for awhile but i believe it was off 13km/h all the time.

[Captkaos]

Check this article out: http://www.73-87.com/7387garage/drivetrain/speedo.htm

[1980c10]

what i was getting at is considering you are off the same amount no matter the speed; you probably just need to calibrate it. if you had the wrong gear; the faster you go the bigger the gap between actual speed and the speedo reading. hope this helps.