The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-59 Keep the original speedometer.

cmayna · 02-25-2021, 10:59 PM

If the speed/odometer is off, contact your local speedometer shop to see if they sell a sending unit that screws into the gearbox where the speedometer cable connects to, which has modified gears to meet the needs. You then connect the speedometer cable to the sending unit. My local shop just asks me what speed is my speedo reading when driving at say 50 mph? They tweaked the sending unit accordingly and now mine reads perfectly.

This was necessary when I changed the rearend gears to 3.55.

I assume you have a speedometer ap? My favorite is Speedbox. Very simple and extremely accurate.

Cheers

02-25-2021, 10:59 PM	#4
cmayna Registered User Join Date: Oct 2018 Location: Menlo Park, CA Posts: 90	Re: Keep the original speedometer. If the speed/odometer is off, contact your local speedometer shop to see if they sell a sending unit that screws into the gearbox where the speedometer cable connects to, which has modified gears to meet the needs. You then connect the speedometer cable to the sending unit. My local shop just asks me what speed is my speedo reading when driving at say 50 mph? They tweaked the sending unit accordingly and now mine reads perfectly. This was necessary when I changed the rearend gears to 3.55. I assume you have a speedometer ap? My favorite is Speedbox. Very simple and extremely accurate. Cheers __________________ Craig My truck '50 Chevy 3100-5 window If I'm not working on my truck, I'm fishing with the wife or smoking Salmon. Last edited by cmayna; 02-25-2021 at 11:05 PM.