As soon as I can afford quality parts, I'm going to swap away from the 3.42s in my diffs.
How do I recalibrate my speedometer after that?
TIA!
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As soon as I can afford quality parts, I'm going to swap away from the 3.42s in my diffs.
How do I recalibrate my speedometer after that?
TIA!
The ECM calculates your vehicle speed based on input from the wheel speed sensors.Originally Posted by URU
You won't need to recalibrate your speedometer unless you change the tire diameter.
2014 RAM 3500 (Aisin) 3.73 4X4 Limited Crew Cab Long Bed DRW. Oil Bypass Filter, Fuel Filtration Kit, Cold Air Intake, City Diesel Actuator, Steed Speed Exhaust Manifold, Glacier Diesel Intake Horn and 50 Gallon Aux Fuel Tank.
Good to know, thank you!
I was unsure if various sensors besides the wheels were involved.
Thanks again,
URU
I'm not sure that's entirely accurate.
On my 17 Jeep and my 21 RAM, I had to adjust the gear ratio for the speedo to be correct.
You also need to consider changes in tire size.
I use the Superchips programmer for the Jeep.
If your truck is pre-19, you can use it too.
21 2500 6.7 4x4 MC....Thuren Coils - Thuren Front & Rear TB's-Thuren FSB- Fox 2.0 Shocks - Amsoil Bypass - Fleece Coolant Bypass - S&B Intake - Banks Diff Cover - Ram Horn and Grid Heater Delete - BMP Fuel Filter Conversion - ARP 625's - Wagler Cam/Solid Lifter Conversion - Hardened Valve Seats - Billet Freeze Plugs - Manton Pushrods - Fuel 18 x 9 +1 Beast Wheels - Nitto Recon Graps - Power Stop Z36 Brakes - KLM Braided Brake Lines - Revmax 700 - ATS TB Delete - Baja Designs Fog Lights - Airlift 7500 Bags - Daystar Cradles - Dynatrac Ball Joints - Synergy DL/TR - 4.10's -
I was wondering about this.
Isn't there a transmission speed sensor that is included in the calculation of the speed?
I'm running a RaceME, so I have wheel size changes covered.
If I'm going to change gear ratios to be able to tow better and quit lugging the crap out of my engine, do I play with my tire size input until the dash is GPS accurate, or what?
Correct.
So, if your transmission doesn't have the correct gear ratio in the computer, it'll shift incorrectly.
Change the differential ratio, then adjust the tire size until your speedometer is accurate.
21 2500 6.7 4x4 MC....Thuren Coils - Thuren Front & Rear TB's-Thuren FSB- Fox 2.0 Shocks - Amsoil Bypass - Fleece Coolant Bypass - S&B Intake - Banks Diff Cover - Ram Horn and Grid Heater Delete - BMP Fuel Filter Conversion - ARP 625's - Wagler Cam/Solid Lifter Conversion - Hardened Valve Seats - Billet Freeze Plugs - Manton Pushrods - Fuel 18 x 9 +1 Beast Wheels - Nitto Recon Graps - Power Stop Z36 Brakes - KLM Braided Brake Lines - Revmax 700 - ATS TB Delete - Baja Designs Fog Lights - Airlift 7500 Bags - Daystar Cradles - Dynatrac Ball Joints - Synergy DL/TR - 4.10's -
Agree, you will need to use AlfaOBD or other software to enter the new differential ratio for the transmission to shift correctly.
2014 RAM 3500 (Aisin) 3.73 4X4 Limited Crew Cab Long Bed DRW. Oil Bypass Filter, Fuel Filtration Kit, Cold Air Intake, City Diesel Actuator, Steed Speed Exhaust Manifold, Glacier Diesel Intake Horn and 50 Gallon Aux Fuel Tank.
The bigger question is what gear ratio are you swapping to?
I don't tow, but I always wish I had 3.73s as they are the best of both worlds for around-town grunt and economy.
I got a 6-year-old, so dropping 3k to gain 110rpm at all gear speeds is probably not worth it, LOL.
For what it's worth, I'm running 4.10s and 37" tires on my '18 HO.
I find that gearing combo to be just right.
Still a relaxed highway cruise when empty, but deep enough gears to work too.
I used Alpha to update the tire size, and the speedo is good to go.
I did not make any gearing-related computer changes, and as far as I can tell, I don't need to.
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