Why 4.1 axle?
I tow an 8000 pound trailer with a GMC 2500 with 6.0l engine, 4 speed transmission, and 4.1 axle ratio. I rarely need 3rd gear on the highway; only on steep hills. For my next truck, why not get si...
Forum Discussion
time2roll wrote:
4.10 is for this:
Only reason to consider a deeper rear end ratio with new trucks is if you are towing beyond the max rating of the other rear end ratios. In some cases that will raise the tow rating.
What counts is the overall gear ratio from crank shaft to pavement. This includes transmission, rear end and even the tire diameter.
Back in the day when 3 speed automatics were the standard, motors had far less torque & HP and the power curves were more peaky, you ran into situations where the truck couldn't get a good gear to keep the engine at it's ideal RPM for torque/HP. This often resulted in running in 2nd gear with the engine under-loaded but screaming at high RPM (also bad for MPG).
By dropping the rear end ratio, often, the truck could stay in 3rd and keep the RPM more reasonable and gain back some MPG WHEN TOWING. Driving around empty usually resulted in worse MPG because you overshot the ideal RPM.
4 speed trans helped but still ran into the issue some times.
With 8/10speed transmissions, it can dial in the gear ratio to what the engine wants.
