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
Gear ratio is always a compromise. For best mileage you want the overall ratio (Trans, rearend and tire diameter) to keep engine RPM at most efficient point at the normal road speed. And because you loose more to friction when you turn the output faster than input, ideally if the rear ratio did all the reduction and top gear was direct you should be best. But that high speed rearend would strain the housing, driveshaft, transmission, clutch, motor-mounts, frame when starting the load. Remember, at take off, peak HP, peak torque don't matter, it is the torque just above idle that matters.
To gain the extra strength the rest of the vehicle would need to be built heavier, need more fuel to move the extra weight.
Back about '75 my parents bought a new TT. After the first trip Mother called me crying, the I6 in the '69 Econoline would not pull it, they could not buy a new TV. I don't remember what the original ratio was, (near 4:1) but I changed the ring and pinion to a 4.88s. (And replaced the clutch that had smoked) That was enough of a change to let them camp for a few years. Dad said he lost some mileage on the highway but it did not change in town.
To gain the extra strength the rest of the vehicle would need to be built heavier, need more fuel to move the extra weight.
Back about '75 my parents bought a new TT. After the first trip Mother called me crying, the I6 in the '69 Econoline would not pull it, they could not buy a new TV. I don't remember what the original ratio was, (near 4:1) but I changed the ring and pinion to a 4.88s. (And replaced the clutch that had smoked) That was enough of a change to let them camp for a few years. Dad said he lost some mileage on the highway but it did not change in town.
