I know the difference between the 3 and 4 goes as far as the gears are concerned. I was wondering if a 4 series is stronger than a 3 series. In other words, would a 4:10 thick gear with a 3 series be stronger, weaker, or the same, strength wise, as a 4 series with the thin 4:10 gear?

They are of comparable strength. The mounting point of the ring gear flange moves in correlation to the shrinking diameter of the pinion gear. A two series gear is large compared to a four series gear pinion.


Larger Dave

Inside they are the same. There is no difference in the strength of the posi itself. There is a difference in the strength and weight of the gears. The thick gear is going to deflect less than the thin gear, but it will also increase the rotating mass of the assembly. It is a trade off. Which is more important? Aslo, if you decide to change gears later you will be limited to 3.73 to 6.XX gears with the 4 series. You will be limited to 3.08 to 4.88 gears with the 3 series. Which way do you think you might want to go later?