Jerry, I live and learn from the advice of others. Looking at the numbers the current SM420 puts the engine RPM at 2850 or so at 60 MPH. An overdrive would drop that RPM to about 2300 at 60 MPH. As you said the 235 and 261 power band is 3000 RPM +. The 2nd gear on an SM420 is 3.57, and the 3rd is 1.70, that's a large step to over come. With the Clark 282, 2nd is 4.09, and 3rd is 2.17 add the 4th gear at 1.17 and the engine stays in it's power band longer.
I don't question your logic or numbers. I have a "93 K1500 with an NV4500, 4.11 gears and a 350. Heavily loaded, say a medium sized tractor and an equipment trailer and 5th gear is unusable, even on flat level ground. Just thinking that a 1.5 ton truck with 4.88 (now) rear gear and a 235 would be struggle even harder. Wouldn't the close ratio be beneficial here?
Last edited by TUTS 59; 04/11/2024 4:04 PM.
