- 3,022
- 223
- 63
- Location
- eldersburg maryland
this is sort of a continuation of the gear math subject. today i finished installing the .71 od gears. i am very pleased with the difference. the shift from 4th to 5th is almost the same rpm change as the 3rd to 4th shift, not the puny change we have been used to. and with 14.5r20 (same as 11:00-20) tires, it still has enough guts to tackle my 'test hills' and provide good results. i was suprised at the performance, hard to notice any drop in power or acceleration. there is however one potential problem...... the relative speed of the 2nd gear on the mainshaft to the mainshaft itself is 2622 rpm at engine rpm of 2500. this is likely to cause the 2nd gear to want to seize to the mainshaft. i have heard of this problem when stock trucks are run at max speed, and there appear to be 2 different 2nd gears with the same part number. the older gear has a solid web between the hub and gear while the newer one has 3 large ( maybe 1/2") holes through the web. these are not to be confused with the three oiling holes that are small and go in through the hub to the shaft area. does anyone have any info on when and why this change was made?? or is there any published info on how to solve this lubrication issue?? i am inclined to try putting synthetic atf in the trans and see how it fairs, the 30wt i put in today did not eliminate the problem.