Gear and transmission ratios.

The older style didnt "RTO" series didnt have "A" or "B".

 

There isn't anything showing for a 16913 but an RTLO, the last RTO series transmissions are XX613, these are the last generation before the low inertia trannys.

 

not sure what your going to gain dropping half a gear that is a double overdrive transmission you have

 

Gonna have to get underneath and double check it, but I know for a fact its RTO. I just bought a set of 402's rear ends, housing, suspension, brakes, drums and came with 3;70's for $700.00 and they just went thru the power divider. I was gonna trade the 3;70's for 3;55's But was told I wouldnt get the same pulling power. So now Im waiting for the transmission to go out so I can pick up an RLTO. But the way I drive my truck it might last me quite awhile. So I guess might as well live with it. I know Im putting to the rear wheels close to 600 and gonna change the program to a 5DS this week on a 5EK. So will see how much the drivetrain will handle. Had the 5DS before and never had a problem.

 

The 1742 at 70 is pretty close for direct with mine but I still have overdrive and it's actually closer to 1500 @ 70. I'm running the same setup with 24.5lp, 18913a , 3.55.

 

No, your 18913A has a .73 over drive, as there is no B gear set for the 13spd, the equivalent 18spd would be a RTLO18918B and it would have the same gear set as yours, he is dealing with an A series 18spd with a single over drive of .85, this would be close to 12th gear in yours, my numbers are from using calculations that eaton says to use to figure road speed, so they would be exact except for the small variation in tire size between manufacturers.

 

I had to research it and the outcome was. I was a #######. I thought both had the same ratio but your right. I apparently don't know as much as I thought I did on trannys witch isn't much to begin with. Just what I've been around. (Yes I'm talking about the type of trannys with gears. I don't know a thing about the other type)

 

I will admit that eaton didn't help the fact by not making them the same, I have an excel sheet I go to for ratios that I downloaded from the roadranger site, it has almost all the transmissions before the 16xxx series, and then for the newer one the sales cards you can download have the ratios for them.

 

I'd go with 3.55s. It is the most versatile rear ratio you can use. On 11R24.5s you have some very long legs and can get cruising.

On low-pro 22.5s, you're getting down to the equivalent of 3.70-3.90 rears on tall 24.5s and have some good starting grunt.

There is a point where you have too much gear. Drove a 379 on low-pro 22.5s that had an 18-over (0.73 overdrive) and 3.08 rear gears. 75mph was 1450rpm in the big hole. But, the rears were so tall that to grab that last gear, you had to wind it out to the nuts, otherwise, the truck would fall flat on it's face.