Tractor First, Right?

Im fairly certain all 9 speeds can become 13speeds by putting on a 3 speed auxiliary box.

Call trevor at betterbilt transmission on rocus st in springfield. Been a roadranger rebuilder all his life.

What kinda shifting tips you looking for?

 

If you put the RTO 14613 rear box on that transmission you will end up with a .62 overdrive. With the 4.11 rears that may not be a bad thing. Most refer to that set up as a double overdrive. Though it actually has 3 ratios above 1.1 or direct. Due to the rear being an overdrive and not and underdrive, they will try to heat in a pull if left in overdrive on the knob too long. Keep in mind eaton improved their lubrication tremendously since the 6 series was produced. Don't let the above scare you away from it or cause you to spend money for no reason. I ran one for years with minimal trouble. No longer than you stay in each gear running up through them even loaded heavy you will be fine. Running with selector in overdrive for extended periods up to about 70k gross should be ok. If loaded heavy pick a gear on the direct side as your cruise gear.

 

The auxialliary section is the "back half."

So youve got your main box. Reverse and low hole on one rail. First and second on the middle. Third and fourth on the other. Thats 1R and 5F gears in the main box. The auxilliary has a reduction gear (low range) and a high gear (direct). That gives you 2 reverse and 10 forward except low hole isnt to be used on the high side on a 9 speed. Some say its not strong enough but ive been in a few RR's and cant see how its any weaker. The issue IMO is it doesnt match the shift progression to the next gear. So this is your "nine speed" .. Its a 5speed trans with a 2 speed rear except the 2 speed is in the tranny back half. About 500rpm steps per gear.

13 speed has a 3 speed "rear." 3rd gear in the aux box is only useable when in high range, and it gives half a gear difference than direct. I think theyre all overdrive, not certain. This means the top 4 gears can be climbed in half steps.. So you have 8 gears on the high side. You can go from 5 to 6 or from 5 to 5-1/2 so to speak.
It makes a huge difference especially in hills, think of an elderly woman climbing steps. Fewer the steps harder she has to work to get upstairs. This 3rd range gear is the "splitter." Low hole on the high side can physically be split also but again its taboo. I do it all the time in my medium duty but what do i know.

An RTOO does indeed have three od ratios. 7th under is direct and the most efficient gear. Power flows straight through at a 1:1 input to output speed. I believe the front box countershafts are overdriven as well as the mainbox top gear (on mine its against the dash, "U pattern")

Dont do the 4 / 5 gear flip in the main box to get an OD like old schoolers did. Itll mess up the shift spacing at the spot where you really need a seamless shift to maintain all the speed you can on rolling interstate hills.

I run an RTOO 1.0/.86/.74/.62 with 4.63 rear and 37" rubber and its great, loves interstate. Has low like an 8LL and still goes 80 not even close to governor. But again, medium duty, i gross 45k or less and im always in mountains. They do whine a bit more.

If youll be taking 8 south to 84 theres a good hill out of waterbury right at the onramp. Not too bad otherwise, just a lot of tolls in NJ.