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always thought if adding an underdrive rear box to an overdrive front, to make what Eaton finely did in the RTLO series. Gives you two O/D ratios .86 and .74, direct is one stick position down splitter in direct.

Let be start by saying I have zero experience with the newer RTLO series. All the roadrangers I worked on were the older RT-RTO series. I haven't been inside one in almost 10 years now 😮. I remember there being a reason the old series can't take a 13 and make it an 18 with just a knob change. So I am going to disappoint just about everyone including myself and say I don't remember why. There is no reason not to use highside low on a 9 spd or a 13 (or 18) where it becomes more risky is when you use the splitter gear. You are multiplying the input torque through the the front box, then passing though the splitter gearing, and it isn't designed for that. In direct the power flows straight through the back box. The reason it is not generally used in a 9 spd or others is it is a ratio in between 4th and 5th (or 3rd and 4th if you use the "low" terminology) and the step between that isn't a even step. If you're climbing a grade it may be tempting to use "funny gear" as it used to be called (highside low) but the jump down is a bigger one then it is to low side high, and it means any further downshift will also be another un-even drop. The low range gears are larger and better able to take the torque input for long periods than high side low. Empty I also have used funny gear many times, 1-2-3 (or if you must, lo-1-2) flip to high and go back to 1st, it is a bigger jump than continuing on in low and the jump from there to the next gear up is bigger jump than shifting as you "should". I only did it empty, not saying it is better or great but no harm will come. sorry not to remember better, a mind is a terrible thing to loose!

me thinks you are going to love the 300+ with the 13 speed. nice thing is you can also skip gears when running empty or light

Hello Heinzy.. 🍻

They hadn't dropped support entirely when I was there, but they certainly seemed to be trying to phase it out a little. For instance, your camshaft is likely no longer offered from Mack, but the lifters probably are. There didn't seem to be any rhyme or reason for what gets obsoleted like there is for Volvo, where I told customers that anything fifteen years and older would be tough to get parts for.

Flying Pig? Do you want me to see if I have the torque curve charts for youre engine ? If so, post what you have.. I am not smart about any torque curves and all the ratio stuff that is posted. Maybe I should be. Anyway. If I have specs you need I will post them.. Jojo

For many years I had been under the impression that all Mack engines had a torque curve that was flat as the great salt lake. In the mid 70s I ran an F model with 300+ and 5 speed. Legal weight at the time was 72000 (73280). I exceeded that with amazing regularity but the truck pulled it with ease. That what sold me on Mack power. Ive contacted a dealer to ask questions but an office retirement party stifled any call back. Im not here to argue but to learn. I understand that I need a lower rear end(I'll find out soon what Im dealing with) and that is why I want the lower gear and higher OD. Seller tells me it will do 70-75 down the hiway with tall 22.5s, which is ok as long as I can get around in the soft ground.

I have used that low hole 1st on the high side of a 13 speed many times.. Then split it!! It actually splits what would be 5th on the low side into 2 separate speeds which you need at the time.

Ok.. yep ,he will know. He should be here soon. I cant tell you how many times I shifted an Eaton 9spd Like a 10spd by accident, and it was fine.. Hell, what do I know? 😆

Yeah there was a lock out on the early 2130 you could grind off in the shifter to make a 2180 transmission. I don’t think you could do that with the fuller transmissions, Geoff will know. terry

13 spd.. my second guess. 😁 im curious... if it had a 13 spd shift knob, could it be used as such ? The Mack 2130/2180 is the same but the shift knob makes the difference.. years ago we called it a $65.00 upgrade to go to 18 spd. That was the cost of the shift knob with the gray splitter lever... if you took the shift knob apart, you could trim the red lever to work on the low side, if I remember correctly, seems like I have done that before somewhere..... GW? I expect a correction...

18913a. Go big or go home. I was looking for a 12513 but this came up reasonably priced local to me. Plus it is a real double over. Geoff, I did just rotate the body over 180* by the four bolts of the housing. I don't think I can clock it downward. Steering box was my first concern.

Too bad i didnt see this post hours ago. I may have been able to look at our set up and post pictures..

She's safe.....

Seems like if i remember the steel dash heater box, had the blower speed on a round switch on left side and heater controls coming out the top of heater box? terry

If your worried about spitting a driveshaft, you have the math backwards. Lets say you have 600 ft.lbs at the flywheel with the engine at idle, clutch engagement. If you have 12.57 low ratio, you have 7542 ft lbs into the driveshaft (assuming no losses in the transmission) if you have 20,08 low, you have 12048 ft/lbs into the drive shaft. In most cases you'll loose traction before you stall, front wheels sink in and the drive tires don't have enough traction to move you forward. Lower gear will not help with that. once the torque exceeds grip of the tires they will spin. Lower gears come in handy when moving heavy loads slowly, but if your tires can't grip enough, it doesn't matter. Soft ground it is all about what your tires can transmit to the soft ground. I did heavy haul and started loads of 170K with 12.56 low gear. backing that load in a tight space, a lower gear would have been handy, but risks the driveshaft if the operator isn't careful. Only way to increase reduction but not stress on the driveshaft is a lower rear ratio, either single speed, two speed or planetary hub. Superload prime movers use planetary hubs to lessen the strain on the driveline all the way to the hub.

Larry, you can take the 4 motor bolts out of the air starter, flipping the motor down low and re clock the drive. I don't know if that will give you enough wiggle room to get the motor out with the filter on, it will however give you a little more room on top to attach the large air hose. Not sure where your steering gear come to in relation to the engine, so that may be a problem.

It looks like an 8 LL