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well this is what it looks like,,,,but its not this one,,,,,,,,but you might wanna find something closer to you ,,,,,i noticed your quite far from here,,,,,but this one has been in storage atleast 40 years,,that i know of and i dont know if the core leaks,,,or the blower works,,,bob

Leave the neck conected & sideload the beasts in the pic Removeing the neck is a slow process or fit a beaver tail to the RSend of the trailer cya

RTLO18918b has an extra bearing and different splitter gear design in the auxiliary section that the RTLO18913a doesn't have. If you put a 18 speed knob on a 13 speed and plum it up, the auxiliary will burn up the splitter gear in the 13 speed. Also, the main box ratios in a 13 is totally different than an 18.

If your going to run a lot of highway miles a steep O/D gearing is going to put a lot of engine power into heat in the transmission and rear axle. In an ideal world, you would have top gear direct and be able to get all the road speed you want. The world is not ideal, and for many reasons that is not easy to achieve and be usable. Most efficient is straight through drive, where all the gears are just "along for the ride" in top gear. Gearing up in front and down in back has lots of losses in the form of heat. It does allow smaller driveline to a point. That is why it was used of old. @Mark T is spot on about driveshaft speeds and critical rpm. It is easy to drive a driveshaft at speed that it will come apart. Shorter shafts and carrier bearing are required to keep the shaft from "whipping" at higher speeds. Spicer has a good online critical speed calculator.

Macks can be confusing in some ways. If you really look at any of those extended range transmissions with the ultra low gear and a huge overhear, they were pretty much made for how they came. Something like a mixer or maybe some dump trucks. Road speed wasn't their main selling point. Often they'd top out somewhere around a 300 and it'd be governed in the high teens (like @ 1900 RPM) Trucks with more of an on road personality might have higher horsepower ratings, but they'd never have been sold with the transmission and rears like the mixed service trucks. Mack also used to like using a higher numerical axle and a fairly high over gear in some of those ( like 4.64s and a .71 overhear ) Those koo koo low axles (like slower than 5.02s went with the extended range transmissions) If you ever looked at one, you'd notice they had a couple carrier bearings too. Gotta be careful how fast the drive shaft ends up spinning (like with a fast overgear) Lots of things changed as engines became more powerful in general, and those setups fell out of favor. Sounds like what you're trying to accomplish would require two speed rears. Pretty hard to get a truck that's best of both worlds without them .

It may be as simple as the 18 and 13 use different low (range) and OD ratios and if you got it to function, it would leave you with ratios that aren't really usable. A 15% splitter ratio for the 13 and 18% for the 18. So the 18 has a lower "low range" ratio so when in OD low it is close to low in the 13. If you take a normal 13 and add an O/D without changing the low range ratio you don't get the ratio spread you need to be usable.

I have Mack dm 686, am trying to find the part number for the twin tube air intake. Anyone has same series Please help.

always thought if adding an underdrive rear splitter 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.....