Cat 3406E Question! MPG Poor at 3.5-4 mpg.

I'm deeply doubtful that you simply purchased a rebuilt trans and didnt have the core to exchange. Either that or you bought it from someone ignorant of what price those actually are.

If you had the core, that changes things a bit of course, but your claim of finding a decent one for 3k, still not really holding up.

 

My buddy got a deal on a “rebuilt” 13 speed. Turns out it was a single overdrive RTO instead of an RTLO that became obsolete in the early nineties. He was pissed about basically loosing 5mph on the top end. Good thing it’s just a dump truck!

 

turn the last two around

pretty sure I paid $1800 for the used rtlo 167 in one of our spare trucks a few years ago

 

well obviously I had a core. And I have a receipt if you don’t believe me. I could also give you the place I went and you could call and verify.

I clearly stated I paid 5k not 3k and it was a fully rebuilt one with a warranty.

Anderson Brothers Inc. | The Northwest’s Rebuild Center

 

Good deal!

 

Brand brand new was $7200 last I checked, would probably spend a little more to not have to worry about a reman or a core…

 

Sorry, somehow conflated you and cdemars, his contention was to throw away the 15 spd and put in a 13/18 for 3k, a 15 obviously isnt going to quite qualify for a 13/18 core even if someone will give *something* for it

 

The RTO 13/18 were #### in my opinion. You had to double walk the split button. Preselecting before moving the pole didn’t work out. The 15 was a better choice at that time not only a better overdrive but more reliable as well. Nothing is as forgiving as a 15. They just shift smoothly. Now I want to say I am referring to a 15715. I have never driven the 515 or 615. The ratios in them were different.

When Eaton went to the RTLO 13/18 transmission that made the 18 the most versatile trans on the market. The back box on both are actually an under drive. Being able to use that on the low side puts the 18 with the lowest low hole available in any transmission. 13 percent on every step to .73 overdrive. That’s hard to beat.
The 13 even though you have the button in direct to go to the low side it’s locked out and doesn’t use the auxiliary box in low. The rear bearing in the 18 is wider so it has a different case. The aux drive gear also has tapered roller bearings instead of bushings to handle the torque.


Not all 13 or 18 are equal. Many don’t realize they made an RTO15618B that’s ####. It’s still a half gear slow and problematic.

I have went from a 15 to an RTLO18913a. Any hill that I had to drop to 9th gear with the 15 I had to drop to 11th with the 13. They are both 1:1. My road speed at the top never changed nor did my fuel mileage. We was pulling the same loads across the same road all the time. Since the 13 was 6 percent more overdrive in the top hole that put my 65 mph on Kansas 2 lanes too low in high gear so I had to run 12th which is 6 percent lower than the 15. It was causing heat, as well as my RPM was higher than I wanted. Eaton doesn’t recommend running in direct for extended periods as the auxiliary will create heat. So my option was to go to shorter tires or regear from 3:36 to 3:70 since I had a good set of 3:70’s I did so. That put me back to where I was in high gear with the 15. Same hills same loads etc, still. No more road speed at the top, same fuel economy etc. still had to hit 11th gear on the hills that required 1:1 previous. I spent a #### ton of money there for no real return. Only way I gained road speed on them hills was add HP.

I’m only sharing my personal experience. Im a stickler for how my truck runs/performs. What RPMs we are at where etc. I expect alot out of it. Some are not as picky as I am. And if you start with 3:70 or 3:90 out back a 13/18 makes sense. I actually have landed at 3:55 on tall 24’s with .73 is right for what I do. That 150 rpm difference matters to me. My only point here is don’t expect it to end with a transmission. With 3:36 and a .73 on tall 24’s you’re gonna run 1500 at 80. Tall 24’s and 3.55 you gonna be at 1600 to 1625. With a cow bus in the wind that 125 matter. What your doing where your running most matter. Just an observation of an poor boy hoping to make it

 

2004 to end of 2011 and 2017-2018 I ran the northwest with 8 axles and a 15 speed. My old boss said they’re cheap to rebuild when he messes up and hires someone who couldn’t drive.

 

Good to know, ill keep that in mind as i look for an upgrade to my rockwell 9 spd, think i like an rtlo 13, but a 15 migbt work too if price is right