Rear ends and transmission compatabilities

I have a 1999 Freightliner Century. It has a N14 and a direct 10 speed and 2.79 rear ends. I love my fuel mileage well it could improve some but its ok. I get 6.0 and i pull a flatbed and haul long and heavy stuff. I go weekly from Oregon to LA and bk so i am loaded both ways and am always pushing the 79000 mark. I can legally haul 51500 at 80000. I like my flat road speed but want a lil more on the hills. I have been told a 14613 transmission would probably be what i want. Any input? I found a 15613 transmission for $2500 just want to make sure it gives me a little bit of options on the hill and still good fuel mileage. Also my truck will derate me sometimes to 1500 rpm when pulling a hill. It gives me a code that says engine road speed and wont keep record of anything ever. If i pull over and shut it off for a few minutes it resets the compiter like nothing happened and off we go. Some say its a failing ecm. What do you think? Cummins wants $2500 for a new ECM, ugh!

 

A 14613 is a single overdrive transmission, where the top hole is .86 to 1 and 12th is direct 1 to 1. A 13 or 18 would help in the hills, as with the splits, you will be able to stay in the peak power and torque bands, better than that 10 speed. The other problem could possibly be the speed sensor, on the tailshaft of the transmission, loose or failing. Although, that ECM is 13 years old and may be going down. It's electronic and electronic things fail, some rather quickly, some not so quickly, but after 13 years, I wouldn't complain.

On your route, you aren't able to legally go very fast, as Cali and Oregon are both 55 speed limits for trucks and lots of hills. I'd dump those 2.79 gears and go with a lower ratio, like 3.55 or maybe 3.70. See what Anderson Bros, in Portland has availible. I've been running a pair of their rebuilds for over a half million miles, with no problems.
Sitting here thinking about this, I'd go rears, first. Then think about going to a 13 or 18 speed.

 

I agree. I already put 2 new speed sensors. But i am debating sending my ECM in to get rebuilt. I have no problem switching rear ends as long as i still get fuel MPG and can go 65 or so with decent rpms.

 

I used to live in Oregon, there is nowhere in the state, or in Cali that you can run 65 legally. Slow down to 60 or below and with the proper gears, your fuel mileage will make a good sized jump. That will put a good amount of money in your pocket, every week and make very little difference in your time driving.
BTW, I had Jake and his boys, at Pacific Truck and Trailer, in Vancouver WA, do the swap. Good work and a fair price.

 

Thank you. There is an Anderson Brothers on Eugene that i have been discussing it with as well.

 

Yea, pretty sure that is a branch of the Portland yard. Like I said, no complaints of their quality or prices. After a half million miles, they haven't fell out, on the ground, yet.
There should be some good independent shops around Eugene, that can do the swap. As to the ECM, may just have to bite the bullet.

 

Ok thanks.

 

DO NOT go to anderson bros in portland they use chinese gears.... fail quickly

 

psst i live here too (mt hood area)

 

Dang, think I should be holding my breath, after 9 years and over a half million miles?