Stock 03-04 48re 4.10 towing rpms

[JohncJordanIII]

So I am looking for those who have or had 03/04 3500s with 48re, 4.10s, SRW, stock everything including tire size for reference on rpms for towing less then 5k to 15k.

I picked up my inlaw 9,990 gvwr dump trailer. With high side boards it may weigh 3,500 empty give or take. I guess I'm not used to the 5.9 305hp with 48re and my expectations were to high. Coming home I got some steep hills where Semis crawl with hazards. I have a scanner hooked up for data logging as I'm a OCD diesel mechanic with Class A CDL and drive 18 speeds and very proud of rebuilds and in-frames in my life. Everything checks out perfectly per Cummins. But I guess I wasn't expecting to give 1/4 throttle to almost half maybe at 2300 RPM or more to get a unloaded 10k dump trailer moving up steep hills at posted speed limits from a dead stop. Granted there freaking steep like I would lose my breath walking up them and when 3rd lock up kicks all is cure then 4th lock up is money. Just curious on feedback. I know these TC and VBs need attention from the factory and again my personal tow rigs and dailys all gas so I may just be unfamiliar with this generation too and be dumb when nothing is wrong as this is my first diesel pick up truck and I'm spoiled from 18 speeds and vessels with 2 or 4 diesel engines

 

[petersonj]

It sounds like you are describing a perfectly normally operating Cummins powered stock truck with an automatic transmission. Your description of how your truck performs is precisely why my truck has a 6 speed manual transmission. I think you are already dialed in on how well manual transmissions make a diesel engine perform based on your truck driving experience.

The truck you are describing has only four forward gears with one gear being and overdrive gear. Combine that with a stock high stall speed torque converter and only two converter lockup gears (3rd and 4th), the engine rarely operates in its peak torque rpm range when accelerating from a stop.

There are modifications you can do to improve the transmission performance, but in the end it is still an automatic transmission with four gears. Others will probably chime in to help you with deciding on the best performance modifications if you choose to go that way.

- John

 

[JohncJordanIII]

Yea I kinda kick myself for not having a manual but finding one one unmolested with records and stock with low miles is hard. But I like it enough I'll spend the money and upgrade the transmission.

 

[cerberusiam]

Starting from a dead stop you are in fluid coupling with a stock TC that is MAYBE 70% efficient at transferring power, of course it is going to take some throttle and time to get up to speed. That 10k dump trailer even empty may just pull hard and on a grade that steep it shows in the stock trans operation.

The trans needs some upfitting, the engine needs some tuning. THEN you can smile all the way up those grades.

 

[JohncJordanIII]

I actually loaded it to completely. Trailer was about 9800 full per scales, about 1k of tonque weight per my weighsafe hitch guage, my heavy canopy and loaded the bed full to the top of 4x4 pressure treated timber. I tackled every hill I can find and just kinda played with throttle and what not. I think alot of it just not used to it. Highway it's great even on a steep pass, I found speeds below 45mph I use manual second, OD lockout and that helped alot. After not baby the truck easy on the throttle and drove it like my fire trucks where it's half throttle at least with the Allison's it really made a difference. And made me happy. Granted I burn fuel in a day playing clocking 300 miles towing but now that I experimented I feel a whole lot better. I love manuals but love how the 48re has such a strong following for parts , I get to drink coffee, hold my wife hand and smash tacos with heated seats so I'm happy. I still got better MPGs then my 6.0 Silverado empty, my lifted 5.3 Silverado and my dad's 2013 f150

 

[Ozymandias]

You are doing good, the 48 need some time to get used to it, gow to handle it.
For example 2th manual gives you lockup in 2th gear.

Also the addition of an EB changes the shift logic and lockup logic if activated.

 

[JohncJordanIII]

I honestly prefer this 48re over Allison's I delt with in duramax and the 7.3 autos. Never drove a 6.0/6.4 auto so can't speak for that. What I do like is when this transmission goes atleast stock parts are not expensive and they seem fairly simple for rebuilding as long as your paying attention and stay within specs using right tools and what not.

 

[Ozymandias]

Yep, aside from the lack of two gears that gives us that HUGE jump from 3 to 4 it is a fine transmission, easy to maintain and durable.
But you with the 4.10 are good at this place, your jump is smaller then mine with the 3.73 AND 35er Tires. Just because of this I'm going to 4.30 gears next month.

 

[sojoe]

lotsa 5.9/48re pulling heavier rv`s with no problems...…………...

 

[JohncJordanIII]

I personally wanted 4.10s becuase of the hills and mountains here in WA state. My in town mpg is about 14-16 so I'm really happy this thing a prius compare to my gassers work trucks. So I guess my next question since we're on the subject is the owner manual says it's fine I think but for those that know the 48re inside and out can I manually shift it like a push button Allison without harming it? Under 45mph I enjoy manual 2nd, then D/3rd OD off, then after 3rd lock up I'll tap the button and let 4th sink in. Thanks again this forum is awesome!

 

[Ozymandias]

Yes you can, no problem with that.
The trans will not downshift if the actual speed is to high for the desired gear.

Its even better for heavy pulling if you shift manual to second instead of let it downshift in D to 2.
Has something to do with how the valvebody works, manual 2th can take more load then in D.

Also shift manual to first if you feel the need for it, on itself it will almost never shift down to first.