Correct way to level 2014 Cummins 2500?

[Buckfat]

Zone off-road makes a offset spacer to correct this situation.

 

[Klaus96]

They have offered to "fix what is there" or for $350 out the door they will intall the Rancho leveling kit which consists of shocks, coils, swaybar drops, locators etc..etc....For the price I will probably jump on it. Cheapest I can get the Rancho kit delivered to my door is $500 so it sounds like a good deal.

 

[SouthTexan]

Correct way to level a 2500 Cummins?

Do what it is meant to do and put a 13k trailer behind it.

You see, perfectly level.

 

[Mega-Hemi]

Not to nit pick but a 13k lb 5er is maxing out your payload before the driver or any gear.

 

[SouthTexan]

LoL... payload. I don't go by the factory payload numbers and neither does my states law enforcement. I go by my GAWR because I know my trucks payload is purposely decreased to fit it in the GVWR class it is in and nothing more.

 

[Klaus96]

Correct way to level a 2500 Cummins?

Do what it is meant to do and put a 13k trailer behind it.

You see, perfectly level.

Nice! Off topic question, we were talking at work about replacement transmissions. One guy thought there was an adapter plate to bolt up an Allison. What options are there, if any?

 

[SouthTexan]

Nice! Off topic question, we were talking at work about replacement transmissions. One guy thought there was an adapter plate to bolt up an Allison. What options are there, if any?

No worries. You are the OP of this thread so you are allowed to steer the topic any way you please as far as I am concerned.


As far as the Allison, I think it is more of a matter "bolting up" with the new electronically controlled transmission compared to the old days. You would have to program the transmissions comtrol module to work with the Cummins and its power band. I am not saying it is not impossible, but it is definitely more involved than just "bolting up".

Although the 68RFE is almost identical in gearing, clutch count, and clutch size to the Allison. In fact, it was mirrored after it when the built the 68RFE. I think the Allison may be able to take a little more abuse and better shift programming, but the gearing in the 68RFE is a little bit better.

6RFE
1st: 3.23:1
2nd: 1.83:1
3rd: 1.41:1
4th: 1.00:1
5th: 0.81:1
6th: 0.62:1

Allison
1st: 3.09 : 1
2nd: 1.81 : 1
3rd: 1.41 : 1
4th: 1.00 : 1
5th: 0.71 : 1
6th: 0.61 : 1

 

[Klaus96]

I see, thanks! I don't care for the shift points in mine. Seems to hold on way to long when slowing down.

 

[SilverSurfer15]

not to go too far off on this, but you know the Allison 1000 really isn't the be all end all trans. They have plenty of problems, which is hard to sometimes find through the constant "everything GM makes is NASCAR spec Military grade in your face pure BAMF" nonsense but its true. The Ford 6r140 is really the best stock diesel trans going on right now. Except for allegedly the 15-16 models are weaker than the 11-14 due to less clutches, but that hasn't really seemed to be proven yet. They make 600whp pretty reliably and H&S beat the crap out of one and it was still ticking. Its pretty well known that 500+whp on the A1000 is a time bomb.

that being said, the 68rfe doesn't seem to be that bad now days with a few simple mods. All three of them will self destruct if you get too wild in the O/D gears, so theres really no getting around that.

You just need some tuning to raise the pressure, converer lock up, and move the shift points around. Night and day difference.

Also, my .02 on these newer trucks is that 3.42 is a ridiculously tall gear even stock. So adding a taller tire and now its even goofier. I realize no one wants to pay for a gear swap, but I think the results might blow some peeps nips off with 3.73s/4.10s (and since they make OEM cuts in those ratios, even better)

 

[SouthTexan]

I will admit that there was a time when I first got my truck that the 3.42 gear was too tall of a rear gear. After towing my 13k RV, 10k (loaded) cattle trailer, and various other trailers, I no longer think that the 3.42 is too tall. Especially when I compare it to other friends that have 2010-2011 650 lb-ft Cummins with 3.73's. My 800 lb-ft Cummins with its 3.42 gear sends more torque to the tires in every gear than the 2011 650 lb-ft Cummins with 3.73's.

Ram 2014 2500/3500 6.7L CTD 800 lb-ft @ 1,600 rpm with 68RFE with 3.42 rear ratio
1st gear--3.23: 2,584.00 lb-ft x 3.42 = 8,837.28 lb-ft
2nd gear--1.84: 1,472.00 lb-ft x 3.42 = 5,034.24 lb-ft
3rd gear--1.41: 1,128.00 lb-ft x 3.42 = 3,857.76 lb-ft
4th gear--1.00: 800.00 lb-ft x 3.42 = 2,736.00 lb-ft
5th gear--0.82: 656.00 lb-ft x 3.42 = 2,243.52 lb-ft
6th gear--0.62: 496.00 lb-ft x 3.42 = 1,696.32 lb-ft

Ram 2011 2500/3500 6.7L CTD 650 lb-ft @ 1,600 rpm with 68RFE with 3.73 rear ratio
1st gear--3.23: 2,099.50 lb-ft x 3.73 = 7,831.14 lb-ft
2nd gear--1.84: 1,196.00 lb-ft x 3.73 = 4,461.08 lb-ft
3rd gear--1.41: 916.50 lb-ft x 3.73 = 3,418.55 lb-ft
4th gear--1.00: 650.00 lb-ft x x 3.73 = 2,424.50 lb-ft
5th gear--0.82: 533.00 lb-ft x 3.73 = 1,988.09 lb-ft
6th gear--0.62: 403.00 lb-ft x 3.73 = 1,503.19 lb-ft


Not only that, but the 3.42 also puts you right in the beginning(1,850 rpm) of the 1,800 to 2,100 rpm in 5th that Cummins recommends for the best efficiency when towing at 65 mph. Even increasing my speed to 70 mph I am still within that range at 2,000 rpm. Not only is by buddy's 2010 5th gear sending less torque to wheels, but at 65 mph he is a little over 2,000 and at 70 mph he is past the efficient towing range at 2,200 rpm. So I got effiency and more torque.

I know a lot of people think the off the line performance of the Cummins has to do with the 3.42 rear gear, but if you tune it taking out or reducing the torque management then you will quickly notice that it is the torque management and throttle lag making it slower of the line, not the rear gear.

 

[SilverSurfer15]

good info, and you are right. it probably is the best gear for a stock towing set up.

I still think since most people toss on 35s and a level or more, and just want to cruise in 6th on the highway, rarely towing much more than 6k lbs 5x a year, the gears could be a huge gain. at least the way I see the marketspace, it all depends on what you are doing I suppose.

 

[Klaus96]

All good info guys. How about something simple as I figure out my Cummins? I've only had it 4 weeks. When empty, what rpms are ideal at various speeds up to 80 mph? Seems 6th at 60 is ~1300 -1400

 

[SouthTexan]

It just depends on how much horsepower and engine load is needed to move your truck down the road. When empty on a flat surface, you don't need that much horsepower to maintain speed so there is not much load on the engine. In this case you want the rpm's as low a possible to the exact amount of horsepower needed to move your truck to get the best efficiency.

 

[SilverSurfer15]

yea there are a lot of variables but ill just toss out some opinions.

1) don't do 80 if you want to see decent MPG. About ~65 is probably going to be the limit, the faster you go the worse its going to get.

2) generally, best highway rpm is around 1600-1800rpm (which goes back to my gearing statement)

3) 1300-1400rpm is too low for hwy speeds. going to bog and boost or downshift.

4) maximum economy will come from the lowest RPM where you aren't lugged down or over revved, and are producing as little boost as possible. Basically what southtexan said. Its not different than a gas motor, just because it has the ability to create huge tq at ultra low rpm, doesn't mean doing so is good for fuel consumption. Which I think some people get wrapped up in this concept.


again these are my opinions, also I'm giving this opinion from a FL perspective. Sea level and no elevation. In other parts of the country, it would be different.

 

[SouthTexan]

I don't think 1300-1400 is too low fr the Cummins when you are unloaded. I travel about 10 miles at 60 mph down back roads every day to work (41 miles one way) at just under 1300 rpm. It holds speed on the flats and the few hills I have a long the route very well without any sign off bogging down or down shifting. Only time it gives a hint of struggle is if the DPF back pressure is getting to the point it needs to regen. If the DPF did a regen in the last 40 miles then I can easily hold speed at 55 mph (1175 rpm) on the same route without any sign of struggle from the engine.

When I start getting bellow 1100 rpm on a clean DPF with little back pressure, then the engine will start to bog down and need to down shift on the hills. The closer I am to needing to regen, the higher the rpms I need to keep from bogging down. I imagine that a deleted Cummins can easily hold 1100 rpm in 6th on my commute without bogging down.

 

[Klaus96]

What about this? When coming into town off the highway and eventually slowing down at an intersection my truck will hold 5th to under 35 mph, which is fine unless you are speeding right back up from 35 mph, then it sounds luggish.

I just want to be sure the trans operates correctly, I'm still butt hurt about my 99 1/2 ton that the tranny went out on at 54,000 miles.....lol

 

[brandonjansen]

Coming back to the suspension side of this thread... What your springs are doing is very normal for a radius arm truck with a spacer level. There are companies out there making offset spacers which help the springs bow less, but they still bow. The best way to get rid of that is to ditch the spacers and run a full leveling spring. I highly recommend Thuren's progressive rate springs, Fox shocks, and adjustable track bar. That's one of the best setups you can run to level your truck and you certainly won't be disappointed.

 

[Klaus96]

I'm all over the Thuren stuff. I have been in comms with Aaron at Thuren. I'm in a situation with the dealership on this one as they are willing to fix my level, but obviously they won't scrap my crappy spacer set-up and spring (no pun intended) for a decent set-up. They have been using Rancho coil levels with good luck. I did bring up the fact that Thuren recommends an adjustable track bar with over 20k miles on the truck. The shop guy was going to talk to the techs today (haven't heard from him yet) and see if this would apply to the Rancho kit (I imagine it would). Maybe I'll see what they can do with pricing out a complete Thuren set-up.

I have Fox 2.0's on there now, but I can't find a part number on them to see if they'll work with the Thuren coils. Hate to toss em if they will and its another $300

 

[Klaus96]

I've been asking about rpm's and shift points because I'm going back to the dealer for a rambox switch replacement and thought about asking to change shift mapping or flashing.

 

[Juvenator93]

2 1/2 Rough Country level kit. Spacer is angled to accommodate the new radius arm coil set up. Like it a lot so far. Came with shock extensions to allow use of OEM shocks.


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