2015 2500 6.4 towing/trans experience

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Snyd

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What gear ratio is your truck? I can't for the life of me figure why any dealership would order one of these WITHOUT 4.10's!! For crying out loud..... 33inch tires and 2 overdrive gears and they neuter the thing with 3.55's. I ordered mine with 4.10's. Took an 11500mile 2 month road trip last spring from Alaska to the lower 48 and back. Every condition you could imagine. Granted, my TT is only 5000lbs but is very tall and boxie. Quite a big sail. I never used tow/haul mode other than to try it out. I did use it on a few long down hill grades but soon realized it was not any help. No need to use it. All it does is hold the tranny in a lower gear for longer and to keep the tranny from hunting for a gear and heating up. I think the owners manual spells that out. Turn it off, put it in "D" set the cruise and let her fly! I love my 6.4 4.10 truck.
 

Blazin383

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I tow my 7500 lb boat with my 2015 2500 with 4:10 gears and so far it has handled every situation with ease. Granted a 7500 lb boat isn't a 14,000 lb 5th wheel with the surface area of a barn, but I've never had an experience with double gear down shifts on downhill grades, or any problem with the truck not finding the right gear on a steep uphill etc, and I always use Tow/Haul when towing.

Maybe my load happens to be the sweet spot for this trucks towing capabilities, but aside from just being thirsty (7.5 - 9.5 mpg), I've never felt like the truck was under powered or under geared for my needs! As for the suspension and stability while towing, the truck is a dream!
 

tjfdesmo

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Sorry to dredge this back up, but I am wondering if there is something wrong with mine. Can anyone with a 6.4 66RFE confirm that it will shift into 5th gear when in Tow/Haul? Even empty, mine just revs out in 4th.
 

drittal

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In tow/haul my 6.4 would go into 5th, never 6th


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mtofell

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Sorry to dredge this back up, but I am wondering if there is something wrong with mine. Can anyone with a 6.4 66RFE confirm that it will shift into 5th gear when in Tow/Haul? Even empty, mine just revs out in 4th.

My 2014 6.4 66rfe will definitely shift into 5th at times with my 11K 5th wheel in tow. Granted it's not often and usually involves some kind of down hill. Also, it usually lugs pretty bad in 5th so I often just lock it in 4th manually. Honestly, unless I'm on a flat interstate I shift manually. I swear 90% of the time I'm towing I'm in 2nd or 4th gear.
 

loveracing1988

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Sorry to dredge this back up, but I am wondering if there is something wrong with mine. Can anyone with a 6.4 66RFE confirm that it will shift into 5th gear when in Tow/Haul? Even empty, mine just revs out in 4th.
With an empty truck it will go into 5th but towing pretty much anything and I never see 5th.
 

monteholic

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I can get into 5th empty, 5th is also an overdrive gear so loaded you will rarely ever see it go into 5th
 

jaflowers

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My one tow was from Durham, NC to Colorado Springs, CO. I wasn't heavy but had roughly 1,200lbs in the bed and a 7,500 trailer. My first day was almost exclusively in tow haul mode and I saw 5th frequently. I was still new to the truck and by early the second day I didn't use tow haul much, I'd see 6th on the flat stretches and 5th-4th on uphill areas. 6.4 with 3.73 rear.
 

sandawilliams

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ok, so this horse has been beat to death. the transmission is less than ideal. I've had such a miserable towing experience this week, I gotta ask. Is there an easy way to check for an update for the transmission factory programming? will the dealer let me know if there's an update?

This week, we took the 9000 lb travel trailer from Sacramento to Santa Barbara. Was in tow/haul mode the whole time. So, going over the mountains going UPHILL, the truck held onto 4th gear forever and wouldn't shift into 5th unless I actually slowed down from 55 to 50 or less. then I would have to very slowly build up speed again just so it wouldn't shift back into 4th. Ok, maybe not a big deal.

The bigger issue was going down hill. I assume these trucks have an incline sensor. down even a mild grade, touching the brakes immediately sends the transmission from 5th to 3rd at 55-60 mph. even with gentle roll on throttle, it won't shift out of 3rd. Add to this, if you even tap the brakes a second time, it shifts into 2nd, holds it until you hit a flat/level area. This means you are near redline, engine screaming, the entire way down the hill (6-10 miles long in this case). I tried switching out of tow/haul. nothing. I just had to slow way down and ride out the hill in 2nd until I hit bottom.

is this considered normal? anyone know of an update/flash?

I have the same problem. I have towed over 20,000 miles now and here is what I have come up with. When conditions allow I take my truck out of tow/haul and manually put it in fifth gear. This allows the truck to run at 2000 rpm at 65mph. When approaching terrain that will bring the rpms down I manually shift into fourth. If I had been in tow/haul at this point sometimes it makes the fourth to second shift that really ****** me off. I do a lot of mountain driving (Colorado) and that is all in tow/haul because it changes the shift points and seems to do a better job than without it. Going down I am always in first or second to keep the truck/trailer under control and only touch the breaks when additional breaking is needed. Just a suggestion.
 

Andrew09HEMI

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So you guys use tow/haul even when not towing? My experience this past week with very little weight, maybe 3k? I used tow/haul in the city and it shifted to 5th for sure but this is nothing like you guys are hauling. I'll try using tow/haul today unloaded and see what it's like but I can't imagine holding gears that long would be enjoyable.
 
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reek

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I have the same problem. I have towed over 20,000 miles now and here is what I have come up with. When conditions allow I take my truck out of tow/haul and manually put it in fifth gear. This allows the truck to run at 2000 rpm at 65mph. When approaching terrain that will bring the rpms down I manually shift into fourth. If I had been in tow/haul at this point sometimes it makes the fourth to second shift that really ****** me off. I do a lot of mountain driving (Colorado) and that is all in tow/haul because it changes the shift points and seems to do a better job than without it. Going down I am always in first or second to keep the truck/trailer under control and only touch the breaks when additional breaking is needed. Just a suggestion.

flats and up hill, I have very little "issue" with the truck. My original post was an observation of the uphill shifting characteristics, not a true concern. And like a lot on here, I do occasionally shift manually for UP hills, etc.

The part that scares the crap out of me is going down hill at almost 6000 RPMs in 2nd. several on here tell me it's fine but I plan to keep this truck for a long time and I just can't imagine prolonged 6000 rpm runs would help me do that. Hopefully I'm wrong to worry. newer engines are amazing but physics is physics.
 

Iron Outlaw

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6000 rpms is 6000 rpms. My truck has done it one maybe two times. If it did it alot I would be worried about it. It's a work truck and I need it to last a long long time and haul a lot of stuff.
 

smurfs_of_war

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When I read some of these stories I keep thinking about a couple of our old grain trucks with the "industrial" big blocks that have spent pretty much their entire lives of 40 plus years at or near redline with payloads that would crush one of these trucks flat. I'm not too concerned about a few RPMs ;)

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