Question for owners of Ram 6.4l trucks.

wwt · 05-07-2016, 01:56 PM

I traded my 2006 Ram diesel for a new '16 Ram 2500 6.4l. We have a 24RBS Jayflight about 6000 lbs loaded. Our first trip with the new truck is this weekend and I'm already missing my diesel. We mostly traveled flat roads at 55 to 65 mph. The transmission never shifted into 5th gear with tow haul on.
Does this engine not have enough power to pull in 5th gear (high overdrive)? I know TH locks out 6th gear.
The truck has 3.73 gears so the engine was turning 2000 to 2500 while cruising.

I will say I like the acceleration better with this 6 speed Trans vs my old 4 speed.

Old skipper · 05-07-2016, 03:52 PM

Did you see if it shifted into 5 with the TH off? Try with cruise control off take it back up to 65 let off the throttle and see if it will up shift.

wwt · 05-07-2016, 04:03 PM

I did not try with TH off and I only used cruise about half the time.
I should also mention there was no strong winds either. Maybe 5 mph.
I'll experiment more on the trip home.

Seann45 · 05-07-2016, 08:11 PM

T-H should not prevent it from going into overdrive.. it just changes the shift point up by about 500 rpm

SmokerBill · 05-07-2016, 08:47 PM

Quote:

Originally Posted by Seann45

T-H should not prevent it from going into overdrive.. it just changes the shift point up by about 500 rpm

The tow/haul setting does disable the higher overdrive gear (#6) in my 2011 RAM. 4th gear is direct, 5th is the lower OD gear, which is enabled in T/H. And you're right about the shift point change. I just keep it in 4th gear at 2300 rpm and cruise along. Rarely downshifts, and the transmission stays cool.

wwt · 05-08-2016, 07:57 PM

Well, the trip home was a little more satisfying. I did turn T/H off and the transmission would shift into 5th. The truck seemed to cruise at 55-60 in 5th without struggling. It did drop to 4th on some hills. The problem with T/H off is if I eased off the throttle it would up shift to 6th and then back to 5th when I eased back on the pedal. I used the shifter buttons to limit up shifts to 5th and that seemed to work good.
I think I will get use to this new engine/trans quickly and it will do the job easily but it sure is different than the old diesel.

foxrider68 · 05-08-2016, 08:07 PM

My dad just traded his 2006 5.9 in on a 6.4 The main thing is to be aware of where a gas makes its power vs a diesel. I think the peak torque on your old 5.9 was either 1400 or 1600 RPM and on the gas engine its much higher. I would recommend you keep TH mode on, its not hurting anything and where the truck wants to be, or you could use the manual shift mode. Gas engines like to rev and theres nothing wrong with it but they will never tow like a diesel. However modern diesels aren't as good of daily drivers as a gas engine IMO either. Both have plusses and minuses and I think you made a good choice.

wwt · 05-08-2016, 08:18 PM

Yep, I understand the differences between diesel and gas engines as you said but I was thinking with 410 hp and 429 tq it would handle 5th gear a little easier than it does. I'm use to cruising at 1800 rpm and not downshifting.
I plan to use TH most of the time while towing locally but maybe on long highway trips I think 5th gear will work good.

oldmanAZ · 05-08-2016, 08:47 PM

Quote:

Originally Posted by wwt

Well, the trip home was a little more satisfying. I did turn T/H off and the transmission would shift into 5th. The truck seemed to cruise at 55-60 in 5th without struggling. It did drop to 4th on some hills. The problem with T/H off is if I eased off the throttle it would up shift to 6th and then back to 5th when I eased back on the pedal. I used the shifter buttons to limit up shifts to 5th and that seemed to work good.
I think I will get use to this new engine/trans quickly and it will do the job easily but it sure is different than the old diesel.

Thank you for posting your experience. Unlike you, few of us have towed with both gas and diesel virtually 'back to back.' You describing your recent experience towing with both is valuable to those struggling with the gas/diesel decision.

goducks · 05-09-2016, 12:21 PM

That's why I'd opt for the 4.10 gears. You don't need TH when just cruising down the road. Stick it in 5th and settle in. TH will make the tranny more nervous and want to shift down sooner. With my Ram 2500 CTD I only use TH when running thru town or accelerating. I turn it off when in the mountains or on the hwy. I prefer to shift myself with the +/- button.

sugarray · 05-09-2016, 12:51 PM

I have towed 1 season here in the mountains of WV. I use T/H anytime I hook up. Seems to deliver better torque. I have the 4.10 gearing though. I have towed to Niagara Falls and back and no problems. I routinely see 5th gear and on a flat stretch will cruise in 6th. I use cruise as helps to keep speed under better control during a descent. I run at 64 on the highway.

goducks · 05-09-2016, 12:53 PM

Sounds like the 4.10s work well with the TH mode. Good to know.

Tgallagher · 05-09-2016, 08:56 PM

So far I've only made one trip with my 6.4 and the RV. I do have the 4.10 gears. I am very happy with both towing and as a daily driver. No doubt it's not like the other Cummins I've owned pulling, but I knew that going in. It is pretty dang good though. When it finally does downshift into fourth climbing a hill with the cruise set, it opens up and goes to town. Very good riding and comfortable truck. If you're not towing all of the time, I would recommend it for sure.

15BlueStreak · 05-11-2016, 08:46 PM

This has been my experience with truck not shifting into 5th. I will set cruise say 3-5 mph higher than I want. Then hit decel button to desired cruise setting. This will make it shift to 5th gear then. I like running tow haul. I believe it also increases fluid pressure in tranny which helps in the firmness of shifts. I could be wrong though.

jsallman1 · 05-12-2016, 02:22 PM

I havent had it on the interstate yet but my 2015 6.4l with 3.73 gears stays in 4th short of a real down hill no accelerat highway speeds (55) with tow haul on and at around 2000 rpm. Tow/haul off it shifts i to 5th much more easily. Taking a 3 hour trip tomorrow with it, first long trip with this TV at 60-64mph, Will let you know if I see the same experience

wwt · 05-12-2016, 08:11 PM

Quote:

Originally Posted by 15BlueStreak

This has been my experience with truck not shifting into 5th. I will set cruise say 3-5 mph higher than I want. Then hit decel button to desired cruise setting. This will make it shift to 5th gear then. I like running tow haul. I believe it also increases fluid pressure in tranny which helps in the firmness of shifts. I could be wrong though.

Good to know. I'll try that next time.

wwt · 05-12-2016, 08:25 PM

I hope I didn't give the impression that I'm unhappy with the truck, I'm not. The more I drive it the more I like it. If I could do it over though I would get the 4.10 axle. The tires are 33.5" which are 2 inches taller than my old truck which had 3.73 gears. I think the 4.10 would make up for the taller tires. I still got 10 mpg towing which is what my diesel got.

doo800XRS · 05-13-2016, 05:49 AM

Fwiw I have the same camper but different truck.. I tow with a 02 Chevy 2500hd 6.0 gasser with 4.10 gears. It tows amazing. It doesn't hunt for gears goes into overdrive.

I have now added 33" tires and it put my effective gear ratio in the 3.8 range. I noticed a pretty big change in how it pulls.. still does very good but you need more throttle than before. I use T/H mode and it still hit's OD but it shifts down quicker on longer inclines. If I do any long towing where there is alot of hills I switch to my smaller tires and wheels to get my 4.10 ratio back.

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