2018 Ram 6.4l Hemi Towing Issues

[Toddz]

I get what the dealer was saying about the trans not allowing the engine to rev up high in 1st, which is consistent with TFL's results towing 12,500 up the ike. That being said, the truck caps at 4,000 rpms if it doesn't have enough to shift to 2nd, where from what you said, your truck starts dropping below 4,000. I have towed right around that same weight all around the west side of the country and in when I dropped to 1st I was always able to maintain 4,000 rpms.

 

[Firebird]

Without going back through 14 pages of info, I assume 3.73 gears and stock tires? Then at least 4.10 gears would be needed. If oversized tires, then look at 4.56 or 4.88 gears.

 

[GsRAM]

Well I took my truck to the dealer yesterday to be checked out and was told there was nothing wrong. After further discussing what I was experiencing with the service manager and a head mechanic. The mechanic, who had over 30 years experience basically told me the 6 speed transmission is the issue. He said when going up a steep incline and the transmission down shifts from 2nd to 1st gear it will start off fine and then will go into what he called a 2nd purloin (not certain if spelled correctly) to protect the transmission. This is where the transmission will not allow the engine to over rev. He also said the transmission is really not suitable to handle the top end power of the 6.4 Hemi.

Since a Diesel is out of the question right now, I guess I have to stay out of the steeper hills. Other than the hills the truck pulls fine with plenty of power.

I am wondering if a transmission tune would held correct this issue?

If that's where your at, then your correct. I still think something is wrong. I don't think 9800lb is too much for our 3.73 geared trucks. Also, I call BS on the statement about the trans. The 2014 and newer ram trucks were purpose built HD trucks as was the 6.4 engine. There is no way any FCA engineer is going to agree the 66rfe was not built to take the top end power of the 6.4.

I'm sorry, that is a "we can't figure it out" excuse. With the way my truck pulls my tt, I just don't see it struggling with 10k like yours does. But I could be wrong I suppose.
More fuel for my fire that once you hit 10k loaded trailer weight, your in Cummins territory.

 

[Jversagejr]

I appreciate everyone’s replies and your helpful notes. As for the reason the mechanic told me, I am not certain if it was a Can’t Figure it out or Don’t Care answer. I guess I will either just have to live with it or get a newer one with the 8 speed.

 

[392DevilDog]

I can say the deal about first is true. There is only one hill here in PA that both my 8.0l V10 Magnum and the 392 HEMI have been tamed by.

It is on route 641 between Neelyton and Spring Run. It is one of those roads where you go up to the top of the mountain to just come back down the other side. Most vehicles can not maintain the post speed limit empty let alone towing.

Going southbound both trucks can do whatever you ask. No issue and all power. They both engine brake fine going down the steep side.

Going northbound, the one switch back is 10mph and you can not recover.

My V10 is coupled to a 5speed manual. So no transmission interference at all. Going south I pull in 3rd gear and just let it lump along and have no slow down with the switchbacks. With the Hemi I select third gear and coming out od the switchbacks the truck picks second but then back to third.

Going the other way...northbound...both trucks cruise right along in 3rd gear until the 10mph switch back. I can come out of it with a 2nd gear downshift with the V10 (I have done this a few times with the V10 only once with the 392) and the Hemi stays in third...but then the Hemi slams to 1st and the V10 has to be shifted to 1st...which is a granny gear..so that is fun.

Then the magic happens. Both the V10 and the Hemi will not make the shift to 2nd. The V10 because I know it will lug down and I am not about to miss a shift...it ia along way down the side til you hit bottom...and the Hemi because the computer will not let it. And to add insult to injury...the Hemi cuts spark as you hit the redline.

So...for whatever unknown reason...the computer does protect the truck from shifting. But I think it is more because of the ungodly distsnce between 1st and 2nd.

@dhay13 knows the road I am talking about. His son got to experience it not to long ago

Now I just take the truck route out around it and never have a bad thing to say about my GAS powered Mopar trucks.

I am not so sure our 03 Hemi 2500 could make the hill.

I have talked to some with the Cummins...the guys I know have always take the truck route.

 

[dhay13]

Yep. He said it was a pretty nasty hill. Can't remember the details he told me but did say it was a pretty good test

 

[Jversagejr]

Other than the issue on steeper hills the truck pulls fine with plenty of power. I am not certain why Ram designed a transmission to go into a safety mode that falls between 1st and 2nd gear basically reducing the power of the motor on a truck that is designed for towing. Well either way I guess as 392Devildog said, I will avoid the steeper hills and take another route.

 

[392DevilDog]

The other thing I dislike is that you can not lock out the down shift.

I wish you could select third at it wouldnt make a down shift like it doesn't make the upshift.

The 392 Hemi has similar power to the 488 Magnum...and I can tow with the V10 in 3rd gear and just modulate the throttle.

With the 392 as soon as you modulate the throttle you get the damn downshift to 2nd and if a hill is in sight right to 1st.

The 392 has enough power to do this in 3rd.

On our every other weekend trip to Prince Gallitzin camping...i have learned you have to get in the throttle before the transmission gyro notices you are going uphill and it seems to work just fine.

I wish they would have offered the G56 manual trans for the 392.

 

[Irishthreeper]

I have a ‘21 2500 6.4 w/4.10’s and we just towed our 5th wheel on a 7,000 mile trip, RV is prob about 10,500 loaded. Didnt encounter any issues at all. But a few years back I had a ‘12 Ram with the 4.7 and pulled a smaller camper (4800 loaded?) and had similar issues as you described. On long, steep climbs it would start losing power, RPM would drop and I was always concerned it was goi go to just quit on me. I think it had 3.55 gears?
Dealership had no idea what was going on and checked the truck out top to bottom.