[nickboyer92]

I got a 39 foot toy hauler a few weeks ago and towed it home all flat ground and I was extremely impressed with the way the cummapart handled it. Handled most the grades in 6th gear, a few in 4th. I towed it in the mountains this weekened and had a hell of a time. When starting off shifts 1-2-3-4 are just so damn rough. I mean they shake the entire truck. Is this normal towing? It stays in 2nd and 3rd so long towing up steep grades I wish it would grab 3rd or 4th and drop the r's....

My next question, when in "tow haul mode" why in the actual f**** does the truck want to shift all the way down to 3rd while doing 65? I had a few instances when I was towing down a steep hill the truck would go form 6-4-3 and then back between 3-4-3-4 gear and make the most god awful noises red lining itself in 3rd gear. I need some custom tuning down to avoid these god awful shifts. Does anyone else here tow heavy and experience the same firm hard abrupt shifts?m

 

[N of 60]

#1) do you have the overdrive unlocked tuning?
#2) why are you trying to tow heavy grades in sixth gear, not good.
#3) what was transmission temperatures doing at this time.
#4) I tow quite a bit and I have never experienced what you have except abrupt down shifts going down hill with tow hall and EB on. I never used tow haul when descending for that reason. It pretty much wants to redline the engine. Climbing hills I have never experienced it. I always lock out sixth gear while pulling Hills.
I hope you get some good answers without costing you money.lol

 

[simplysmn]

What gear's are you running ?

 

[mikes3500]

I turn off tow/haul mode when going down long grades so it doesn't shift down when I don't want it to with the EB on and I can choose what gear is best

 

[nickboyer92]

I do have h&s overdrive. I'll get a custom tune wrote soon though. I have 3.73 gearing and with 35's I thought it still did well. What's the harm in pulling gradual grades in 6th if it doesn't downshift on it's own? I was seeing sustained 1250 on the EGT's while doing it. Nothing above 1300 really I know my truck ran that hot stock unloaded

 

[nickboyer92]

My trans temp was never over 140. Once I disconnected from the trailer the truck shifted normal. Are these what are described as "firm" shifts? My RPM's get high and it shifts hard and kind of throws you back in the seat and 3rd to 4th while the tc locks up it's just such a thud I can't help but think it's not normal? I just don't know how other peoples trucks react while towing heavy

 

[Duhameister]

My trans temp was never over 140. Once I disconnected from the trailer the truck shifted normal. Are these what are described as "firm" shifts? My RPM's get high and it shifts hard and kind of throws you back in the seat and 3rd to 4th while the tc locks up it's just such a thud I can't help but think it's not normal? I just don't know how other peoples trucks react while towing heavy

One of first things I learned with this truck is to not use the tow/haul mode with EB on decent or it does exactly what you're saying. The other option which I've done before on long downhill grades is to set the cruise control and the EB will come on as needed to slow you down.

 

[mikes3500]

He's talking hard shifts while accelerating, mine doesn't shift hard, no custom tunes here but I'm real happy with how it shifts. I've heard people complain about it and they all have trans tuning so it might be something with the programing. Maybe!

 

[SASdakota]

In my MCC experience with trans stuff. There are quite a few tables that will drastically change the feel of the transmission with very small adjustments... Plus lots of other cool features.

For example, 4-3 downshifts on its own in normal mode. (not t/h or manual ERS)

Best bet is to find a source for custom tuning and have it dialed in to your liking if you aren't happy with H&S OD stuff.

 

[Punisher 67]

One of first things I learned with this truck is to not use the tow/haul mode with EB on decent or it does exactly what you're saying. The other option which I've done before on long downhill grades is to set the cruise control and the EB will come on as needed to slow you down.

I have to agree with you on the tow/haul and the EB it can get almost violent going from gear to gear downshifting ....that is one combo I do not run . To
be honest I never use the tow/haul anyways and downshift manually downhills with the EB .

Nick I would absolutely NOT tow in 6th gear , I always tow in 5th and will drop to 4th on very steep grades always trying to keep rpm at around 1900 - 2100