[mikoz]

how to make the "6 speed" transmission in 2012 Hemi actually work as a 6 speed?

Hi,

I have a 2012 Overland with Hemi. When I bought the vehicle, I was under the impression it was a 6-speed (as opposed to a 5-speed in MY2011). However, it seems that the transmission can't select from all 6 gears unless you manually do it yourself. The manual does state that to access all 6 gears you have to use ERS.

I find this hard to believe. And, I find it harder to believe that there's no program that allows you to have access to all 6 gears unless you manually switch the gearbox yourself and you've memorized the table that lists the gears available per mode which is documented on page 448 of the owners manual.

A few questions....:

1. for highway driving (economy at high speeds), doesn't it make more sense to be in "6" which gives you gears 1,2,4,5,6 instead of "D" which gives you 1,2,3,4,5?

2. how do you make the vehicle default to "6" which gives you gears 1,2,4,5,6? How do I make it such that the vehicle is setup to use these transmission gears without manually moving the gearbox to the right every single time I shift into D?

3. isn't it really incorrect advertising to claim it's a 6-speed transmission? 99.999% of consumers would assume that if you tell them it's a x-speed transmission it means that gears through 1-x (inclusive) are all available with the default "D" (or perhaps Sport setting, if applicable) program? It's sort of like advertising that a TV supports 1080P resolution only to find out that if your source is 1080P you have to know that ahead of time and switch the mode in the TV manually to support it which then locks out some other resolutions.

4. what is the technical reason why there's no program for the transmission that supports switching the of gears 1-6 without user intervention?

Thanks.

 

[myoung84]

Re: how to make the "6 speed" transmission in 2012 Hemi actually work as a 6 speed?

It's all Marketing. Plain and simple.

Shifting from 2nd (1.67) to 2nd Prime (1.50) is pointless. When the 45RFE was designed (As a 4 speed), 2nd prime was intended as a kick down gear only and was never intended to be used as a normal upshift gear. Through some clever programming, they gained a 5th gear when they put it behind the Hemi trucks in 03 and renamed it to a 545RFE. They then started allowing you to use the ERS mode to select 2nd prime as an upshift gear and the marketing guys ran the idea and started calling it a 6 speed. Technically, yes it is, but not really...

1. Ignore the numbers on the dash. They don't accurately represent what gear you are in. You'll hit the same final gear either way. I've listed the ratios and the corresponding "Gears" below in both normal and ERS/Tow/Haul mode.

2. Same as above.

3. I don't agree with calling the old trans a 6 speed. As a die-hard Mopar guy, this kind of irritates me. I have the 66RFE (not 65RFE) in my 2012 2500 Hemi Ram and like it a lot. It has 6 normal gears that are properly spaced out. They should have put this trans into the 1500 Rams and Jeeps rather than trying to squeeze a couple more years out of an almost 15 year old transmission. I feel bad for those that were sold on a new Jeep or Ram because it had a "new" 6 speed transmission.

4. Because this mode has zero value and is pointless.

Normal Drive mode:
1=1st – 3.00:1
2=2nd – 1.67:1
3=3rd – 1.00:1
4=4th – 0.75:1
5=5th – 0.67:1

ERS or Tow/Haul mode:
1=1st – 3.00:1
2=2nd – 1.67:1
3=2nd Prime – 1.50:1
4=3rd – 1.00:1
5=4th – 0.75:1
6=5th – 0.67:1

Short answer, just drive it in normal drive mode and don't worry about the mysterious "6th" gear.

 

[mikoz]

Re: how to make the "6 speed" transmission in 2012 Hemi actually work as a 6 speed?

It's all Marketing. Plain and simple.

Shifting from 2nd (1.67) to 2nd Prime (1.50) is pointless. When the 45RFE was designed (As a 4 speed), 2nd prime was intended as a kick down gear only and was never intended to be used as a normal upshift gear. Through some clever programming, they gained a 5th gear when they put it behind the Hemi trucks in 03 and renamed it to a 545RFE. They then started allowing you to use the ERS mode to select 2nd prime as an upshift gear and the marketing guys ran the idea and started calling it a 6 speed. Technically, yes it is, but not really...

1. Ignore the numbers on the dash. They don't accurately represent what gear you are in. You'll hit the same final gear either way. I've listed the ratios and the corresponding "Gears" below in both normal and ERS/Tow/Haul mode.

2. Same as above.

3. I don't agree with calling the old trans a 6 speed. As a die-hard Mopar guy, this kind of irritates me. I have the 66RFE (not 65RFE) in my 2012 2500 Hemi Ram and like it a lot. It has 6 normal gears that are properly spaced out. They should have put this trans into the 1500 Rams and Jeeps rather than trying to squeeze a couple more years out of an almost 15 year old transmission. I feel bad for those that were sold on a new Jeep or Ram because it had a "new" 6 speed transmission.

4. Because this mode has zero value and is pointless.

Normal Drive mode:
1=1st – 3.00:1
2=2nd – 1.67:1
3=3rd – 1.00:1
4=4th – 0.75:1
5=5th – 0.67:1

ERS or Tow/Haul mode:
1=1st – 3.00:1
2=2nd – 1.67:1
3=2nd Prime – 1.50:1
4=3rd – 1.00:1
5=4th – 0.75:1
6=5th – 0.67:1

Short answer, just drive it in normal drive mode and don't worry about the mysterious "6th" gear.

Thanks for the reply. I really am somewhat ticked by this, it's somewhat my own fault for not researching it in advance but I got the whole song and dance at the dealership about how the 6-speed in the 2012 was all new and different (compared to the 2011) and I didn't think to ask "uhh, does it really have 6 usable well spaced gears?". I probably would have been told "yes" anyway, had I asked.

I guess the 8-speed in the 2014 will be a quantum leap forward and explains why the MPG didn't change from 2011->2012 but does change in 2014.

 

[ColdCase]

Re: how to make the "6 speed" transmission in 2012 Hemi actually work as a 6 speed?

The shorter answer is that the V8 transmission has never provided the driver with the capability to select a specific gear, its not controllable or marketed as such.

The driver has some input as the max gear, but otherwise the transmission does whatever its wants. But if you approach redline its probably going to shift anyway. Its a well known feature/operation with this transmission, folks have been discussing it since the 1999 introduction. A little bit of research would have cleared it up... allpar.com has some decent write ups. There are other sites with more info. The control system has many advantages and doesn't lend itself to driver interference. A driver could easily cause an overload... and the computer needs to protect itself from those abusive drivers.

I routinely set mine to 4 around town, 5 on the highway when in traffic, and D out on the open road.

 

[myoung84]

Re: how to make the "6 speed" transmission in 2012 Hemi actually work as a 6 speed?

Thanks for the reply. I really am somewhat ticked by this, it's somewhat my own fault for not researching it in advance but I got the whole song and dance at the dealership about how the 6-speed in the 2012 was all new and different (compared to the 2011) and I didn't think to ask "uhh, does it really have 6 usable well spaced gears?". I probably would have been told "yes" anyway, had I asked.

I guess the 8-speed in the 2014 will be a quantum leap forward and explains why the MPG didn't change from 2011->2012 but does change in 2014.

You salesman telling you that it's an all new transmission doesn't surprise me at all. I doubt he even knows the difference but if he did it wouldn't have mattered. There are some good car salesmen out there, but most of them will tell you whatever you want to hear to get you to leave in a new vehicle.

I don't have a lot of drive time in a Jeep with the 5 speed, just took a 5 minute test drive in a 2013 Hemi when we started considering a new vehicle. I have however had two 545RFE transmissions in two Rams, one 4.7L (04) and one Hemi (2010) with a combined 100k miles of service over about 4 years. They could be better, mainly the ratios, but they aren't terrible transmissions. The are however really starting to show their 15 years of age... The 8 speed is a welcomed upgrade...

 

[mikoz]

Re: how to make the "6 speed" transmission in 2012 Hemi actually work as a 6 speed?

The shorter answer is that the V8 transmission has never provided the driver with the capability to select a specific gear, its not controllable or marketed as such.

The driver has some input as the max gear, but otherwise the transmission does whatever its wants. But if you approach redline its probably going to shift anyway. Its a well known feature/operation with this transmission, folks have been discussing it since the 1999 introduction. A little bit of research would have cleared it up... allpar.com has some decent write ups. There are other sites with more info. The control system has many advantages and doesn't lend itself to driver interference. A driver could easily cause an overload... and the computer needs to protect itself from those abusive drivers.

I routinely set mine to 4 around town, 5 on the highway when in traffic, and D out on the open road.

Sure, it's an automatic and you're just limiting the transmission to certain gears when you change the mode from, say, 4 to 5 or 6 or D or whatever. Some systems like the ZF found in many cars allows direct gear changing, to contrast the capabilities. However, when someone advertises a "6 speed transmission" it should mean that 6 speeds are selectable by the transmission under normal conditions. That clearly is not the case here, if you want to access all 6 gears (which now seems of little merit given the spacing between 2nd and 3rd anyway), you'd have to actually change the mode yourself and most likely the transmission would chose all 6 gears effectively. That's not what most people would assume is meant by a "6 speed" transmission. It's very deceptive advertising. Actually, it's just wrong.

 

[mikoz]

Re: how to make the "6 speed" transmission in 2012 Hemi actually work as a 6 speed?

You salesman telling you that it's an all new transmission doesn't surprise me at all. I doubt he even knows the difference but if he did it wouldn't have mattered. There are some good car salesmen out there, but most of them will tell you whatever you want to hear to get you to leave in a new vehicle.

I don't have a lot of drive time in a Jeep with the 5 speed, just took a 5 minute test drive in a 2013 Hemi when we started considering a new vehicle. I have however had two 545RFE transmissions in two Rams, one 4.7L (04) and one Hemi (2010) with a combined 100k miles of service over about 4 years. They could be better, mainly the ratios, but they aren't terrible transmissions. The are however really starting to show their 15 years of age... The 8 speed is a welcomed upgrade...

There are some things I really like about the car, but, stuff like this really ticks me off. We should have waited for the '14 with the revised everything.

 

[BobsWK2]

Re: how to make the "6 speed" transmission in 2012 Hemi actually work as a 6 speed?

I guess the 8-speed in the 2014 will be a quantum leap forward and explains why the MPG didn't change from 2011->2012 but does change in 2014.

I had a 2012 Overland 4X4 V8 and it was rated 13/20. My 2014 Summit 4X4 V8 is 14/20. Certainly not much improvement but drivability is greatly improved with the ZF built 8 speed compared to the 5/6 speed.

 

[mikoz]

Re: how to make the "6 speed" transmission in 2012 Hemi actually work as a 6 speed?

I had a 2012 Overland 4X4 V8 and it was rated 13/20. My 2014 Summit 4X4 V8 is 14/20. Certainly not much improvement but drivability is greatly improved with the ZF built 8 speed compared to the 5/6 speed.

According to every source I've seen, the 2wd HWY MPG improves by 2MPG with the 8-speed in the 2014 with every else being the same. The 4x4 improves 1MPG in the city.


Gas Mileage of 2012 Jeep Grand Cherokee

Gas Mileage of 2014 Jeep Grand Cherokee