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  #1  
Old 06-21-2011, 12:53 PM
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What to expect from the new HEMI 6 spd tranny?

I'm gearing up to order a 2012 Overland. I was set on the V6, due to MPG concerns, however the new tranny in the HEMI is tempting.

Realistically, what improvements should we expect from the 6 speed? 1-2+ MPG? Slightly faster acceleration? Smoother shifting? Any other noticeable improvements?
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Old 06-21-2011, 01:04 PM
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Re: What to expect from the new HEMI 6 spd tranny?

You may see a very slight increase in mpg but nothing to write home about. I would be quite surprised if it's anything more than 1-2 mpg.

FWIW I really like the v6 and with all the current updates I now have no complaints at all about the tranny either.
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Old 06-21-2011, 01:15 PM
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Re: What to expect from the new HEMI 6 spd tranny?

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Originally Posted by SixZeroFour View Post
You may see a very slight increase in mpg but nothing to write home about. I would be quite surprised if it's anything more than 1-2 mpg.

FWIW I really like the v6 and with all the current updates I now have no complaints at all about the tranny either.
What updates are you referring to?
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Old 06-21-2011, 01:33 PM
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Re: What to expect from the new HEMI 6 spd tranny?

Don't mix apples and oranges, the current multi-speed and future 6sp in the Hemi are completely different than the Mercedes trans in the V6.

The "new" 2012 6 sp for the Hemi is a reworked version of the existing "multi-speed" transmission that's the current Hemi trans. It's unlikely there will be any MPG improvements since the current trans already has 2 overdrives. It's been said the primary reason the the redesign and change in designation is for drivetrain performance improvement. The current trans setup with the Hemi is somewhat crude IMHO and needs some work to get close to being as good as the rest of the vehicle is.
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Old 06-21-2011, 02:26 PM
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Re: What to expect from the new HEMI 6 spd tranny?

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Originally Posted by Jeremy1983 View Post
I'm gearing up to order a 2012 Overland. I was set on the V6, due to MPG concerns, however the new tranny in the HEMI is tempting.

Realistically, what improvements should we expect from the 6 speed? 1-2+ MPG? Slightly faster acceleration? Smoother shifting? Any other noticeable improvements?

My guess would be several programming updates. It seems When chrysler makes changes to a transmission or comes out with a new trans it hits the road and then over the next year or two they have program updates to get it shifting smooth. Case in point would be th 2011 WK2 both the tranmissions are very smooth in the 09 and 10 Grand Cherokee and then due to changes they have these tsb's to work out the problems. Just like the new 8 speed that is coming it may be a great transmission but if the programming isn't right it could operate like crap. So I would wait until at least six to eight months in to see what people are saying.
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Old 06-21-2011, 02:56 PM
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Re: What to expect from the new HEMI 6 spd tranny?

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Originally Posted by Jeremy1983 View Post
What updates are you referring to?
There were several updates issued for the trans software for the current 5spd each of which made a noticeable improvement to the way the Jeep performs on the road. At first the 5-speed had strange drive-by-wire response and a few dead spots in the powerband but this has all been fixed with the software updates. Now it drives just like it should (at least mine does!)

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Originally Posted by mjw930 View Post
Don't mix apples and oranges, the current multi-speed and future 6sp in the Hemi are completely different than the Mercedes trans in the V6.
I wasn't mixing apples, oranges or anything else... the op noted he was set on the v6 but was considering the hemi because of the new tranny. I was simply offering my thoughts on the V6.
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Old 06-21-2011, 03:14 PM
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Re: What to expect from the new HEMI 6 spd tranny?

I recognize that this is against the grain, but IME, the current 2011 Hemi and otherwise "dated" transmission are well suited to each other. Performs well for me on and off road, high speed highway, urban driving, at altitude, and when towing upwards of 5k lbs. Love the manual like features, and the ability to disable MDS with one click of the shifter. No shudder, no stalls, nothing but good for me. Highway MPG is decent as well at circa 19-20 mpg range even with elevation gain and altitude here in CO. My only complaint is the drive by wire lag which hopefully can be overcome when the tuners figure out how to crack the code.

That said, someone earlier suggested on another tranny thread that perhaps the existing 545 tranny could perhaps be reprogrammed or flashed to the upcoming 6 speed, we'll see.
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Old 06-21-2011, 03:33 PM
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Re: What to expect from the new HEMI 6 spd tranny?

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Originally Posted by moosehead View Post
I recognize that this is against the grain, but IME, the current 2011 Hemi and otherwise "dated" transmission are well suited to each other. Performs well for me on and off road, high speed highway, urban driving, at altitude, and when towing upwards of 5k lbs. Love the manual like features, and the ability to disable MDS with one click of the shifter. No shudder, no stalls, nothing but good for me. Highway MPG is decent as well at circa 19-20 mpg range even with elevation gain and altitude here in CO. My only complaint is the drive by wire lag which hopefully can be overcome when the tuners figure out how to crack the code.
That does indeed buck the trend. After a test drive, I thought it would be fine but perhaps didn't make the most efficient use of available power. But, if others agree that it's a very well-matched transmission after many more miles, I'm interested to hear!
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Old 06-21-2011, 04:59 PM
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Re: What to expect from the new HEMI 6 spd tranny?

I don't think the package is bad, if it was I wouldn't have purchased it. What I do believe is there are some characteristics that are unique, somewhat crude and better suited for a truck than a high end SUV. This comes from having owned a Porsche Cayenne Turbo, BMW X5 4.8i, VW Touareg V8, and Chevy Trailblazer SS.

The single thing that disappoints me is exactly what is described in this post, uneven drivetrain engagements, surging on the highway, and chugging during coasting. None of the above vehicles exhibit these characteristics.
Quote:
The Service Manager called an engineer in from Chrysler to drive my vehicle. The Service Manager drove a new car off the lot and said it was great. He drove my car and told me he thought the drivetrain was rough to say the least. The Engineer told him that this sensation is the MDS activating and de-activating. When the Eco light is on, the car is in 4 cylinder mode. But the car can be in 4 cylinder mode and the Eco light will not be on. The engineer told him that the inertia change associated with engaging/disengaging large displacement cylinder heads was difficult for them to shield from the driver. They did what they could on this generation but hope to address better on future models, although they do not know how. The engineer said that all of the Hemi engine vehicles have this characteristic and they are getting a lot of complaints about it. He said it is within the design parameters of the vehicle.

My Service Manager asked why the one on their lot drove so great. The engineer told him that the torque converter does not start to break-in its lock-up for 1,000 - 2,000 miles so drivers will not feel the normal characteristics of the car until then. My vehicle operates as designed; all the uneven drivetrain engagements, surging on the highway, and chugging during coasting is normal.
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Old 06-21-2011, 05:19 PM
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Re: What to expect from the new HEMI 6 spd tranny?

Here's some interesting reading:

http://www.allpar.com/mopar/transmissions/545RFE.html (65RFE discussed near the end)

I like those ratios, I think it will be a better driving experience however, I wonder if they continue to have the underdrive for Tow/Haul? They may not need it with the smaller gaps between 1-2 and 2-3.
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Old 06-21-2011, 07:14 PM
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Re: What to expect from the new HEMI 6 spd tranny?

Quote:
Originally Posted by moosehead View Post
I recognize that this is against the grain, but IME, the current 2011 Hemi and otherwise "dated" transmission are well suited to each other. Performs well for me on and off road, high speed highway, urban driving, at altitude, and when towing upwards of 5k lbs. Love the manual like features, and the ability to disable MDS with one click of the shifter. No shudder, no stalls, nothing but good for me. Highway MPG is decent as well at circa 19-20 mpg range even with elevation gain and altitude here in CO. My only complaint is the drive by wire lag which hopefully can be overcome when the tuners figure out how to crack the code.

That said, someone earlier suggested on another tranny thread that perhaps the existing 545 tranny could perhaps be reprogrammed or flashed to the upcoming 6 speed, we'll see.
I can gurantee you and everyone else that a future software update will not magically fabricate new steel gears.
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Old 06-21-2011, 07:17 PM
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Re: What to expect from the new HEMI 6 spd tranny?

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Originally Posted by vikingdave View Post
I can gurantee you and everyone else that a future software update will not magically fabricate new steel gears.
Lol. Rigghhht
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