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Tester also differentiates the 9 speed in the MDX from the TLX.
I have both TLX and MDX with 9AT's and I have been on the TLX forum since last December. Compared to TLX, MDX is definitely smoother.

Some examples of TLX behavior with the 9AT :

-Most will have a shift lag between 2nd and 3rd, mine is minor but always present.

-Downshifting across the doglegs in the transmission usually produces a feeling of coasting without engine braking. For example, 6th to 5th to 4th to 3rd. At about 40-45 mph, shifting to 5th produces no engine braking and it seems to just coast. There is a neat trick I use on the TLX but haven't tried on the MDX yet - In the 9HP in TLX and possibly MDX as well, you can skip gears. Same example, 40-45 mph in 6th gear in TLX, triple tap down to 3rd and the engine compression braking feels more instantaneous and places the revs at about 4500 rpm just below the i-VTEC threshold. This is really neat if you are coming into a corner in the SH-AWD and want to power through the curve. Gearing might be a little different in MDX so would engine rpm if you try it. This gear skip feature happens to work in most of ZF's transmissions in cars, buses, etc.

-Driving in the Sport+ mode often can create a temporary late downshift to 1st after the car has stopped which is like a lurch or bump. In my case, driving in the Sport (not Sport +) mode for a few weeks brought it back to normal.

-Sometimes selects too high of a gear too early on low speed right turns - no idea why only right turns, but it happens.

-There are teaching procedures e.g. driving in certain gears at constant speed on level road that do have some effect on both ZF 9HP that Acura uses and the 9AT's that Chrysler makes under license from ZF. However, it is really difficult to produce improvement unless the roads are perfect due to torque deflection also affecting shift quality.

MDX on the other hand, is interesting because the maker chose the shift quality over fuel economy. This is the main reason MDX is smoother than TLX. The 9HP transmission is lighter and has more gears - both would tend to improve fuel economy but the software emphasizes smoothness instead.

In addition to feeling smoother, the implementation of the sport mode is better because you can really feel the engine compression when you decelerate. Many drivers didn't like the coasting feeling described above in the TLX so I definitely think that was reflected into MDX as an improvement.

I think it is possible to introduce shift quality issues in the MDX with the 9HP. It also seems that varied driving styles tend to produce the best results. The transmission is always learning the habits of the drivers and it also compensates for wear. Always drive it with gentle acceleration and that will be reflected, always drive it hard likewise. Variation in driving styles seems to be the key.

There is a lot of info on the TLX forum including some info from ZF about how the 9HP performs.
 

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I am currently in a 16 MDX loaner. 1800 miles and built 6/15. Already drove it a good 50 miles of both highway and stop/go traffic. Here are my thoughts on the tranny.

From a 0-60, the truck feels faster than my 6 speed models. Transmission is busy, shifting, but it is smooth. It feels more like a manual, because the transmission holds the gears a little longer. No doubt, a more sportier feel. Improvement. I like it! In stop and go traffic, it is jerky. Seems confused and doesn't know what to do. A negative. So, basically, if you take your foot off the gas during acceleration, it derails it's wanting to keep going. Then, it fumbles as it figures what to do next.

Stop and go over speed bumps, transmission thumps and hesitates a bit.

When coming to a rolling stop, I can feel the downshifts and sometimes there are thumps. Don't like that.

I can get used to the push button selector, but I do miss my shifter.

Overall, if Acura can smooth it out, I would enjoy driving it more. But, for now, I will stick to my 6 speeds...as I will take a little less "get up and go" for smooth up and down shifts. Just my two cents.
 

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From a 0-60, the truck feels faster than my 6 speed models. Transmission is busy, shifting, but it is smooth. It feels more like a manual, because the transmission holds the gears a little longer. No doubt, a more sportier feel. Improvement. I like it! In stop and go traffic, it is jerky. Seems confused and doesn't know what to do. A negative. So, basically, if you take your foot off the gas during acceleration, it derails it's wanting to keep going. Then, it fumbles as it figures what to do next.


What IDS mode were you in? You said it shifted a lot like a manual transmission and holds onto the gears a little longer but I was wondering if the gear change would be different based on what IDS mode you were in. I know on the 6 speed transmission it makes a big difference depending on the IDS mode.
 

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From a 0-60, the truck feels faster than my 6 speed models. Transmission is busy, shifting, but it is smooth. It feels more like a manual, because the transmission holds the gears a little longer. No doubt, a more sportier feel. Improvement. I like it! In stop and go traffic, it is jerky. Seems confused and doesn't know what to do. A negative. So, basically, if you take your foot off the gas during acceleration, it derails it's wanting to keep going. Then, it fumbles as it figures what to do next.


What IDS mode were you in? You said it shifted a lot like a manual transmission and holds onto the gears a little longer but I was wondering if the gear change would be different based on what IDS mode you were in. I know on the 6 speed transmission it makes a big difference depending on the IDS mode.
IDS was sport. Transmission selector was in "D". I can play around with it on my drive home from work, I still have the loaner.
 

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That's the combination in my setting and I don't notice any of the hesitation in down gearing or rolling stop. Your statement of "holding gear" longer sounds like you were actually in a "S" instead of "D" though.

However, I do notice a side effect on mine. Sometimes when I downshift using the paddle shift while on "D" , I could see the gear changed (rpm goes higher) but not the indicator though - the indicator still shows "D" instead of the gear number. Anybody experienced that?? Is that something normal? It only happens occasionally though. Any input would be helpful :29:


IDS was sport. Transmission selector was in "D". I can play around with it on my drive home from work, I still have the loaner.
 

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Drove it home from work with the IDS in normal. It was better. But when driving in stop and go traffic in a major East Coast City for 40 minutes.....it is not as smooth as my 6 speed MDX. It is jerky. Highway cruising and smooth starts from a stop with steady gas applied....it is great. Also as I said, I do like the pickup from a stop. Sportier than mine.
 

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Interesting observations, as I actually found the 6 sp to come off the line with more punch than the 9. I've noticed though that if I put my lead foot down, the 9 does indeed take off quickly. A slow standard roll off is met with plenty of hesitation though. It's almost like I should just start in 2nd.
 

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Interesting observations, as I actually found the 6 sp to come off the line with more punch than the 9. I've noticed though that if I put my lead foot down, the 9 does indeed take off quickly. A slow standard roll off is met with plenty of hesitation though. It's almost like I should just start in 2nd.
Agreed. It would do fine starting in 2nd.
 
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