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Discussion Starter #1
The Chrysler 62TE has been around for about 6 years now. The "bugs" were pretty much gone by year 2 or 3.

The 62TE is actually based on an older design for a 4 speed, but has significantly improved differential strength, and is known to be quite durable and decently longevity. Second, it's not bad, price-wise, to repair, with great aftermarket support.

The 62TE has been, for quite a few years, THE transmission for the minivans and several cars. And the Dodge Grand Caravan actually weighs in about 300 to 500 lbs less than your basic PM. The PM version has some increased cooling capacity and some (no details given) upgrades, including more cooling capacity.

The Pentastar has won a Ward's 10 best motors designation since it came out, and is known to be pretty durable. Not designed as a mere car motor, it was built for truck durability standards from the beginning. Though early on there were some casting issues from one specific production plant, it has been a very good and efficient motor.

As to the speed it runs at on the highway, that's not a problem at all. The motor's highest efficiency is known to be 1800 to 2500 rpm, meaning there's little or nothing to be gained with taller gears. It is unlikely that there's going to be any serious durability issues with the drivetrain - motor or trans. And, even if you did have to have a trans rebuild at 200 to 300K miles, it can be rebuilt for 1/3 the cost of a sprinter trans, and it can be done at almost any transmission shop.
 

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....cut.....

The motor's highest efficiency is known to be 1800 to 2500 rpm, meaning there's little or nothing to be gained with taller gears.

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It's not quite as simple as stating an RPM range because engine efficiency also depends on engine load. Engineers know this and control transmission gear selection to provide best results for any given required power level.

In many ways engine partial load is more important than engine speed if viewed as an individual parameter. In any case I agree that letting the transmission shift to 5th gear to climb a grade at 3000 RPM or so shouldn't be an issue. After all, the engine doesn't develop maximum torque until it gets up around 4,000 RPM, and can spin to 6,000 if needed without approaching redline.

I honestly don't get why a downshift has become an issue to some. Not when weighed against other options which would reduce fuel economy far more.
 

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I don't get the downshift issue either unless one is thinking that the gas motor is going to have the same torque range as a diesel would at the same rpm.
It's a known fact that an gas engine nowadays, doesn't necessarily use any more gas at a somewhat higher rpm with a lesser throttle opening than a lower rpm at a bigger throttle opening. Now I'm talking here about a modern CAD/Cam designed engine, that's fuel injected and computer controlled, not carbureted or the earlier generations of fuel injection.
 

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My past experiences with trucks and trailing towing makes this all sound spooky.

For example, when towing a light trailing down I-95 for 14 hours, my truck transmission was gear hunting at every grade, or gust of wind. The consequences were an over heated transmission blowing fluid into the engine compartment (out the dipstick tube). This was years ago. BTW, Chevy's engineering solution was to issue self sealing dipstick caps. Things were shoddy years ago.

Today, my truck has way more power and better towing settings in the transmission.

But this still makes me flinch whenever i hear someone say the transmission is changing gears way too much just cruising along loaded on the highway.

That screams under powered to me.
 

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Underpowered is one way to state this condition; but I’d personally call it over-geared. And it’s by design. It’s not that the engine doesn’t have plenty of available power, it’s just that engineers chose a very tall gear in order to maximize fuel economy when the van is traveling on level roads or traveling down hills; which is more often than up hills. Without a doubt they knew the transmission would have to shift down when an 8,000 pound (more or less) van encountered a hill in 6th gear. And that’s the future of higher MPG vehicles so we might as well get used to it. My Honda minivan only has a 5-speed auto but is geared quite high in top gear too. When cruising at 70 to 75 MPH there are a couple of hills I often encounter that force a downshift to 4th gear.

If we consider the engineering concept behind the benefits of a 9-speed transmission (or 7 and 8 for that matter) it will make downshifts even more common. The new ZF 9-speed claims about a 10 percent MPG improvement based on having a wider total gear range. That means that top gear (9th) will be taller still so the engine can run slower and get better fuel economy. But that also means the engine won’t have enough torque at very low RPMs to climb hills; particularly when pulling such a tall gear. I will bet that even multiple downshifts will be common. And also that it’s completely expected by drivetrain engineers.

So, if we don’t like these ProMaster-type frequent downshifts, what are the options? First and easiest is to lower final gearing so that 6th gear is equivalent to present 5th gear (or closer to it). That way the engine will run at higher RPM all the time and not need to downshift as often. Downside of course is that MPG will be lower all the time. Just like in older vans. And who wants that?

A second choice is to leave tall gearing as at present but increase engine displacement to provide more torque. That too would reduce downshifts but would also reduce MPG during normal cruising on level roads. Another option is to add a turbo that can increase torque when necessary to climb hills but doesn’t decrease level-road-cruising MPG significantly. This however adds cost and complexity. Again it’s a tradeoff. And then there is also a bigger engine with displacement-on-demand. They can use bigger engines and drop cylinders when not needed. Again, it adds cost and complexity. This has to be weighed against letting the transmission shift down occasionally, which appears to be the choice PM engineers went with.

The bottom line is that as long as we want to get better MPGs from a naturally-aspirated simpler and lower-cost gasoline engine, we have to size it relatively small and run it at fairly low RPMs so that the engine is loaded down close to its maximum available torque. It’s part of gasoline internal-combustion-engine thermodynamics that can’t be completely overcome. And that’s going to lead to more shifts, which is one reason modern transmissions have more and more gears.


For what it’s worth, my Ford E-350 with a 6.8 liter V-10 rarely downshifts out of top gear. Not even on same hills my Honda minivan does. I personally don’t see that as a badge of honor because it leads to poor fuel economy. So I’d gladly take a smaller engine and more transmission gears if I could swap them.
 

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Underpowered is one way to state this condition; but I’d personally call it over-geared. And it’s by design. It’s not that the engine doesn’t have plenty of available power, it’s just that engineers chose a very tall gear in order to maximize fuel economy when the van is traveling on level roads or traveling down hills; which is more often than up hills. Without a doubt they knew the transmission would have to shift down when an 8,000 pound (more or less) van encountered a hill in 6th gear. And that’s the future of higher MPG vehicles so we might as well get used to it. My Honda minivan only has a 5-speed auto but is geared quite high in top gear too. When cruising at 70 to 75 MPH there are a couple of hills I often encounter that force a downshift to 4th gear.

If we consider the engineering concept behind the benefits of a 9-speed transmission (or 7 and 8 for that matter) it will make downshifts even more common. The new ZF 9-speed claims about a 10 percent MPG improvement based on having a wider total gear range. That means that top gear (9th) will be taller still so the engine can run slower and get better fuel economy. But that also means the engine won’t have enough torque at very low RPMs to climb hills; particularly when pulling such a tall gear. I will bet that even multiple downshifts will be common. And also that it’s completely expected by drivetrain engineers.

So, if we don’t like these ProMaster-type frequent downshifts, what are the options? First and easiest is to lower final gearing so that 6th gear is equivalent to present 5th gear (or closer to it). That way the engine will run at higher RPM all the time and not need to downshift as often. Downside of course is that MPG will be lower all the time. Just like in older vans. And who wants that?

A second choice is to leave tall gearing as at present but increase engine displacement to provide more torque. That too would reduce downshifts but would also reduce MPG during normal cruising on level roads. Another option is to add a turbo that can increase torque when necessary to climb hills but doesn’t decrease level-road-cruising MPG significantly. This however adds cost and complexity. Again it’s a tradeoff. And then there is also a bigger engine with displacement-on-demand. They can use bigger engines and drop cylinders when not needed. Again, it adds cost and complexity. This has to be weighed against letting the transmission shift down occasionally, which appears to be the choice PM engineers went with.

The bottom line is that as long as we want to get better MPGs from a naturally-aspirated simpler and lower-cost gasoline engine, we have to size it relatively small and run it at fairly low RPMs so that the engine is loaded down close to its maximum available torque. It’s part of gasoline internal-combustion-engine thermodynamics that can’t be completely overcome. And that’s going to lead to more shifts, which is one reason modern transmissions have more and more gears.


For what it’s worth, my Ford E-350 with a 6.8 liter V-10 rarely downshifts out of top gear. Not even on same hills my Honda minivan does. I personally don’t see that as a badge of honor because it leads to poor fuel economy. So I’d gladly take a smaller engine and more transmission gears if I could swap them.
What Chance says is how things are now and will be in the future. More gears mean more downshifts going up small hills. And like he says, the immediate solution is to run in a lower gear, which will help with the heat thing, or larger thirstier motors.
What I would do if I was in a hilly or mountainous area, is to run the 6spd in 5th, and/or the so called tow/haul mode all the time. It won't hurt anything except for a small decrease in mileage, but it sure helps with that shift all the time situation, and the transmission heat buildup
 

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Discussion Starter #7
Just to be clear, transmission heating is not from shifting (that doesn't create much heat), but from the converter being unlocked. As far as I know, pentastar / 62TE combination spends its time locked 6, 5, and 4, and being unlocked most of the time in the bottom 3.

But, the heat comes, not so much from being unlocked, but being unlocked while there's a huge rpm difference between input and output of the converter.

And, as has been said... the need for higher rpm's is all about small displacement. It HAS to have the mechanical leverage of a high numerical ratio to do what you ask it to.
 

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Discussion Starter #8
It's not quite as simple as stating an RPM range because engine efficiency also depends on engine load. Engineers know this and control transmission gear selection to provide best results for any given required power level.
Sadly, they're pretty much not chosen for their great economy. There's generally huge compromises built in, often to make it feel more responsive.

If the programming lets you lock it in any particular gear manually, it's an option. I get 3-4 mpg better in my wife's Dart than she does, simply because I pay attention to using the motor and transmission that way.
 

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Ok guys, I keep seeing this posted on forums all the time, and it really annoys me because it is just not true. More gear selection does not mean more downshifting and up shifting while on the road. I have first hand experience with the 8 speed and that is NOT the case.
 

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Ok guys, I keep seeing this posted on forums all the time, and it really annoys me because it is just not true. More gear selection does not mean more downshifting and up shifting while on the road. I have first hand experience with the 8 speed and that is NOT the case.
Correct. Tall overdrives are the culprit.
 

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Just to be clear, transmission heating is not from shifting (that doesn't create much heat), but from the converter being unlocked. As far as I know, pentastar / 62TE combination spends its time locked 6, 5, and 4, and being unlocked most of the time in the bottom 3.

But, the heat comes, not so much from being unlocked, but being unlocked while there's a huge rpm difference between input and output of the converter.

And, as has been said... the need for higher rpm's is all about small displacement. It HAS to have the mechanical leverage of a high numerical ratio to do what you ask it to.
This is correct, the unlocked converter is the heat builder, not the overdrive gears and/or the shifting
 

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Ok guys, I keep seeing this posted on forums all the time, and it really annoys me because it is just not true. More gear selection does not mean more downshifting and up shifting while on the road. I have first hand experience with the 8 speed and that is NOT the case.
With all due respect you are probably taking the words out of context.

You are correct that having more gears in itself doesn't cause more downshifts because the engine runs out of available torque. As long as the highest gear is the same it doesn't matter how many gears the transmission has -- whether 4, 6 or 8 speeds, etc....

But the reason auto manufacturers are going to greater number of transmission gears is so they can extend (or increase) the transmission's total gear range. This allows them to run a smaller engine with less torque because 1st gear can be much lower which then allows the smaller engine to start moving the vehicle on an incline, and at the other end of the transmission range it will allow very tall gearing to save fuel.

Not that long ago an automatic transmission had 3 speeds with a gear range of about 2.5 to 1 overall. That normally meant running at around 3000 RPM at highway speeds. With that amount of gearing in highest gear there was little need for large V8 engines to ever need a downshift on hills.

Then an overdrive was added to make a 4 speed auto and engine RPM at highway speeds dropped to around 2000 RPM (more or less for typical American family sedan). Because of the lower engine RPM and less torque multiplication due to higher gearing, the probability of having to downshift increased.

Now we have up to 9 speed automatics with a total gear range approaching 10 to 1. And not only do many vehicles have smaller engines, but also instead of running 20 to 25 MPH per 1000 RPM in highest gear, they run close to 40 MPH per 1000 RPM. On some cars engines are running well under 2000 RPM at 70 MPH.

Obviously there are exceptions (like performance applications), but the trend towards more transmission gears has been driven by auto manufacturers pursuing smaller engines and or taller final gearing in order to improve fuel economy.

And the combination of smaller engines and taller top gears will indeed force more downshifts than in the past. It's just the physics of it. The "cause-and-effect" implied in the wording is sometimes not completely clear. Particularly in forums where writing tends to be too brief.

Like I stated, the extra gears themselves don't force more downshifts. It's what causes manufacturers to go to more transmission gears in the first place that leads to greater need for downshifts (i.e. -- smaller engine combined with taller gearing like on the PM).
 

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The pentastar with the 8 speed does not constantly downshift and up shift once you've gained your desired speed. I have the combo in a truck, which is the closest example we have. And it does improve economy
 

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The pentastar with the 8 speed does not constantly downshift and up shift once you've gained your desired speed. I have the combo in a truck, which is the closest example we have. And it does improve economy

No disrespect here, but I don't believe that. We have a 2012 Jeep Wrangler with the NAG-1 5 spd. and the 3.6 Pentastar. This vehicle downshifts & upshifts all the time with virtually any change in road conditions when we're below say, 65 mph.
You have a heavier vehicle with 3 more gears to choose from......just sayin
 

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The pentastar with the 8 speed does not constantly downshift and up shift once you've gained your desired speed. I have the combo in a truck, which is the closest example we have. And it does improve economy
Ewelectric, I don't think anyone is reporting this issue as "CONSTANTLY" downshifting. Based on what I've read in this forum I see the issue as it happening more often than drivers are used to; likely compared to previous vans that had much larger engines. Guys that are switching from Fords and Chevys probably had V8 engines with much larger displacement than 3.6 liters. And those switching from Sprinters almost certainly had a turbo diesel. Very few Sprinters with V6 gasoline engines were sold before they were taken off market. It seems to me that we are comparing apples and oranges when it comes to drivetrain expectations.

Regarding your truck, you haven't stated the final gearing to compare to a ProMaster. They should be similar but maybe not. Also, your pickup truck may not be loaded to the same weight as some of these PMs that carry selves full of parts and equipment.

And finally, let's don't forget that a high-roof ProMaster is around 20 inches taller and also slightly wider than many pickups, so the cross section to the wind is much larger. At highway speeds it must use more engine power than your truck which leaves less in reserve to climb a hill. It really shouldn't be that surprising that occassionally they have to downshift at 70 MPH when the highway turns up in elevation.

And it's also very possible that climbing some of these grades in 5th may actually be more fuel efficient than in 6th, so it may be a matter of programing for better fuel economy. Even if the engine could pull a hill in 6th, it may be advantageous to drop down a gear to 5th.
 

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I was just reading Motor Trends test of the RAM 1500 diesel.

They said this

"That's the brilliance of this truck: It never feels like it's trying. The gas-powered trucks spend more time hunting for gears and revving at engine speeds the diesel will never see. Both the shifting and NVH from high-rpm operation add to driver fatigue during long trips -- especially when towing or hauling. The engine noise and vibration in the EcoDiesel are isolated, reduced to a mechanical hum at cruising. This, combined with the other amenities, means the miles just melt by."

Their comments, and Ram pricing the Diesel option at $2850, certainly makes me want to wait.
 

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Oh yeah, all the reviews and articles I've read of the EcoDiesel Ram have been gushing in praise at how the drivetrain operates & pulls compared to the gas.....
 

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I was just reading Motor Trends test of the RAM 1500 diesel.

They said this

"That's the brilliance of this truck: It never feels like it's trying. The gas-powered trucks spend more time hunting for gears and revving at engine speeds the diesel will never see. Both the shifting and NVH from high-rpm operation add to driver fatigue during long trips -- especially when towing or hauling. The engine noise and vibration in the EcoDiesel are isolated, reduced to a mechanical hum at cruising. This, combined with the other amenities, means the miles just melt by."

Their comments, and Ram pricing the Diesel option at $2850, certainly makes me want to wait.
Isn't it hard to extrapolate feedback to ProMaster when engines and vehicles are so different?

Both engines burn same diesel, but one is I4 and other is V6. PM has 295 lb-ft and pickup 420 lb-ft. Pickup is RWD body on frame and automatic, and PM is FWD with unitized construction and manual transmission. It's very possible, very likely in my opinion, that driving and NVH will be very different between PMs and RAM pickups.

Not trying to put down diesel PM, just stating these are very different vehicles on which to extrapolate "diesel" feedback.
 

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wouldnt more gears mean that during acceleration it passes through more gears? same with deceleration.
Correct, as long as transmission total gear range is similar. More gears does mean more shifts, but everything else being equal, it also means each step will be smaller. That's normally seen as a benefit to improve performance and smoothness.

I suppose it can be overdone though. Which may explain why the CVT transmission is becoming more common. Maybe drivers really dislike "shifts" and gear hunting more than I thought.
 
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