ib516 bought a new vehicle today

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Nice rig.

Perhaps it would adapt rather well to custom lower final gears if it were used in heavy towing close to the limit. It would certainly have reasonable OD left for economic light cruising.

Wes
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ib516 wrote:
In my limited experience, they go through each gear sequentially. Of course on kickdown, it will drop 3, 4, or 5 gears at a time. I test drove two units, neither was searching for gears at any time. I was surprised at how smooth they were.

The multiple gears allow for good performance. A really deep first makes it feel very zippy off the line, and the higher gears make it able to deal with headwinds and hills efficiently. Think about it-- an old tech 4 speed would have to hunt between 3rd (too low) and 4th (too high), when what it needs is gear 3.5. This has that gear.

If it needs more than four gears, it's either a class 7 truck or needs more engine. :D

wilber1 wrote:

larry barnhart wrote:
Hard for me to understand needing more gears. Our GMC Acadia has 6 speeds, our 98 Buick park avenue had 4 and it was a great set up. Our 5 speed trannie in our chev works great .
chevman

It's hard to understand until you have had them. Automatics have gone from two speeds, to three speeds, to four speeds, to five and six speeds. So far I have never heard anyone say they wanted to go back to a transmission with fewer gears.

I drove a Cruze recently with a 6-speed slushbox...in a word, dreadful. It was constantly shifting up and down unless I was on the highway.

I'm surprised to see the Cherokee has such a big split between first & second gears.

ve7prt wrote:

wilber1 wrote:

larry barnhart wrote:
Hard for me to understand needing more gears. Our GMC Acadia has 6 speeds, our 98 Buick park avenue had 4 and it was a great set up. Our 5 speed trannie in our chev works great .
chevman

It's hard to understand until you have had them. Automatics have gone from two speeds, to three speeds, to four speeds, to five and six speeds. So far I have never heard anyone say they wanted to go back to a transmission with fewer gears.

Personally, I can't see why you need so many flippin' gears for a gas engine? Sorry, but if you get the engine turning too slowly for a given speed, it's gonna lug something fierce. Or the tranny is gonna be constantly shifting to maintain speed up and down hills.

Now, for a diesel engine, I could see having 8/9/10 gears. I know my truck is a 6 speed, and I'd love to see 8, or 10, in it. Maybe one more OD ratio, but certainly a couple more straight ratios.

But, 8 or more gears for a gas engine is getting stupid. Besides, when you go into OD, doesn't the engine have to work harder to maintain speed than if you were at 1:1?

Cheers!
Mike

I have the ZF 8 speed behind a Turbo DI gas engine and it is with out a doubt the nicest transmission I have ever owned. The torque converter is only used in idle, reverse and to launch the vehicle, then it locks until just before you come to a stop. Shifts are super fast and when the converter unlocks it often feels like a manual clutch disengaging as you come to a stop. It doesn't split shift on the way up but it can kick down directly from 8th to 2nd. It is a six speed with 2 OD's and all the six speed autos out there are four speeds with 2 OD's, so you have two more gears than a six speed between 1st and 1:1 and you never feel like you are stuck between a gear too high and a gear too low.

What makes me curious is why MOPAR took an eight speed with two OD ratios and made it a nine speed with four OD ratios. I'm sure they had a reason, I'd just like to know what it was.

In my limited experience, they go through each gear sequentially. Of course on kickdown, it will drop 3, 4, or 5 gears at a time. I test drove two units, neither was searching for gears at any time. I was surprised at how smooth they were.

The multiple gears allow for good performance. A really deep first makes it feel very zippy off the line, and the higher gears make it able to deal with headwinds and hills efficiently. Think about it-- an old tech 4 speed would have to hunt between 3rd (too low) and 4th (too high), when what it needs is gear 3.5. This has that gear.

ve7prt wrote:

wilber1 wrote:

larry barnhart wrote:
Hard for me to understand needing more gears. Our GMC Acadia has 6 speeds, our 98 Buick park avenue had 4 and it was a great set up. Our 5 speed trannie in our chev works great .
chevman

It's hard to understand until you have had them. Automatics have gone from two speeds, to three speeds, to four speeds, to five and six speeds. So far I have never heard anyone say they wanted to go back to a transmission with fewer gears.

Personally, I can't see why you need so many flippin' gears for a gas engine? Sorry, but if you get the engine turning too slowly for a given speed, it's gonna lug something fierce. Or the tranny is gonna be constantly shifting to maintain speed up and down hills.

Now, for a diesel engine, I could see having 8/9/10 gears. I know my truck is a 6 speed, and I'd love to see 8, or 10, in it. Maybe one more OD ratio, but certainly a couple more straight ratios.

But, 8 or more gears for a gas engine is getting stupid. Besides, when you go into OD, doesn't the engine have to work harder to maintain speed than if you were at 1:1?

Cheers!
Mike

I'm no engineer (understatement, LOL) but I've read just the opposite theory, that with their wonderful torque curves diesel engines can get by with less gears due to better ability to stay "in a sweet spot," whereas gasoline engines require more gearing options to keep in their optimal powerband.

The only drawback I see to more gears is more shifting, which logic would dictate means more wear over a given set of miles than less gears.

Having said that, I certainly would think that multiple-speed (8,9,10) speed trans would be programmed to skip-shift when conditions allow, eliminating the "more wear" scenario from excess shifting.

Anyone know if the 8 & 9 speed boxes that recently hit the market (Ram/Jeep/Chrysler for instance) skip shifts or do they roll through each gear?

Ib516?

wilber1 wrote:

larry barnhart wrote:
Hard for me to understand needing more gears. Our GMC Acadia has 6 speeds, our 98 Buick park avenue had 4 and it was a great set up. Our 5 speed trannie in our chev works great .
chevman

It's hard to understand until you have had them. Automatics have gone from two speeds, to three speeds, to four speeds, to five and six speeds. So far I have never heard anyone say they wanted to go back to a transmission with fewer gears.

Personally, I can't see why you need so many flippin' gears for a gas engine? Sorry, but if you get the engine turning too slowly for a given speed, it's gonna lug something fierce. Or the tranny is gonna be constantly shifting to maintain speed up and down hills.

Now, for a diesel engine, I could see having 8/9/10 gears. I know my truck is a 6 speed, and I'd love to see 8, or 10, in it. Maybe one more OD ratio, but certainly a couple more straight ratios.

But, 8 or more gears for a gas engine is getting stupid. Besides, when you go into OD, doesn't the engine have to work harder to maintain speed than if you were at 1:1?

Cheers!
Mike

cvt,ftmfw

larry barnhart wrote:
Hard for me to understand needing more gears. Our GMC Acadia has 6 speeds, our 98 Buick park avenue had 4 and it was a great set up. Our 5 speed trannie in our chev works great .
chevman

It's hard to understand until you have had them. Automatics have gone from two speeds, to three speeds, to four speeds, to five and six speeds. So far I have never heard anyone say they wanted to go back to a transmission with fewer gears.

Hard for me to understand needing more gears. Our GMC Acadia has 6 speeds, our 98 Buick park avenue had 4 and it was a great set up. Our 5 speed trannie in our chev works great .
chevman