7 & 8 speed transmissions

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Originally Posted By: dave1251
Originally Posted By: grampi
Originally Posted By: 440Magnum
Originally Posted By: Number_35
I think that beyond a certain point the complexity outweighs the gains. I'd say that 5 or 6 forward speeds is the sweet spot.



Drive a ZF-8 Challenger or Grand Cherokee back-to-back with a NAG-1 5-speed version, and you'll drop that line of thinking REAL quick. Or use a GM 5-speed vs 8-speed for your comparison, doesn't matter. The advantage of more forward gears is especially obvious with a normally-aspirated v6, the V8s and turbo engines can somewhat overcome the wide gaps of a 5-speed, but the v6 really came into its own when it got paired with the 8-speed.



If you constantly drive wide open throttle, the 8+ speeds are nice. Any other time they're just annoying. They're constantly up and down shifting, and they always have the engine lugging. Even the slightest bit of acceleration requires a down shift. I know why they're going with these mega-gear trannies and it's because they keep going with smaller and smaller displacement engines that have no torque, so they have a hard time pulling the wider ratio gaps between the gears. Larger displacement engines don't need that many gears...


Simply not true. Have fun with you 3 on the tree. The rest of us like progress.


Have fun taking out a 2nd mortgage to have your 8 speed rebuilt...
 
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Who doesn't enjoy the feeling of non-stop shifting? If the tranny isn't passing through at least 7 ratios and torque reduction events between 0-45MPH, you're not really living!
 
Originally Posted By: edwardh1
why now- selling 5 6 7 8 etc speed auto transmissions? has there been some technology breakthrough??

Welcome to 21st century. Where have you been man?
 
I can't speak for a 7 or 8 speed autobox but without question my wife's Camry is more driveable around town when I select S4 sequential mode locking out both the overdrive gears. When in normal drive mode the throttle response is mushy at ~60 kph and will kick down to a lower gear abruptly for any reasonable increase in speed. With S4 I can modulate my speed more smoothly with better response whether on or off the throttle. This is important to me in maintaining proper gap control (distance & stagger) in a world where most drivers are oblivious to same.

Not sure if more gears solves this problem but I'm sure fuel economy is a major factor in the decision making.
 
There are times when I wish there were a couple more gears in the Tundra and Silverado. Tundra has a lower rear end ratio which makes it excellent for acceleration but still revs above 2000RPM when driving on the freeway. The Silverado is geared a bit taller for excellent highway cruising but acceleration and passing power is not really excellent.
 
Originally Posted By: AZjeff
Wouldn't putting 10 speeds in a space that had 6 speeds mean smaller, thinner and weaker parts?


Nope, the packaging expertise is amazing. These slushboxes are not always bigger, and weaker you say? How about a Bentley with AWD and 600 foot pounds of torque? Jag supercharged V-8? Or my weak 395 hp Hemi with 410 foot pounds? At least ZF 8 speeds have no problem with durability.

The real issue is programming. That's the reason some of us have enjoyed a smooth and quiet ride with some multi-speed transmissions while others have had clunky, surging, experiences. Many mfgrs have simply not mastered the complexity of writing elaborate shift schedules and throttle matching/torque management programs for these new slushboxes. As more figure it out they will get even better!
 
Originally Posted By: 440Magnum
Originally Posted By: Number_35
I think that beyond a certain point the complexity outweighs the gains. I'd say that 5 or 6 forward speeds is the sweet spot.



Drive a ZF-8 Challenger or Grand Cherokee back-to-back with a NAG-1 5-speed version, and you'll drop that line of thinking REAL quick. Or use a GM 5-speed vs 8-speed for your comparison, doesn't matter. The advantage of more forward gears is especially obvious with a normally-aspirated v6, the V8s and turbo engines can somewhat overcome the wide gaps of a 5-speed, but the v6 really came into its own when it got paired with the 8-speed.

Our city police use mostly 3.6l Chargers, the police package only comes with the 5 speed. The civilian cars with the 8 speed pull much harder and are more fun to drive.
 
Originally Posted By: SteveSRT8
Originally Posted By: AZjeff
Wouldn't putting 10 speeds in a space that had 6 speeds mean smaller, thinner and weaker parts?


Nope, the packaging expertise is amazing. These slushboxes are not always bigger, and weaker you say? How about a Bentley with AWD and 600 foot pounds of torque? Jag supercharged V-8? Or my weak 395 hp Hemi with 410 foot pounds? At least ZF 8 speeds have no problem with durability.

The real issue is programming. That's the reason some of us have enjoyed a smooth and quiet ride with some multi-speed transmissions while others have had clunky, surging, experiences. Many mfgrs have simply not mastered the complexity of writing elaborate shift schedules and throttle matching/torque management programs for these new slushboxes. As more figure it out they will get even better!


Exactly, the better integrated ones like the HP70 are awesome, great shifting, great 1/4 mile times and gas mileage.

then you have some oems with low tq engines taking the cheap way out with cvt's , drive one of them and tell me what you would rather have? Ill take the 8,9 or 10 spd thank you!
 
Originally Posted By: AVB
Originally Posted By: 440Magnum
Originally Posted By: Number_35
I think that beyond a certain point the complexity outweighs the gains. I'd say that 5 or 6 forward speeds is the sweet spot.



Drive a ZF-8 Challenger or Grand Cherokee back-to-back with a NAG-1 5-speed version, and you'll drop that line of thinking REAL quick. Or use a GM 5-speed vs 8-speed for your comparison, doesn't matter. The advantage of more forward gears is especially obvious with a normally-aspirated v6, the V8s and turbo engines can somewhat overcome the wide gaps of a 5-speed, but the v6 really came into its own when it got paired with the 8-speed.

Our city police use mostly 3.6l Chargers, the police package only comes with the 5 speed. The civilian cars with the 8 speed pull much harder and are more fun to drive.

Why? ZF8 proved much more reliable then 5 speeder in that car. Any other reason for that (cost)?
 
I love the 8 speed auto in my new Corvette, it shifts lightning quick at full throttle and at part throttle it's super smooth. It never hunts for a gear at all, and when I am cruising along at any speed and put my foot down, there is no lag at all, it always shifts down to a point in the powerband where it will pull hard. I remember just a few years ago when I had my 98 Corvette with the 4 speed auto, there were many times where I would go full throttle while moving and it just didn't have enough gears to put it in the sweet spot of the powerband when it downshifted.
 
Just to throw gas on the fire my latest ride has a single speed gear reduction box. don't need gears when the motor makes 440tq from 0-5100rpm(43mph) then plateaus at 416hp till 8600rpm(73mph). and rated at 91mpg despite not using liquid fuel.

BOTH trains of thought that high gear count is being used to mask narrow power bands and make for small efficiency gains are correct, as are those who say this makes for huge complexity and astronomical repair bills if something does fail.

Cars are HEAVY these days with a lot of power and often narrow powerbands. People think old cars were heavy but a 2017 4cylinder Impala is 300lbs heavier than a 1964 impala and a well optioned one with the V6 is another 200lbs heavier. The 1964 Impala wagon is lighter than a well optioned 2017...... Adds up to needing a lot of gears to keep it in the narrow powerband and a hard life for the tranny with all the power and weight.

Patman, despite popular myth the LS motors are a bit late on torque band, the 6speeds really compliment them well where the older smallblocks that made torque sooner were happy with 4. I was very happy with the 4L60E behind my LT1s(gen 2 1990s motors).
 
Originally Posted By: AVB
I think it is mostly because of the column shifter.

But ZF8 has electronic connection between shifter and transmission.
You can literally put shifter anywhere.
 
I think the electronic connection is the problem. I think they wanted to keep the mechanical connection.
 
Originally Posted By: AVB
I think the electronic connection is the problem. I think they wanted to keep the mechanical connection.

Ah well....
 
Originally Posted By: DJ


Patman, despite popular myth the LS motors are a bit late on torque band, the 6speeds really compliment them well where the older smallblocks that made torque sooner were happy with 4. I was very happy with the 4L60E behind my LT1s(gen 2 1990s motors).


I have always felt that the L98 had the most low end of all of the Corvette engines of the past few decades, with the original LT1 coming second behind that. The LS1, LS2, LS3, and even the new LT1, definitely have sacrificed some low end grunt in order to achieve better numbers up top.

But I did have two different LT1 powered F-bodies with the 4L60E and I do feel that there were gaps in the powerband with them as well, if you hit it on a roll at certain speeds it just didn't fall into the sweet spot like it would if it had more gears to choose from. That's because at certain highway speeds if you put your foot to the floor it would only shift down from 4th to 3rd and it still wasn't high enough in the powerband. I came to learn where those "dead spots" were and would actually slow down a little bit first because I knew that below a certain speed that the trans would downshift into 2nd instead. Same with my 98 Corvette too. But with 8 speeds to choose from in my new Corvette, it never has that problem at all, no matter what speed you're going, if you hammer it, it will end up in the right spot of the powerband so that there are no "dead spots"
 
Originally Posted By: Patman
I remember just a few years ago when I had my 98 Corvette with the 4 speed auto, there were many times where I would go full throttle while moving and it just didn't have enough gears to put it in the sweet spot of the powerband when it downshifted.


That's what the M6 was for...
 
Originally Posted By: DJ
Patman, despite popular myth the LS motors are a bit late on torque band, the 6speeds really compliment them well where the older smallblocks that made torque sooner were happy with 4. I was very happy with the 4L60E behind my LT1s(gen 2 1990s motors).


The '01 thru '04 LS1s produced 300 ft lbs at just 1000 RPMs, which is neither late nor mythical...
 
Originally Posted By: grampi
Originally Posted By: DJ
Patman, despite popular myth the LS motors are a bit late on torque band, the 6speeds really compliment them well where the older smallblocks that made torque sooner were happy with 4. I was very happy with the 4L60E behind my LT1s(gen 2 1990s motors).


The '01 thru '04 LS1s produced 300 ft lbs at just 1000 RPMs, which is neither late nor mythical...


Did you ever buy that Corvette you were looking at a few months ago ?
 
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