Hard to read.

In theory I have no issues with 4-speed autos. I think 6-spped autos are the sweet spot though. That's pretty much the max for "single gate" manual transmissions, all the higher ones have to be run thru the gates multiple times.

 

It doesn't matter if it's perception or reality. You have to stay ahead of the game.. If people assume that 5 and 6 speeds are better than 4 then you better start making them..

 

Hard to read.

In theory I have no issues with 4-speed autos. I think 6-spped autos are the sweet spot though. That's pretty much the max for "single gate" manual transmissions, all the higher ones have to be run thru the gates multiple times.

Sorry if my thoughts are a bit scattered in my initial post, I sort of hastily wrote that blurb.
My main concern was to point out that although a 6-speed transmission may not present many scientific advantages over a 4-speed, people still lust after them. People want the 4.3L V6 from the S10 even though the I5 in the Colorado makes more power and is more efficient. And even though the Honda Pilot may seat 8 and get relatively good mileage, can you really compare it to an 8-passenger Suburban?? The automotive industry is very compelling to me as it doesn't only take engineering skill to produce beautiful vehicles, but you have to execute techniques to make your customers think you're producing beautiful vehicles. The 4-speed may actually be technically more advanced than the 6-speed, but the customers will think right away that 6 > 4 implies that the 6-speed is better. It's all just one-upsmanship.

 

it doesnt really matter too much, as long as they have similar final drive gear ratios. 4-5-6 speed.

 

The most noticable thing to the driver would be the larger rev drop-offs with a 4sp rather than a 6sp; and, like you said, this decreases performance. But regardless of the 0-60 time, the vehicle with the 4sp may feel sluggish because of the rev drop-offs - it's not that the the 0-60 time dissappoints the owner, but the feeling of slugishness may disappoint the owner.

But I agree with you, the 4sp vs. 5sp vs. 6sp comparo is made into a much larger deal than it is.

 

it doesnt really matter too much, as long as they have similar final drive gear ratios. 4-5-6 speed.

No, the final drive ratio is not all that matters.

More gears will first off let you get up into the powerband and stay there for fast launches, and secondly will let you stay in that efficient sweet spot when you're cruising around the city for better city mileage. 6 is not just more than 4, it's better.

 

No, the final drive ratio is not all that matters.

More gears will first off let you get up into the powerband and stay there for fast launches, and secondly will let you stay in that efficient sweet spot when you're cruising around the city for better city mileage. 6 is not just more than 4, it's better.

yeah, if you have a 4cyl little car..

so why does the 4 speed silverado get better gas mileage than the 5 speed tundra? Not all configurations but most of them

 

All I know is whoever said that the Pilot can seat 8 is smoking something. Definitely not adults! My in-laws have one and we occasionally ride together. 2 up front 2/3 in the middle, and ONLY 2 kids in the back. It is really too tight for anyone over 5 yrs old in the back row. Seating 8 is like seating 5 in a camaro.

 

yeah, if you have a 4cyl little car..

so why does the 4 speed silverado get better gas mileage than the 5 speed tundra? Not all configurations but most of them

Huh? What does it matter what kind of engine is in the car?

The 4 speed silverado might get better mileage than the Tundra because you're comparing different powertrains. The powertrain in the Silverado is probably more efficient.

If you could compare a Silverado with a 4 speed and one with a 6 speed, that'd be better. Unfortunately that isn't possible right now.

 

I'd have to say that image is probably the driving factor of the upgrade to 6 speeds from 4. Yeah, there are performance advantages (however slight or bright they may be), but the average person probably doesn't know about that. Thus they'll simply go by the number of gears thats in the thing because it sounds cool when they're talking too all their buddies about it.

 

I read an article on Top Gear regarding the LS460 and they were complaining how the transmission kept hunting for the right gear. It couldn't find the right gear ever. Always in the wrong gear.

Personally the GM 4-speeds are great and so is the 4-speed in my mom's Taurus. Absolutely amazing. But to me they are always in the wrong gear and therefore a manual for me for life.

 

There is a very real difference in operations.
For example, I had a 2001 Accord 2.2 4 w/4-speed auto. Later I had a 2003 2.3 4 w/5-speed auto. Granted, there were some advances in VVT tech in the later engine, to the point where something similar to torque could be felt.
There was a world of difference in the driving experience, the 4-speed shifted out of second at about 73 and after that there was no usable power to speak of. Not much fun when trying to merge into high speed traffic.
The 5-speed shifted at about 35, 65, and 90, and it had far more flexible power and it wasn't dead after the 2-3 shift. In fact, the 5-speed 2003 was more flexible than a 3.0 200HP V6 Accord, which was torqueless and needed more gears.
So probably for 80% of drivers, the actual number of gears, ohc vs. ohv, and other items they don't care about other than the car starting and going as pointed, I doubt there's an issue.
For drivability and flexibility there's a big difference.
The acceleration figures for the Equinox 3.4 w/5-speed are similar to an Impala 3.8 w/4-speed, and there're several hundred pounds difference as well as more cajones with the 3.8. The 5-speed makes a big difference.
It's real in the real world, and probably more importantly it's real in the advertising world. :yup:

 

I read an article on Top Gear regarding the LS460 and they were complaining how the transmission kept hunting for the right gear. It couldn't find the right gear ever. Always in the wrong gear.

Ya, 6 speeds will do that. With that many gears any slight change in speed or throttle position will make a different gear more beneficial since the ratios are much closer. It can be rather annoying in traffic (it's awesome under heavy acceleration ). I think that the computer in a lot of 6 speeds needs to be programmed to sometimes not shift if the selected gear is still a pretty close match to optimal.

 

Ya, 6 speeds will do that. With that many gears any slight change in speed or throttle position will make a different gear more beneficial since the ratios are much closer. It can be rather annoying in traffic (it's awesome under heavy acceleration ). I think that the computer in a lot of 6 speeds needs to be programmed to sometimes not shift if the selected gear is still a pretty close match to optimal.

i understand your idea at the end, but (playing devils advocate ) wouldn't that harm advertised fuel economy at all? Even if it ends up being a "better" driving experience, btw- in the saturn aura xr it DOES hold the gear pretty well, at least the tons of miles i put on one.

-Kheiron

 

5 and 6-speed automatics offer a greater overall ration spread, but have less drop between gears.

One of the greatest draw-backs to the 700R4/4L60/4L65/4L70 is the huge drop between 1st and 2nd gear. Nearly every vehicle has great initial acceleration, but without huge amounts of torque, falls flat there after. More gear allows the engine to stay in the meat of the torque curve, while retaining that low rpm high-way cruise.

Aside from size and weight factors, 5 and 6 speed automatics are a better deal.

The I5 Colorado vs. 4.3 S-10 is purely a perception of torque. Unfortunately even though the I5 is a fine engine, it is a psychological barrier and is a turn off to many. Even with a 6-speed, better fuel economy, and better performance, it would still be an I5. A V-8 is the ticket.

 

Under light-medium acceleration, my 4T60 seems like it shifts too early. I wish it would just draw out the shift a little more. It's in 3rd gear in no time.

I could see how it would be annoying having an auto with too many speeds. Computer has too many to pick from and hunts.

 

I really think that more then 6 speeds and the return starts to get too small to marriet the cost to develope and produce transmissions with more gears.

WIth modern day engine tecnhology giving us some very flat torque cruves a 6 speed auto or a 6 speed manual are probably the best routes to go in. I dont just look at things as being the "best" but I take price into consideration. For example the Posche CGT maybe overall a better vehicle then lets say the Corvette C6 Z06 but is it really worth that $430,000, is it $430,000 better?

 

I think you're headline hits the nail on the head. It's "perception". Lexus has now launched 8-speeds. And I think the comment about 6-speeds is on target. I've got a 6-speed in my LS1 '02 Z28. And at 80mph in 6th gear, with cruise control, I'm pulling just around 2000 rpm. Any less and the engine would lug.

 

It all depends on the gears, both in the transmission and the final drive/axle ratio and how they want the vehicle to perform. Some cars with the 6-speed replacing the 4-speed do better on gas, some don't.

 

Slowly starting out from a light, the engine will rev up to probably about 2500 rpm, then shift, and this cycle will repeat until the speed settles off and the transmission can settle in the gear that is the best suited for the chosen cruising speed. Let's assume that this speed is 110 kmph (68 mph). In my truck that would be 4th gear @ 1800 rpm approximately. Now, with a 5 speed transmission, what advantage would it have over a 4-speed in this situation?

For instance, the Malibu SS with the 4 speed auto is at around 2200 RPMs at 110 km/h, while my Impala - which is dramatically slower and has 0.5 liters less of engine displacement - runs at about 1750 RPMs at the same speed. Both cars have 2.92, 1.57, 1.0, and 0.7 in the transmission, and the Malibu SS has a 3.69 final drive while the 2001 Impala has a 2.86.

In the Impala and Malibu's case, and presumably in others, the spread between the 4 speeds is too small and you have to choose between a very high final drive ratio for good performance and mediocre fuel economy or a low final drive ratio for mediocre performance and excellent fuel economy.

A 6 speed auto with the gears properly spaced offers the performance of one and the efficiency of the other with no trade off.

 

For instance, the Malibu SS with the 4 speed auto is at around 2200 RPMs at 110 km/h, while my Impala - which is dramatically slower and has 0.5 liters less of engine displacement - runs at about 1750 RPMs at the same speed. Both cars have 2.92, 1.57, 1.0, and 0.7 in the transmission, and the Malibu SS has a 3.69 final drive while the 2001 Impala has a 2.86.

In the Impala and Malibu's case, and presumably in others, the spread between the 4 speeds is too small and you have to choose between a very high final drive ratio for good performance and mediocre fuel economy or a low final drive ratio for mediocre performance and excellent fuel economy.

A 6 speed auto with the gears properly spaced offers the performance of one and the efficiency of the other with no trade off.

Finally! a good answer, axle ratios/tire sizes have more to do with 6 speed's benifits that the the extra gears.

Allowing the vehicle to cruise at freeway speeds while turning a lower RPM, while still merging on to the freeway at a reasonible rate of acceleration.

Remeber Torque can be multipied, Horsepower can't.

 

go on the track once with a manual six speed versus a 2 speed or a 3 speed auto. you'll get killed, shift so many more times. even with an auto 6 speed..... shift just once for a 2 speed powerglide. and even turbo 350's just shifts twice. 1 time for some people that start in second. you lose what maybe a few 10ths or so while shifting. over the whole period of a race or run. think about it. more consistant with less shifts, sure the power band isnt always hit but it takes less time in the long run. on top of all that. less weight, less parts, lower costs. keep it simple.

 

go on the track once with a manual six speed versus a 2 speed or a 3 speed auto. you'll get killed, shift so many more times. even with an auto 6 speed..... shift just once for a 2 speed powerglide. and even turbo 350's just shifts twice. 1 time for some people that start in second. you lose what maybe a few 10ths or so while shifting. over the whole period of a race or run. think about it. more consistant with less shifts, sure the power band isnt always hit but it takes less time in the long run. on top of all that. less weight, less parts, lower costs. keep it simple.

That is looking at the subject from just one perspective though, yes fewer gears (when you have a good amount of power and torque) is good for drag racing. But what about all of the other forms of racing and the daily commute?

If all cars were built for the drag strip then we would have some really different cars on the road right now.

 

go on the track once with a manual six speed versus a 2 speed or a 3 speed auto. you'll get killed, shift so many more times. even with an auto 6 speed..... shift just once for a 2 speed powerglide. and even turbo 350's just shifts twice. 1 time for some people that start in second. you lose what maybe a few 10ths or so while shifting. over the whole period of a race or run. think about it. more consistant with less shifts, sure the power band isnt always hit but it takes less time in the long run. on top of all that. less weight, less parts, lower costs. keep it simple.

A powerglide is great for performance, especially on the drag strip. But for a family vehicle economy, longevity, and quietness count too. Look at this page:
http://www.race-track.com/news.asp?TOPIC_ID=532
Say you get a powerglide with a 1.76 and 1.00 gears and a 3.42 final drive on something like a Corvette with 245/40R18 tires.

At 65 mph in your top gear, the engine will be running at 2900 RPMs. That's going to be noisy, it's going to guzzle fuel, and running at a constant higher RPM is going to wear on your engine more than a car running at 1600 RPMs at the same speed.

 

Huh? What does it matter what kind of engine is in the car?

The 4 speed silverado might get better mileage than the Tundra because you're comparing different powertrains. The powertrain in the Silverado is probably more efficient.

If you could compare a Silverado with a 4 speed and one with a 6 speed, that'd be better. Unfortunately that isn't possible right now.

While it doesn't quite matter what "kind" of engine is in there, how much torque and for how long it can spread that torque over the rev band most certainly does. Engines that make a fair amount of torque and can hold 80% of that torque over a wide rev range do not "need" alot of gears to perform well. Most small displacement engines (read: 4 bangers), do not make alot of torque nor do they hold that torque over a large rev range. Engines like this NEED more gears to constantly keep the engine in that narrow band of torque.

Honda raced the old RC110 which was a 250cc 6 cylinder bike that had a 9 speed tranny. The engine would rev to 19,000 rpm but would stall below 8500rpm, so all those gears were needed to keep it in a 1000rpm band where the torque was. Now I am sure someone will say that Class 8 trucks like I drive have alot of torque, and that is very true, but all that torque is only available from 1100-1600rpm. That is why you see big trucks fitted with trannies that have anywhere from 10-18 speeds.