MarcJD

Sorry if these are stupid questions, but:

1) Why do they call our automatics 4 Speeds when they are in fact 3 Speeds and overdrive?

2) Why do automatics always come in less "speeds" than manuals? Is it because the automatic transmission would wear out too quick with more gears, or because it would be too expensive to add another gear to it? What is the deal? Wouldn't another gear, especially with the new 2002 model coming out add performance?

3) Am I wrong in thinking that overdrive works differently in different cars? It seems as though my past experience has been that overdrive only kicks in after 3rd gear on the freeway. However, when I switch it from off to on or vice versa in the city I see my RPMs change.

These are just questions I have been curious about and thought would be interesting to hear other people's perspectives. I don't really need any answers.

DA-MAX

iTrader: (10)

why when some of us auto guys race they say to turn off the OD?? in the owners manual it suggests OD be kept on if you exceed 55, so wouldn't you be hurting the car or something by keeping it in OD when at the track(since most traps are 80+ mph)?? I never got this....

MarcJD

I think the logic of this is that over 55 or so your RPMs start to get a little higher which is harder on the engine. However, if you only do every so often there should be absolutely no problem with it. People with manuals usually run the engine harder since they would normally wait until the RPMs were higher before shifting than us folk with automatics, but I haven't heard of their engines going bad or anything. Do these engines go bad?

I wish my car would allow me to keep it off since I drive primarily around the city and on the freeway through the city, but I have to turn it off every time I turn the car on.

MarcJD

Sorry, to answer your first question is that your acceleration will be much better with overdrive off and that is why they tell you to keep it off when racing. Especially since overdrive throws the gear ratio below 1.0, which is great for grandma and grandpa on the freeway driving up to Canada for prescription drugs, but not good for us folk that want more power at that speed range. Nonetheless, I don't think having overdrive off would make that much of a difference (I may be wrong, it has already happened twice this year) when you are racing since it will probably never be engaged since you are flooring it most likely and asking the car for the power. Since it wants to give you that power overdrive shouldn't be engaged...just like when you step on it while driving on the freeway and it downshifts out of overdrive.

niceorange

1) Overdrive is another gear. An overdrive gear is usually any gear with a ratio less than 1.00, typically .80 or less. By switching off your overdrive, you force your tranny to stay in 3rd gear at a 1.00 ratio, which is fine, but it hurts gas milage as the engine turns more RPMs at that range.

2) Automatics dont need as many gears as a manual because the torque converter transforms a lot of horsepower into torque, and therefore can run fine on fewer gears with larger gear spacing. Because of the clutch in manuals, the transmission must be set up so that at any speed, the engine can run in its best power band in one of the gears. The Maxima could use a 5 speed auto like many other cars have now, but they are more expensive, and Nissan is cheap. Plus, on many 5 speed autos, the 5th gear is an extra high OD (3 speed + 2 ODs)

3) Every tranny runs different, and different cars run theirs different due to the computer. For example, my Crown Vic Police Interceptor has no rev limiter because it is a police car. It will go to redline in any gear, so it has tremendous gear range (75 in second). A civilian Crown Vic will not, and tops out at different speeds in each gear. Also, OD does not only turn on on the highway, in fact, in many cars the tranny will go to OD even in the 30 mph range, especially if you are coasting or barely accelerating. The problem is that when you go to accelerate, the car boggs at that speed in OD, and therefore the tranny will kick into second again. When passing on the highway, the car will kick into second below around 65 (depends on the car), then into third, then back to OD as you let off the throttle.

And on the track:

The reason you should not run OD on the track is because depending on the car, not running OD will increase the tranny shift point RPMs, and therefore give you faster track times. Basically your car will run as fast in 3rd as it will in 4th (OD), but use more gas. If you check the top speed ratings of most sports cars, the top speed comes at redline in their sub-overdrive gear, because often the engine cant power to redline in OD.

pmar

Why a 6-speed manual? Marketing, that's all. Now all the luxury cars have 5-speed automatics or tiptronics if you will.

4-spd auto is neither here nor there. They are annoying in cars like Sentras where it can't keep it in 4th on the highway if going uphill. Then the tranny hunts back and forth between 4th and 3rd, hence lock it out.

Remember, BMW does not have overdrive. Every top gear is 11, even the 6-speed 540i. Yet they accomplish nearly 30 mpg and quick acceleration. That's engineering. It's been said by people here they wish Maxima had a 6th gear because it would lower the rpms, that 5th didn't do it. That's not the purpose of having a 6th speed. It's kinda like saying why a 12-speed instead of 10 for cycles.

max'n out

The reason auto's have 4 speeds is becuase it is asumed that non racers or old people use them and could care less. It allows cheaper cars with lower top speed. Now the 2002 bmw 740i is going to come with a 6 speed auto(which is the tranny im gonna put in mine)why? beacuse they can run the gears closer and still smooth. This allows it to be the "ultimate driving machine". Making it faster smoother and quicker to acceclerate. But it also drives up the cost. In part I hope this helps

dwapenyi

iTrader: (3)

The main reason autos have less gears than manuals is simple:

cost

A 4 speed auto tranny costs more than a 5 speed manual to build. The auto tranny is an incredibly sophisticated piece of work. The manual tranny, compared to the auto, is quite simple. The more gears a car has, the better, period. The greater number of gears enables the tranny to take better advantage of the engine's output. That's why 5 speed maxes are faster then the auto maxes. The automotive industry has recently been able to make 5 speed autos. Where do you see them?? In expensive cars like Benzes and Jaguars, because their cost is so high you only see them in premium cars for now. BMW's next 7 series will have the world's first 6 speed auto. Incredible. Now that the auto industry is able to make auto trannies with the smae number of gears as manual trannies, the performance difference will disappear. Looks like the manual tranny is well on its way to becoming obsolete.

The ulitmate transmission is the CVT, or the continuously variable transmission. Way better than a manual because it is like having a gazillion gears all optimized for the torque curve of the car. One thing about the CVT, tho, it'll make your car sound like a vacuum cleaner because the tranny will let your car rev up to its optimum torque rpm, like 3500, and just hold it there. Meanwhile your car is picking up speed better than any other tranny ever could get it to.

DW

niceorange

NO! An automatic is not slower than a manual because of its gears, it is slower than a manual because of power loss in the torque converter generated by the actual process of converting horsepower to torque. In fact, automatics shift much quicker than the best drivers, and yet are still slower, regardless of gears. The CVT is not the ultimate transmission, it has massive amounts of slip due to the belt system needed. Also, it is a maintenance nightmare in a car, it works in snowmobiles, only because they are light and its cold out. Run a snowmobile above 50 degrees, you'll see what a CVT's problems are. The ultimate transmission is probably the Ferrari triptronic: A manual, with clutching and gearing controlled by a computer, for shifts in 1000th of a second

A-Ron Max

This probably wouldn't work, but how does this idea sound:

to get a better off the line launch on an auto, make it have a 1st gear that revs up really fast and redlines at like 15 MPH, this would help the car get a quicker launch and into the higher RPM's and maybe help it keep up w/some of the manual trans. cars. Sound like it'd work?

MarcJD

I have a question...another one that is. I keep hearing about these automatic manuals in the high-end cars. Well, what is the big difference between having a manual and automatically shifting it like a manual and these things? I know some of them will automatically shift for you if you don't, but what else is the deal? Do they just shift better?

Eric L.

The OD button on your shifter is an on/off switch that has an "in" and "out" position right? So, why do you need to turn off OD each time you start the car? Doesn't the switch stay "out" for OD off? I might be wrong on this, since I hear that newer Maximas have a toggle switch for OD, and not the two position switch.

As for leaving OD on or off, it really doesn't matter for the engine. It will affect your fuel economy though (turning off OD lowers fuel mileage). Perhaps over the long run the higher RPMS with OD off might cause a little extra wear on the engine, but I can't imagine it would be that much.

MarcJD

That is what I was used to with all of the other Nissans I have driven, which have been many. However, with my '98 I have to turn it off every time I start the car--very annoying, but something I can live with.

dwapenyi

iTrader: (3)

Your reasons are valid. So are mine. Auto shifts faster, but that difference does not justify the total performance difference between an auto and a manual. The performance difference is also due to a car having 4 gears to use instead of 5. More gears the better. You cannot tell me that a car with a 4 speed manual and a car with a 5 speed manual will accelerate the same. Same if you compare a 3 speed auto to a 4 speed auto. They won't. The car with more gears will accelerate faster.

The CVT is the ultimate, once the technology matures.

Your points are addressing the fact that the auto industry can't build a good CVT yet.


ZAs for the automatically shifting manual in the ferrari's, those are really cool. I forgot about those. But the auto industry doesn't seem to be going that way. Maybe there's a reason you only see it in a Ferrari.

DW

DW

pmar

Auto manufacturing is all about saving money. More costly to give you a 6 instead of 5-spd. Why does a Maxima use the same door handle as a sentra? Why did Ford go with rear drum brakes in the current Taurus when they were all discs for 2 generations previous? Why do only some cars use struts to hold the hood up? Let's see if Altima steps up to the plate with gas charged struts holding the hood up over that 3.5L bad-boy.

Dang, more gears = better, and not subject to debate. Just better. Madison Ave. wins again!

A lot more shifting to get to whichever gear is 1:1, be it 5th in a Max or 6th in a BMW. A lot more clutching too and wear and tear if you've got an abuser in the family.

6-spd manual is a marketing gimmick, Celica has had it for how many years now? But in 2002, everyone and their sister is getting it. Do I want it? Sure. Will it make the car better, period? No.

Jeff92se

iTrader: (82)

6-speed not better? I disagree. Your probably too young but Mustangs used to have 3-sp manuals. 4 speed sticks were the rage. Then 5 speeds. You mean 5 speeds didn't make cars better?? Why would a 5 speed make a 4 speed better but not a 6 speed vs a 5 speed? The more torque multiplication, the better. As far as Celicas having 6-speeds, well there as been a 6sp kit for VW for about 5 years now and Corvettes has had a 6sp for about that long also. And for what it's worth, semis have about 10-12 gears.

pmar

Too young, even though you didn't mean it that way I'll take it as a compliment. My first car was a 250 I6, 2-spd auto Poncho LeMans. It shifted smoother than my friend's 2001 Sentra which is a 4-spd auto.

FYI a tractor avgs. about 350 hp and 1900 ft-lbs torque. In the old days they all had 18-speed manuals with double clutches. Today you can have anything you want, from 6 to 18 speeds, either auto or manual. Ever ride in a 2001 Prevost? Those puppies are assembled in St. Anne Quebec and it's a smooth cruise and not subject to abuse by older drivers which are more and more common these days. If you can get away with 6 gears instead of 18, and your business is to drive 16 hours a day, wouldn't you choose simplicity and lesser maintenance? Take a look for yourself. Let me tell you gramps *lol* trucking is about making money, not having fun. Nobody wants an 18-speed if they can get away with less.

http://www.truck.eaton.com/na/spec_p.../transmission/

Do I want a 6-speed manual, yes I do. Is it better? Not really. And if you add any more it's overkill and wear-and-tear. If the Maxima put out 1411 ft-lbs of torque and needed to haul 35,000 lbs, then yes it may need a 10-speed manual. No, more is not necessarily better. Oops, unless your field is marketing.

MarcJD

Did I inadvertently start a debate here by starting this thread? Oh well, I am curious as to the "answer" you are debating. Wouldn't a true 4 speed Maxima be better than a 3 speed with overdrive? Or not?

dwapenyi

iTrader: (3)

I can understand it, but I can't fully explain it to you. More gears, the better. Marketing gimmick? I don't think so. More than 90% of a car product line (in the US) is auto based, like the Maxima. Of all the Maximas in the US, only about 7% or less are stick. Where's the gimmick in that?

You know where the gimmick is?? In all those auto sticks that shift like manuals, like the porsche triptronic, the chrysler auto-stick, etc. All autos have always had those capabilities, like the auotmax, but using them was cumbersome. They just re-positioned the gear selector to make it feel more like you're driving a manual, when you're not.

DW

MarcJD

I think a true 4 speed w/overdrive would be a marketing gimmick and a very nice enhancement. Has anyone tried throwing a different tranny in their Maxima?

Jeff92se

iTrader: (82)

What is your defination of "better"?? Are you saying a 4-speed maxima would be better than a 5-sp? Then are you saying a 3 sp maxima would better than a 4-speed?
At what point does it transform from a good thing into a marketing thing? In your explaination, a 4 speed was all marketing becuase you can get along just as well with the 3-sp manual correct?

So all the hp increases must be marketing becuase you can get along just as well with 225 hp vs 260hp correct? 260hp should be more wear and tear because people will drive it harder correct?? A 2 valve, pushrod I6 is as about as simple as it gets, but we have 4 and 5 valve engines, variable intake,cam and cam phasing technology, electronic ignition, turbos,supercharges etc... All of these are 100x more complicated than a that old I6. But they are here and I guess it's all marketing by your defination beucase we cold all get along without it but you would still want it


If the 6-sp is all marketing, then why in the hell do you want one?

pmar

Nobody says it's all bad to want something that's show. Why do folks pay extra for metallic paint on German cars? The whole purpose of the tranny and having gears is the "step" between each one. Take a look at the 2002 RS-X. From 1st to top gear, the range is identical, though the Type S is a 6-speed. We're talking identical in 1st, reverse, and 5th vs. 6th respectively. Final drive identical. So where's the function? You just have to shift once more and clutch once more to reach the same point. The steps are smaller in the 6th speed. If you followed my link you'd have a simple understanding of that.

In the old days there were cars that actually had only 75-90 hp and were 4 speeds. If you put the car in the wrong gear at the wrong speed the motor would lug very badly. Having more gears and smaller steps would help in that situation. The 5th speed was added for overdrive purposes. A 190 hp Maxima is pretty forgiving, you could be going 20-25 in 4th and though it's not good for the motor it wouldn't even come close to stalling. I see ALOT of 4th to 6th shifts in the 6-speed cars.

Nobody says you have to understand everything to like it, you can just like a 6-speed for the h*** of it if you want. But you can't just say it's better period, because it's not.

bolido2000

Although the range is equal between RSX, and the RSX type S; doesn't the 6 speed mean that the gearing from 1st to 5th is closer, thus making acceleration faster?

Also, I have always wondered whats the difference between the sequential gearbox (a la Ferrari) and the automanual in same cars that let you redline as much as you want??
I think ferrari is basically a manual with a computer controlled clutch, so what is the essantial difference between auto and manual?? Is not that in one you choose the gear and the other one a computer does it for you, right?

ru4real

iTrader: (3)

The automatically shifted manual transmission does not only show up in the Ferrari. I'm an engineer for an automotive supplier, and I know of an Opel (GM) transmission for Europe that does the same thing. Electro-mechanical actuators operate the clutch and shifter. This type of transmission could become very widespread in the future, since it combines the simplicity, fuel economy and efficiency of a manual transmission (no torque converter or complex double planetary geartrain) with the potentially quick shifting of actuators. The automotive industry's drive towards 42-volt electrical systems and increased fuel economy should help it along.

dwapenyi

iTrader: (3)

There are certain assumptions in this argument that more speeds are better;

1. We assume that the gears are chosen to optimize the performance characteristics of a car. When you have a 5 speed, you can make 4 gears to "get the car going" and leave 5th for the relaxation gear. With a 6 speed, you can use 5 gears to get going etc. I checked out the Acura RSX page and saw what you were getting at. In the 5 speed, 1st and 5th are identical to 1st and 6th gear in the 6 speed. This all follows along with what I'm saying. With a 6 speed, your top speed won't be better, given the same engine, but your acceleration will be, in the 6 speed.

If you compare a 1 speed to a 5 speed, you can appreciate it better. In a 1 speed car, that one gear will take the car from 0 to 60 mph. It'll be very slow getting there, and fuel economy will suck. By having more gears, you keep your car operating at its most optimum rpm, therefore producing the best power and economy.

More gears are better. Period. CVT is ultimate.

niceorange

Well a whole lot of good points have been made here, let me see....

I think that a lot of you are presuming that versatility in a transmission equals performance. For example the CVT I posted about earlier is a good tranny when power is not of the abundance. Also, more gears is better when you need more power use. This was brought up in the post about 18 speed Semis. When you are towing a large load, or are underpowered, you want to be able to shift with very small change in RPM. This is what 18 speeds does for trucks, and what a CVT does by nature as the transmission speeds up the vehicle, not the engine rpms.

Now where it gets interesting is when humans are involved. In theory, if gears can be shifted instantly and without any loss of power, than the more the merrier. This is why Dwapenyi is so attached to the CVT. However, when you have gear shift delays, then you also have loss of acceleration during that delay. The more delays, the more acceleration loss, as it is physically impossible to accelerate when a clutch is in, or when an auto is shifting.

When you have an underpowered engine, with a small powerband, you want more gears because the engine just cant keep up with the big gear spacing. The 02' Maxima has 260hp, and thats is a huge amount. It also has a huge torque band, and because of that, it can use 4 speeds with more efficiency than most other cars. I would personally have been happier with an extra 6th gear for a super high OD, and great fuel economy. Close ratio's are ok, but if you need to hit 3rd gear before 60, kiss the 0-60 times goodbye. That shift is good for a few tenths of a second, believe it or not.

Now there has also been a lot of discussion about the benefits of different speed autos vs manuals. Again you can not compare an auto and manual because the auto transmission generates more torque, and the manual is a direct power link.

When you guys want performance, you really just want a good first and second, because most of us dont worry much about accelerating in overdrive anyways.

carnal_c30

iTrader: (38)

well most autos suck at shifting so they offer the tiptronic type shift.. the clutchless shift... it helps in alot of the luxury cars cuz the gearing and shift programs are for comfort and smoothness... the 5spd on the TL/CL actually performs perfect redline shifts when its pushed... its a great tranny
besides that whole auto/stick kinda deal is for old people or people whon dont know how to drive stick to make them feel worthy

yea and 6 speeds are gimmicks in a performance point of view... but they do help the car get better fuel economy hahaha

dwapenyi

iTrader: (3)

Interesting summary, but not quite what I was thinking. I think the loss in performance between shifts is negligible when you have 5 or 6 gears. It'ds only when you get to truck trannies with 10 to 18 gears that the shifting loss gets considerable.

If you had 3 cars (take a 200 HP 6 cylinder) all with the same engine and body weight, but 3 different trannies, this is what things would be like;

The car with the CVT would be the fastest and most economical.

The car with the 5 speed automatic and the 5 speed manual would be almost identical. Case in point, the Mercedes Benz CLK 320. You can get it with a 5 speed manual or a 5 speed auto. Acceleration times are the same. The advantage of faster shifts of the auto are negated by the not so efficient as the manual torque conversion.

The CVT would be the fastest, not only because of not shifting, but more so because it can hold the engine at peak torque during the entire acceleration run (like auto boxes do wtih their torque converter, to an extent). If the car develops its peak torque at 3500 rpm, then the CVT holds it there. You get peak torque at 30 mph, at 31 mph, 33 mph, etc, for the entrie acceleration run.

With the 5 speed auto and manaul, you get peak torque only at one point in each gear, like say 20 mph in 1st, 35 mph in second, you get the idea. The reason more gears are better is because you get more opportunities to use that peak torque of the engine.

As for my attachment to the CVT, I like te concept on paper, but I think its ideal place would be in 2 markets, Hi economy cars like Honda Civics that get up to 40 mpg, and trucks, where economy is a majore priority, after load. Of course it may take a while for the auto industry to build a CVT to handle truck work.

You know, this discussion got me to thinking, and I think I'm getting the other points about more gears not being better. If a 7 or 8 speed manual were introduced, would there be a market for it?? Doubt it, cause that many gears makes hing cumbersome, as truck drivers must experience. The car would perform better with more gears, but the driver experience may not be as "fun"

sudden1

I owned a '66 Mustang GT with a 3-sp manual... I had very well developed left calf muscles...

Cutler

iTrader: (3)

They made a 66 GT, I gotta on that one and one for the grave digging

Ninos_Maxima

iTrader: (5)

Just look at your od button, stare it, and give it hard looks. Go to your local junk yard, buy a 5spd lsd tranny, then go look at it and give it hard looks again, this time, Ripp the damn suker out in a rage of complete blockage to the senses. My 0.2 cents

Barc

iTrader: (2)

Ford produced the GT from 65 - 68 (GT was a package that included different options like exhaust, front disc brakes, etc. I think you could get the Hi-Po engine with the 4V (4 Venturi or 4 bbl carb) without the GT option in those years...). Then from 82 on the GT was available.

Here's a link (I know, it's not directly from Ford so some won't believe it but do a little research for yourself): http://www.etconnect.com/gt/featured.htm It has a few pics of various GTs.

Back to transmissions...

mzmtg

iTrader: (11)

The amount of ignorance in this thread makes my head hurt.

SteVTEC

I'm too lazy to go back and own pretty much every post from like 4 years ago though, and for people that might not even be here anymore.

deezo

iTrader: (3)

I can't believe this thread was brought back from 3 years ago.

ru4real

iTrader: (3)

^I agree.
I haven't been on here for a long time and I was wondering who resurrected a thread from 2001.

My Maxima is for sale

dmbmaxima2k2

iTrader: (1)

why you selling the maxy. what else is new.

ru4real

iTrader: (3)

Uh, I realized it would never be as fast as deezo's, that's why I'm selling.
How about you, last I knew, you had your blue 2k2 and I thought you were getting an FX45!?

PM me

deezo

iTrader: (3)

Whattup mang?

chenzarino

iTrader: (2)

What part of ***Overdrive IS a gear*** was explained in Chinese?