Guys/Gals. I've been debating with myself about this issue for eons and could never come up with a good conclusion so let's hear what you have to say.

(Scenario: Track)

How is it that a 6sp transmission is better than a 5? Wouldn't the extra time it takes to shift 1 more time rob you of some precious time? Then if that were the case, wouldn't a 3 or 4 speed be more beneficial?

I know having more gears helps you maximize the power of the engine by staying in the right gear at the right time. However, when you launch from a stop you always go 1-2-3(-4-5-6) as you reach top speed. So technically you're already maximizing the powerband at that point.

(Scenario: Every day driving)

A lot of us here drive in the city where chances are you'll never reach 5th gear due to stop-go traffic. Would you agree that a 6sp won't make sense at all?

(General Question)

To sum it up, what exactly is the advantage of having more than 4/5 gears when it comes to a) Track racing and b) Every day driving?

I just read about the new 7spd BMW and i can't imagine how you could actually make use of all those gears efficiently in any of the above two scenarios.

 

basically, the 6th gear on the max acts as an extra overdrive gear. supposedly they reworked all of the gears but i'm not sure on that one. anyway, the main reason for it is for highway driving. at the track you'll never see 5th or 6th gear (a lot of guys don't even shift to 4th). in the city you could cruise in 6th i suppose, although 5th might be a better choice. it's main purpose is to get the revs down on the parkway. as it is in my 4th gen 5 spd crusing on the parkway at about 80 mph is roughly 3250 rpms. having a 6th gear just conserves fuel by dropping the rpms down as you cruise.

 

So having more gears is more of a question on fuel economy rather than performance then am i correct?

Then if that's the case why does everyone seem to goo over manual transmissions with more gears?

(p.s. i'm talking generally, not just for Maxima's)

 

Because most of them have closer gear ratios which does two things:
Allow you to shift w/o dropping out of your powerband,
and helps you get to your powerband earlier by reving faster.

Some companies add a 6th speed as a gimmick when it's really just an extra overdrive gear.

Closer gear ratios have been known to achieve faster acceleration.

I certainly hope the new 2k2's are not just an additional gear but actually have closer ratios, supposedly it is so.

 

So in stop and go traffic/driving it's basically useless having more than 4 gears then?

People seem to be saying the reason the 2k2 Alt is quick is because it doesn't have to shift one more gear.

I have an auto which is basically a 3spd+OD. It doesn't rev as fast as a manual i would think but once i get in 3rd i'm usually where the power is at it's peak and i can easily reach speeds upwards of 85mph w/o having to even see 4th gear and i'd still be at the peak of the HP/TQ curve.

 

Okay I got this one...
It's all about mechanical advantage. You've ridden a ten speed bike right? It's a lot easier to pedal in the low gear than in the high gear. Lower gears mean more torque multiplication. It's similar to using a longer lever to move something. I'd break it down more but you'd be better off to go to a search engine and type in "mechanical advantage." Basically, lower gears give better torque multiplication because of various rules and relationships in Physics with torque, force, work, distance and leverage. If you have a 5spd, and you want more torque multiplication in 1st-3rd gear, you have two choices:

1) Get a lower axle ratio
2) Make 1st, 2nd and 3rd lower gears

Getting a lower gear ratio will make all your gears lower, hence higher RPM per mph = lower gas mileage.

Making 1st-3rd lower means you have to space them out more, this means that when you shift at the top of your powerband, you won't be in your powerband in the next gear, you'll be below it because the gear ratios are spaced much wider. The solution is to add another gear, this way, you can enjoy a lower 1st, 2nd, 3rd, even fourth gear without having gear spacing so wide that you drop out of your powerband everytime you shift. Ideally, a transmission would have an infinite number of gears so that the engine is ALWAYS at it's peak efficiency for cruising or peak power for acceleration. This isn't possible, so they make close-ratio, several-speed transmissions and simply make the engine's powerband a little wider.

 

Interesting

How about the ratio's? When a gear is set at 1:1 how exactly does that relate to engine speed and whatnot?

Additionally, taking your fact about "staying in the powerband through proper and close gearing" into consideration, given the facts:

a) 5/6spd needs to hit 4th gear to reach 60mph
b) 4spd can stay in 3rd gear
c) 2/3spd can probably just keep it in 2nd

Then theoretically couldn't it also be said that at their respective 1:1 (or close) ratio's that they're they're right smack in the powerband (peak)?

I mean, from a strictly "Need to get to 60mph" standpoint, wouldn't lower gears be more efficient performance-wise because you negate the need to upshift (which is usually due to you reaching the rev limiter or you having just gone beyond the good range in the powerband)?

 

Did someone say CVT in the new A6

DW

 

Or the lowly Honda Civic HX

 

A close ratio transmission has gears with very close ratios, hence the name. The shorter the gear, the larger the torque multiplier. The engine makes a specific amount of power at the crank, it goes through the transmission where power transfers through the gears and is output at the driveshaft. In 1st gear, if drive all the way up to redline, the car would redline at XXXX rpm, but because of the gears while the engine is spinning at redline, the driveshaft would spin much slower.

Lets say:
1 gear = 4:1
2 gear = 2:1
3 gear = 1:1
4 gear = .8:1
5 gear = .6:1
Final drive = 3:1
Engine redline = 10,000 rpm

wiht those numbers, at redline in 1st gear the engine is spinning at 10000rpms, but the drive shaft would spin only at 833.33 rpms
10,000/4*3 = 833.33

if u upshift to second gear, at redline of the engine, the driveshaft would spin at 1666.67rpms

since the driveshaft is directly related to the rpm of the wheels, it gives u a sense of what speed the car is at at the top of each gear. this would be where the top speed in each gear comes from. the engine reaches redline, and the rate at which the driveshaft is spinning is related to the speed of the car.

on a 2k2 maxima, a close ratio 6spd is almost nullified by the fact that the car already has gobs of torque and doesnt really require the close ratio gears, because it wouldnt need all the torque multipliers. The torque multiplier works like this, same example as a bicycle, if u put the bike into the last gear, and try to move from a stop, it gets really hard to get going, but if u put the bike into a lower gear, it gets really easy to get moving, the amount of force ur legs put out hasnt changed, but has been multiplied by the gears on the bike. now if u try to go at top speed in the lowest gear u would find it extremely difficult, bc your legs would only move so fast, like the redline on a car, but if u were in the higher gear u could pedal at teh same rate and go much faster. if u look at teh gears on a bicycle, the lowest gear is the combination of the largest one in front and the largest one in back, top gear would the the smallest in front and smallest in back. The gears in teh front act as teh gear ratios and the ones in back act as teh final drive.

ah nutz i lost my train of thought.

 

ok let me try again.
on a car with a very narrow powerband, meaning not much low rpm torque, like a civic si, its power doesnt start until it hits VTEC, about 5500rpms. To make up for the lack of down low torque, u would want a very short first gear so that it can take advantage of a large torque multiplier, and get the revs up faster. once its in its powerband 5500-redline, u want each shift to land u within those rpms. if u shift at redline in 1st u want to land above 5500 in 2nd and so on for each gear. if the transmission wasnt matched up properly to the powerband, it would fall out of its powerband and make the car slower.

Now begins the problem. the 2k2 maxima needs to shift into 4th gear to finish the QM, while the 2k2 altima needs only to be in 3rd, and yet they yield very similar times. On a car with traction problems in the lower gears and with that much torque i think the 6spd on the 2k2 was a selling point. A close ratio transmission isnt really required on cars with broad powerbands.

as for the 1:1 ratio, most cars with their powerbands in the upper rpms, and 5spd transmissions, 3rd gear is usually the 1:1. Ask any 5spd maxima ownner and ask what their winning gear is.

 

Excellent thread. Thanks for all the info guys.

 

i forgot about axle ratio, it just works as another multiplier.

 

Dayum!!!

On a Honduh Forum at this point there would be so damned much misinformation that I would spend the next 2 pages clearing all of it up. I would get flamed in the process because some people get mad when they're wrong and then that would be a mess too. Finally, I would get the point across, but it would require reading 2 pages of nonsense, 2 pages of flames, and then one long-azz post by me where the truth finally comes out and people understand!



On Maxima.org people already know what the hell they're talking about and by the time I get to the thread everything has been covered so completely and thoroughly that there's really nothing left for me to post so I end up going off on some tangent about how dumb a lot of Honduh owners are!



You Guys ROCK!!!

 

No my friend, you rock. Sorry for the delay, my computer at home is fubar with a ton of .DLL errors. I have to reformat the hoser sometime soon, then I'll be back up to 11 or so posts per day.

Oh, and JUST WHORING THROUGH!