5 speed vs 6 speed

[Gotian]

I dont know if this has been discussed before, but i know this has been on my mind. As the title suggests this is about 5 speed transmissions and 6 speed transmissions.

Some cars I understand why they require a 6 speed, like the 350Z or RX-8 for example. They are track cars, designed for the course which they live and breathe for. They use the 6th gear to have more room in there powerband to get up and go. They dont have enormous power like muscle cars do (which they also use 6 gears) but they have the aero dynamics to take advantage of the 6th gear. but now other cars are using a 6 speed transmission and I dont understand why.

For example lets take my car, It has 180 HP with a top speed of 148 and it's a 5 speed. As far as the top speed goes, i would probably need to be in a vaccume or have alot more power to get there, cause my aerodynamics suck.
But my car utilizes every inch of the 5 speed transmission and kicks itself from 0-60 in 6.3 sec. and has a 1/4 (best ive seen) of 14.8. Now the GLI (not the new one, but the same gen as my car) Has the same ammount of horsepower but is a 6 speed, and it seems to lack in performance. It's 0-60 has suffered a loss to now 6.7 and the 1/4 seems to have slowed to 15.2 (again best i've seen) and on top of that the ecu is now limited to 130 and if you take off the limiter the drag speed wouldnt be much higher than mine.

Now all over the place companies are putting 6 speed transmissions in their vehicles, I just dont understand why. The SVT focus, i saw one the other day, has a 6 speed transmission and it makes me think, why? So does the new Civic SI (which was fine just as a 5 speed) The sentra SER Spec V also has a 6 speed. My train of thought when it comes to these vehicles are the following:
These cars are not track oriented and are good for things like autocrossing where you only hit 3rd gear maybe once out of every 10 events, so the car stays in the peak of it's power band most of the time. They dont have an enormous ammount of power like muscle cars to need a way for the engine to relax and not waste so much gas so why have a 6th gear?

Just to let you guys know this is my own opinion and I would like to hear your opinions or explainations cause to me it doesnt make much sense. So thanks and I await your responses.

[-Jayson-]

well the SVT Focus was made as a track/autocross car, thats why it got a 6 speed.

6 speed for one reason, its the new car feature. No one really needs a 6 speed, but people like to say they have a 6 speed.

But you forgot 6 and 7 speed automatics. I dont see a problem with them at all. Mainly because they do improve gas mileage and you dont have to shift them so you cant slow the car down by adding more gears to shift, it just goes faster.

[Gotian]

Originally Posted by -Jayson-

well the SVT Focus was made as a track/autocross car, thats why it got a 6 speed.

6 speed for one reason, its the new car feature. No one really needs a 6 speed, but people like to say they have a 6 speed.

But you forgot 6 and 7 speed automatics. I dont see a problem with them at all. Mainly because they do improve gas mileage and you dont have to shift them so you cant slow the car down by adding more gears to shift, it just goes faster.

a car doesnt neccessarilly get fast by adding another gear, my point on that was made when I compared my car with the same generation GLI. And they dont neccessarilly save gas either, both jettas get the same gas milage.

[VR43000GT]

My earlier take on transmissions was kind of the less power you had the more gears were nessecary (most of the time). They used to have the 3 on the tree, then the four on the floor for a lot of those old muscle cars that would have just lost time if they had more gears since they had so much power and all that shifting would have just added more acceleration time. However, now you see 500hp V8 Corvettes with 6 speeds. I don't know if the first four gears are like those of the old muscle cars and #'s 5 and 6 are just cruising gears to save gas, and your timing chain and what not.

[mason_RsX]

Between the Legacy and my GSR they both desperately need a 6th gear only for fuel economy reasons...The ratios between 1-5 are so close (for obvious reasons *cough* no torque until 4000rpm) that I will be on the highway doing 120km/h (74mp/h?) at 3500-4000 which for both cars is so bad for my fuel economy

For both cars I would love to have a tall 6th gear so I could maintain great fuel economy on the highway, and when I want to pass I can just downshift to 5th.....but for both vehicles company cheapness came into play...Subaru didn't want to up the cost of the Legacy by putting the 6speed from the STi in, and ditto for GSR - Type R

[Sleepr awd]

i agree, cars that have more torque don't need more gears, my car is beautify w/ 5 and it is responsive and drives sportily.

cars like the SI, del sol SI, rsx, GTS celica NEED that extra gear b/c their power is all up top. they have very small amounts of torque so when the driver wants to get some power and acceleration out of it, he can drop 2 gears from a cruise and get the power band fairly high.

I did race a spec-v and it has rated 20crank hp less and 20 less wtq, and also weighs 400lbs less. the numbers say i should have lost, but i have better gearing since i don't have to shift as often.

all i all, i wouldn't mind an extra gear, but you don't need it. might just be b/c of the new 70mph speed limits different states have. gas mileage doesn't quite crack up to what it is supposed to be, so they add another gear and keep those rpms low

[turtlecrxsi]

Originally Posted by Elchicoloco86

i agree, cars that have more torque don't need more gears, my car is beautify w/ 5 and it is responsive and drives sportily.

cars like the SI, del sol SI, rsx, GTS celica NEED that extra gear b/c their power is all up top. they have very small amounts of torque so when the driver wants to get some power and acceleration out of it, he can drop 2 gears from a cruise and get the power band fairly high.

I did race a spec-v and it has rated 20crank hp less and 20 less wtq, and also weighs 400lbs less. the numbers say i should have lost, but i have better gearing since i don't have to shift as often.

all i all, i wouldn't mind an extra gear, but you don't need it. might just be b/c of the new 70mph speed limits different states have. gas mileage doesn't quite crack up to what it is supposed to be, so they add another gear and keep those rpms low

I agree. The 6th gear in a lot of these high strung 4 cylinder cars seems necessary just to keep the rpms lower at speeds higher than say 80mph. I know in my 5 speed CRX Si 80mph is over 4200rpms. A 6th gear would put me comfortably at 2800-3000 rpms where I normally would be cruising in 5th at around 60mph. Make sense? But being in 5th gear at 4000 rpms requires no downshift, just hit the go pedal and hope for the best... haha.

[Gotian]

The gas milage thing doesnt always add up to me, Example, I have 5 gears and I drove to ft myers which is about 200 miles form miami and I went there and back the same day. I did this on one tank of gas going about 100mph the whole way through and averaged more than 400 miles. when Im going 100 my rpms are at about 3500. so I didnt seem to waste much gas.

[Polygon]

The reason for adding another gear would be for faster acceleration and higher top speed. This given that you have enough power for the top end and closer gear ratios for the better acceleration.

[CBFryman]

^^exactly. Application dependant. New 500hp 6 speed vs old 500hp 4 speed is the new one can stay in its power band better and has the areodynamics ofr a higher top speed.

[Gotian]

Originally Posted by CBFryman

^^exactly. Application dependant. New 500hp 6 speed vs old 500hp 4 speed is the new one can stay in its power band better and has the areodynamics ofr a higher top speed.

okay but i was referrign to cars with smaller ammounts of power, within the 200 range, like my car, the faster acceleration is not entirely true as in the case of my car and the civic SI. Like you said you have to have the closer gear ratio's but if you indeed do have the closer gear rations than that will limit your top speed to a lower amount, say from being 140 with wider gears on a 5 speed to 130 with a 6 speed but with closer gears.

[Polygon]

I see your point, and you're right. For cars with low horsepower it is more about marketing than performance.

[CBFryman]

slower acceleration is due to more shifts

[2000LS1Z28]

6 gears is typically for a higher gear ratio. You can have very tightly spaced gearing, and also give the enthusiast better fuel economy. Heck some of the old manual transmissions were 3 speeds.

Also I believe the new Jetta is heavier then the old one, so that could account for the slower numbers generated.

Heck some of the old GTI's had close to your car's performance numbers despite lacking your car's power, just because they were soo light. VW's been porking up their cars. I can't believe how heavy the R32 was. Cushy ride though.

[-The Stig-]

Most six-speed transmissions, the 6th gear is a very tall Over drive gear.

Like in the LS1 Fbody's and Vette's the T56 six-speed, they use 5th gear for top end runs and 6th gear for cruising. It's a bit too tall of a gear for 'racing'... mainly just an economy gear.

I liked having the six-speed in the Z28, of course it had gobs of down low torque so you could just idle around in just about any gear around town.

T56
1st: 2.66
2nd: 1.78
3rd: 1.30
4th: 1.00
5th: 0.74
6th: 0.50

As you can see, 4th gear is 1:1 (drive), 5th is 25% lower and 6th gear is a 50% lower ratio. A pretty steep drop in gearing... if it was ment for 'racing' use, it'd be roughly .65 or 35% less.

If you look at the 6th gear ratio of most of the cars you mentioned, you might notice this trend, that it's strictly for highway use to help meet ever stricter milege requirements. Hell, everybody knows that the only way the LS1/LS6/LS2/LS7 manual cars can get past the gas guzzler tax is to have in the CAGS (Computer Aided Gear Select) where if you're under half throttle in 1st gear you get forced to go directly into 4th gear. Such a pain in the ass, luckily my Z28 had the CAGS eliminator already installed when I bought it.