[fat pat]

Quote:

Originally Posted by pne /img/forum/go_quote.gif can someone explain to me exactly what auto and manual synch gearboxes are? I have a vague idea it involves matching transmission speed to engine speed but the whole process is over my head. Also, how does double clutching work? I know the procedure but what is it supposed to achieve that standard clutch manipulation can't? What is the big deal with short shifters? Is their sole purpose just to make the lever travel shorter? Why don't cars just come with short lever throws in the first place? Finally, every single manual I've driven has absolutely terrible feel at the lever. It feels like you're wobbling a stick in mud. Is there any reason why they are not more precise? This is based on a comparison to a motorcycle shift mechanism, which is smooth and accurate, with a sharp *snick* each time you change gears. In a cars shifter there is so much free play and wobble, and it doesn't help that most of the time you are wobbling around the needlessly thick cover that seemingly serves no purpose but to make the action feel even worse.

a synchro is a device that matches transmission speed to engine speed, thus eliminating the need to double clutch, it makes it so shifting is easier on the driver, and shifts can be made much faster and smoother

double clutching is when you are shifting from one gear to another, push in the clutch, release the car from the gear, disengage the clutch, so the transmission is connected to the motor in neutral, when revs fall to where they would be in the next gear, you re-engage the clutch, and put it into the next gear. this is for use on older, non-synchronized transmissions, and really has no use in modern trannies

short throw shifters change the fulcrum point of the shifter, to make shifts shorter, they also require more effort. which is why most arent included in factory shifters. most traditional stick drivers arent too woried about sporty driving, and a smoother, longer throw is easier for them.

and shifter preciceness has alot to do with the base of shifter mount, where the transmission is located(rear wheel drive cars are traditionally tighter than front wheel) and the type of transmision it is. a tighter shifter generally transmits more vibraton through the shifter to the driver, which most people will find unenjoyable. this is not always the case however, as with some mazda transmissions, and bmw transmissions.

 

[kg21]

Quote:

Originally Posted by pne /img/forum/go_quote.gif So we've got some stick drivers eh...maybe you guys can answer some of my questions. can someone explain to me exactly what auto and manual synch gearboxes are? I have a vague idea it involves matching transmission speed to engine speed but the whole process is over my head. Also, how does double clutching work? I know the procedure but what is it supposed to achieve that standard clutch manipulation can't? What is the big deal with short shifters? Is their sole purpose just to make the lever travel shorter? Why don't cars just come with short lever throws in the first place? Finally, every single manual I've driven has absolutely terrible feel at the lever. It feels like you're wobbling a stick in mud. Is there any reason why they are not more precise? This is based on a comparison to a motorcycle shift mechanism, which is smooth and accurate, with a sharp *snick* each time you change gears. In a cars shifter there is so much free play and wobble, and it doesn't help that most of the time you are wobbling around the needlessly thick cover that seemingly serves no purpose but to make the action feel even worse.

they already answered the other questions, but as to your last one you need to drive a performance car. A mediocre car will have a mediocre transmission, that goes for both types actually (unless you just hate them all no matter what). Out of affordable performance cars I have driven, the s2000, Evo, and MR Spyder all felt really good, the MRS actually felt like a bolt action rifle, just awesome. I haven't driven anything super expensive but I would guess porsche has the best feel from what I've read. Bmw used to be awesome but they've been on the decline for quite awhile in terms of "feel" both in shifter/steering/ handling etc, I'm not a fan of the newer zf units atleast for the 3 series.

 

[error401]

Quote:

Originally Posted by marvin /img/forum/go_quote.gif Slushbox. I'm a fan of using the right tool for the job. (Commuting for me.)

Believe it or not, I prefer a manual transmission for commuting. I find that it really helps me focus on the task at hand (driving). Without having to pay at least a passing mind to what the car is doing, I'd be a much more absent-minded while driving. Not to mention that it keeps me awake when I'm working these horrible 6:00am starts. Also, from my experience observing other drivers, people tend to be more aware of what's going on around them when they're driving stick, probably anticipating when they need to shift and avoid doing a clumsy job of it.

My commute's not too bad though. I'm lucky enough to avoid the parking lots; at worst I'm averaging 50Km/h with a few complete stops in the 20KM I travel on the freeway.

And of course the usual benefits once you get out of the traffic

. Even my piece of junk '94 Accord is pretty fun to drive, despite being in poor mechanical condition and probably making around 100HP on a good day.

 

[krmathis]

No car at the moment, but my last one had automatic transmission.

 

[Quaddy]

auto here, couldnt go back to manual now.

 

[chesebert]

heh..heel/toe is so addicting I do it for every corner

I think its safer to do it because I can quickly decrease my speed (breaking + engine break) going through a corner and I am in the correct gear to get me out of the corner. But really it sound pretty interesting when you come into a corner and you rev your engine up going down in gear.

 

[taylor]

five speed Maxima.

I like it because of the control I have over it. At low speeds, by being precise with the clutch, I have so much control over how fast I am going, without needing the brakes. If I needed to move six inches forward in an auto, it's a horrible thing where you let go of the brakes, the car shoots forward, and you slam on the brakes. With the five speed, I can just let off the clutch a little bit until I have forward momentum, then push it all the way down and slowly coast until I'm exactly where I want to be.

I also have more control in my acceleration, because I can downshift at will. If I am doing 40mph in 4th gear, and I need to pass someone, it's very easy for me to step on the gas, shift to third, and pull on him. Most autos will downshift if you kick hard on the gas pedal, but I prefer doing it myself. I know in my dad's slushbox Mazda, if you step hard on the gas it will downshift, rev up, but it will take a few seconds for it to start accelerating, whereas my Maxima does it instantly.

The instant throttle response is really great as well. If I hit the gas, my car pulls forward immediately. It doesn't rev up high and wait for the transmission to catch up.

I also like being able to control my shift points. For normal driving I can shift at a decently low RPM, which is bad for acceleration but good on gas. If I need to pass or something, I can shift much higher and get more acceleration.

 

[ken36]

I'm no longer a purist. Automatic.

 

[macky]

My Mazda 3 is an automatic with SportAT (Tiptronic). So I can go from the super lazy of driving an auto to having a little more control over the engine with the SportAT. My next car might just be a manual, but that's a long ways off right now...

 

[error401]

Quote:

Originally Posted by macky /img/forum/go_quote.gif My Mazda 3 is an automatic with SportAT (Tiptronic). So I can go from the super lazy of driving an auto to having a little more control over the engine with the SportAT. My next car might just be a manual, but that's a long ways off right now...

I was looking at the possibility of buying a 3 in the next couple years. How do you like it?

I think the biggest thing that bugs me about automatics is the throttle delay due to the torque converter. I once heard that Honda automatics are just a manual gearbox that's actuated automatically, but I've never driven one so I don't know that there's any stock in this claim. How's the Mazda tranny feel in this respect?

 

[ojnihs]

manual 6 speed here as well.

 

[augustwest]

manual for me -

I've always owned small engine cars and find that a manual transmission works best with those.

- augustwest

 

[zachary80]

I drive a 5spd Mazda3

Quote:

Originally Posted by chesebert /img/forum/go_quote.gif Does M5 qualify as hi-end sedan?

Aren't they all 6spd Manumatics?

 

[pne]

Quote:

Originally Posted by fat pat /img/forum/go_quote.gif double clutching is when you are shifting from one gear to another, push in the clutch, release the car from the gear, disengage the clutch, so the transmission is connected to the motor in neutral, when revs fall to where they would be in the next gear, you re-engage the clutch, and put it into the next gear. this is for use on older, non-synchronized transmissions, and really has no use in modern trannies

what I don't understand is, you are trying to drop the engine rpm to match the transmission speed correct? Once you press the clutch the engine is released from the transmission and already begins to drop rpm, what does letting it out in neutral, disengaging it, shifting up, and letting it out again achieve? Seems to me that all you need to do is clutch in, wait a fraction of a second for the rev's to drop, and shift up.

Don't even get me started on the ridiculous amount of unnecessary travel on a car's clutch pedal. If I were to design a clutch on a car it would have 5-6 inches travel max. Every time I go to hit the clutch it feels like I'm losing my balance in the seat.

 

[error401]

Quote:

Originally Posted by pne /img/forum/go_quote.gif what I don't understand is, you are trying to drop the engine rpm to match the transmission speed correct? Once you press the clutch the engine is released from the transmission and already begins to drop rpm, what does letting it out in neutral, disengaging it, shifting up, and letting it out again achieve? Seems to me that all you need to do is clutch in, wait a fraction of a second for the rev's to drop, and shift up.

The point of double clutching is that the spinning parts of the transmission have momentum. When the clutch is engaged before you start your shift, the transmission parts are spinning at the same speed as the engine. If you were to simply disengage the clutch and shift, when you reengage the clutch, the transmission will be spinning at the old engine speed, while the engine has had a chance to come up or down to the new speed. If you reengage the clutch normally, this results in a rough shift and more clutch and synchro wear as the momentum of the transmission parts is burned off as you shift.

Double clutching adds an extra step in between to synchronize the transmission with the new engine speed. Since the transmission is in neutral, you can safely engage the clutch and the transmission will spin up or down to the new speed without unbalancing the car. It has a few advantages, most significant during the downshift. First, the synchros operate by friction; they press the new gear against the main transmission shift prior to the new gear being engaged, to bring the gear to the new speed before the teeth try to engage. If the speeds are already relatively in sync, there will be less wear here. Second, the shift will be smoother since the whole drivetrain should be fairly well synchronized if you shift properly; the revs will be the right speed for the new gear at the wheel speed, and all transmission parts will be in sync with engine rpm. In old cars without synchros this was a necessary step or the gears would not mesh since they're not rotating at the same speed.

Disclaimer: I'm not a mechanical engineer and don't fully understand the forces involved, but I do it every downshift and it makes the shifts much smoother both in the lever action and the car's centre of gravity.