Shifting takes time, Auto (in MM) Takes no time.

Auto is 100 pounds lighter, and is always in gear.


Just read the title, thats the real question at hand.

 

Among other things the biggest reasons are:

-Fewer gears.
-Torque converter is less effecient than a direct connection between engine and transmission as in a manual.

Look up automatic transmissions on howthingswork.com and you will should understand why.

 

A street MT vs. a street AT will be better cuz there's less drive friction and power losses. Plus, when an AT shifts, a set clutch bands inside release at the same time another set engages. During this time, the bands will momentarily work against each other and rob power from the engine. Also, an MT will let you choose your launch RPM so you can get the vehicle moving out faster. An AT cannot let you do this.

Now if you modify a street AT so that it shifts faster and include a higher stall converter, then you minimize this power loss and it then becomes better at the drags since you can launch the car at a higher rpm.

So from the factory, because of the way ATs are designed, they are at a disadvantage at the drags. But put some race components into an AT and it will become better than any MT.

But then you get into those clutchless drag only semi-manual trannys. Now those are the ultimate in high performance.

 

100lbs lighter? im pretty sure its 300lbs heavier

 

FYI 05 6MT is 26lbs heavier than 05 5AT. Gotta be the drive shaft that makes us heavier

 

i dunno bout the MM taking no time, when i drive my dad 5AT in MM it seems to take forever when compared to my 6MT.

 

It isn't about friction and power losses as much as it is about us 1)not being able to control the launch engine speed, 2) having one fewer gear, and 3) (in part due to #2) less aggressive gear ratios.

The additional driveline loss due to the AT transmission is almost entirely due ot the loss in the TC. The higher the stall speed, the poorer the coupling efficiency of the TC, which, however, yields a greater STR (torque multiplication, by virtue of of the engine RPM and hence the TC turbine spinning faster than the impeller - the AT side that is connected to the rest of the drivetrain/wheels) and stall speed.

 

IS the 5at faster in AUTO MODE or MANUAL MODE?

 

There's a huge upshift lag in MM, huge as in "oh wait, did it shift at all". That was my first reaction when I drove a 5at. The main advantage of manual mode over drive is that you can take each gear to redline, it doesn't shift any faster. So both statements you started with are a bit off.

 

It's faster in MM mode. One reason is because the car does not chose the optimum RPM to shift in first gear at WOT in D.

at WOT it takes less time to shift. If you install grounding kit, it improves a bit. Once you get the timing down you can shift at the optimum RPM's most of the time.

 

You can't launch in AT. I thought you could put it in N, rev up then throw it down to drive?

I get it about the friction tho that makes sence

 

Very, very, wrong. For the '04's its about 100 pounds heavier or so. Forget real numbers.

 

so in the 5AT to get the fastest times its best in MM mode and you switch gears right before redline right?

 

A Nutral drop is the quickest way to ruin your AT transmission.


lightforce, you are correct

 

Really? I always thought straight up "D" would be faster in a straight line, since the Manumatic mode has a slight delay in shifts.

JTrain, I hope you dont actually do that.

By the time you have to take your foot off the gas, engage the clutch, and switch the gear its pretty unlikely that you would be able to shift faster than a machine doing it almost instantly. If you take your foot off the gas in MM before shifting, yes it will take longer, but you aren't supposed to do that. But "D" does shift faster than "MM" it seems.