I read the 'stickied' topic above where the writer compared the Sport AT vs. MT (nice post!) and he showed a comparision of the 2 car's RPM's at certain speeds...

Manual at 60 mph: 2900 RPM
Manual at 70 mph: 3500 RPM
Manual at 80 mph: 3900 RPM

Auto at 60 mph: 2300 RPM
Auto at 70 mph: 2600 RPM
Auto at 80 mph: 2900 RPM

Clearly the two trannys have different gear ratios, so if the Sport AT max rpm in third makes you shift into 4th at 55-59 mph, that will really hurt its 0-60 time. So maybe the classic 0-60 test is slanted toward the MT, and maybe a 0-55 or 0-70 test would bring the paddle AT times back within a few tenths of the MT.

Note: I only have 300 miles on my Red Sport AT, so I can't test this yet, and if any Sport AT drivers have gone to redline in each gear maybe they can enlighten us.

Also: If this topic has been covered, I apologize and should be immediately banned!

 

yeah, that and the fact the auto transmissions are not a direct mechanical linkage to the transmission in the same way that a manual is. the increased complexity, friction, and weight all contribute as well. in a car with only 110hp, these things matter more than a 300hp car

 

after rereading your post, i just wanted to correct something...

if you are driving for a fast 0-60 time, it is VERY unlikely that the car will shift into 4th gear before you hit 60mph, hell, it shouldnt be in 4th before 70 either

having almost no knowledge of the exact gear ratios(dont have my car yet), i dont know for sure whether you hit 60mph in 2nd or 3rd gear though, maybe someone can clarify

 

Yeah, I don't know if the upshift to 3rd or 4th or 2nd to 3rd would interfere with the 0-60 test so I guessed... your probably right.

I've also heard about Automatics being a drag etc... maybe only should account for a few tenths? The owners manual mentions the in 'S' mode its a sequential shifter which I would think would not be viscous coupling, especially since you can use engine compression to slow the car down as you let off (in 'regular' AT's the RPMS would drop to idle as the engine freewheels)

Another issue may be shift times... my paddle equipped Sport At seems to upshift fairly quickly and while I know there are many race car driver wannabees who probably THINK they can manipulate a MT gear-shifter and clutch faster, the FASTEST MT shift technique would probably be to CRASH the gearbox, ie... don't use the clutch to yield the best acceleration times. It may work, but I wouldn't want to do it often.

 

Regardless of gear ratios, the MT will have the advantage off the line due to the ability to launch at optimum rpms.

 

NeverNZ is right on the money - the extra weight!

 

In this car, you probably don't want to take it to 70 in 3rd gear.

 

i hate to be a magazine racer, but this is likely, according to Car and Driver's test results. In their test the MT is a lot faster to 60mph than the AT, but the gap narrows in the 1/4 mile. Although the MT does trap a little higher

EDIT: forgive my lack of conviction in my answers, as i have little experience with these cars so far, i have not taken delivery of my car yet

 

The shorter gearing of the manual means that it is the one that may have an extra shift before 60 - not the automatic.

 

To Creepin, The launch of the FiT manual plus the proper shift (using the clutch), performed by someone who races and knows thier vehicle well, can outperform the FiT auto paddle shift any day!

NOW with that said, IF you vehicle is a FULL OUT RACE CAR (Not a FIt engine and transmission) more like a chevy big block with a sports torque converter and quick shift auto trans. then you will have quicker shifts than HUMAN can do ( i.e. any manual can do).

BUT as we are all FIT owners and with STOCK engine's/Transmissions FROM HONDA! The quickest and best bet is always going to be the Manualk Transmission from the factory!

SO i'm not saying that MANUALS are the fastest around necessarily, you see!

It just happens to be the case with what 99% of cars in the US! (with the exemption being the full out drag racing cars!)

 

OK, your right, and assuming gettinafit is also correct and he's a faster shifter than the paddles (although clearly he's biased and OWNS a MT ) if the shift from 2nd to 3rd in the AT DOES occur between 56 and 59mph, then in a 0-55 drag race the AT would have one less shift and maybe the difference would not be the nearly 2 seconds C&D quotes. (OK, I know my theory is a stretch throw me a bone here! )

 

I'm just stating facts, i'm not being one way or the other!

well it's about gear ratios that keep the engine in it's greatest power band!

M/T and A/T have different gear ratios to boot! So a smooth (aka slow) shifting A/T from the factory, vs. the quickest shift (harsh but faster) Helps!

someone else mentioned weight reason, that is small factor. The A/T weighs more than the M/T cause the tranny has more to it! Torque converter, clutches and drums and bands, solinoids, valve bodies, and then the regular shafts and differential (final drive gear is different ratio too). The M/T just has two shafts, with gears and synchros, a shift fork, a slave cylinder, and differential.

Sorry for the long description, may not interest anyone, but that is the reason for the weight, the A/T just has more stuff in it to do it Automatically!

Reasonable no?

 

oh yeah, it doesn't take two seconds to shift!!!! Maybe if you are trying to drive as apposed to race!

Driving you want to rev match to put less stress on the clutch and the crankshaft. hence you give is 0.5 of a second of rpm drop between shifts and engagements of clutch again. BUT if you are RACING! you will ingage the clutch and shift at the same time extremely quickly and fly off the clutch throwing the torque of the engine at 6500 rpms into the next gear ratio about 800-1200 rpms lower, causing a surge(a positive accelration surge) sometimes leading to wheel slippage (chirp).

that is why an Automatic is designed the way it is, IF every manual trans driver Shifts the way i described the WHOLE TIME they own their car, EVERY SINGLE SHIFT, then they will wear out their clutch REAL FAST, Hurt the Trans, and even Explode the Case!! Especially if you have a performance clutch with non-sprung hub and high pressure plate!

Honda will NOT design an Auto trans that will allow the driver to self destruct it! It is assumed with a Manual that you know how to drive and that the possibilites of engine/trans destruction lies in your hands!

Phew! long breathed! But i hope this helps!

 

Auto trannys take more power from the engine just to operate than manual transmissions do, so likely the auto is getting a little less power to the wheels. Also shifting is not as direct with an automatic as with a standard.

 

FRAY ADJACENT : most simply put! Good Job! Mines was too technical!

But that's it in a nut shell, the Auto takes power from engine to work, and the manual uses a lot less! (build up fluid pressures, torque converter clutch not at 100% = less power at that moment!)

 

When comparing 0 - 60 times, the mechanism of energy transfer is probably the deciding factor between a MT and an AT.

Automatic transmissions indirectly transfer energy to the wheels via a torque converter, which is filled with a fluid that is spun by the engine, which then spins a turbine that connects to the driveshaft. It's like putting your straw in your drink and stirring the fluid inside the cup. The fluid will only catch up to the speed of the straw after a while (but will never match the speed of the straw if the straw stays at a constant speed). During this time, energy is lost, caused by the friction between the straw and the fluid, and also the fluid against the interior of the cup. This is why AT accelerates slower than MT.

In manual transmission, energy from the engine is transferred directly to the driveshaft via the clutch and the gearbox, hence the torque being transferred to the wheel is more complete and the car is able to accelerate better. But this is also why when coming to a stop MT cars should shift into neutral to cut the engine off from the drivetrain, otherwise, there will be load on the engine and would cause unnecessary stress to the drivetrain and the engine.

When comparing the speed of shifting gears between AT and MT, I believe the AT is faster when you are shifting within the right parameters. AT shifting will automatically match the engine rpm and thus is forced to experience a delay unless the rpm is ideal. In the AT Fit, 3000 rpm seems to be the sweet spot for shifting, and the AT shifts seamlessly at this juncture.

The normal shifting of MT begins when you disengage the clutch and ends when you re-engage it. I'm not an MT driver, but it seems like you'll need some really quick foot + arm action to complete a faster shift than the AT. Also, Fit's MT uses synchronizers to shift between gears, these synchronizers will match the rotational speed of the gear to the engine shaft, and thus will also experience a slight delay until the gear spins up to speed.

Here's another interesting tidbit from Wikipedia for those MT drivers not driving a race car:
Also, it's not the one that uses less gears to reach 60 mph will be the faster car, it's the one whose gear ratio allows it to stay in the powerband of the engine longer while shifting through the gears that usually wins the acceleration race.

 

A synchronizer matches the speed of the faster moving gear with the next gear which is moving slower due to size of the gear (Hence ratio). Synchros prevent grinding of the gears. When your gears start grinding between shifts, most probably cause is the synchros wiped out!

As for this statement, you know the turbine that you were taling about within the torque converter, between gear changes in an automatic, the TCC (torque converter clutch) is not at 100% due to the spinning action lessened by the gear ratio, and it has to mate the engine and trans speed before 100% is achieved. ALSO, Automatic transmissions' gears are applied via fluid pressure (which i see that you know) BUT did you know that the fluid pressure that applies either holding clutches or applying clutches to make gear changes. with two fluid activated things happening at the same time (fluid actuating being smoother "i.e. slower") How do you expect to rely on what you think feels like a nice quick shift as being as defined of a shift as a in and out of a clutch?

Listen to a Professional, DON'T Your beliefs are wrong!

 

Wikipedia is describing what a synchro does, but if you have never taken apart a manual transmission to see how it works, then you do not understand correctly what they are referring to. What a synchro does is prevent gears from grinding when shifting a gear in motion with a gear in less motion due to it's size (Hence gear ratio).

You obviously don't know how an A/T works internally, I guess you haven't ripped one of these apart either. Well applied clutches or holding clutches are activated by fluid directed by the valve body actuated by solinoids (electrical signal operated). Just the combo of 2 bands holding a drumactuated by fluid pressure is a Soft event (i.e. smooth "slow") ALSO when you think you are in gear at that "moment" you are still waiting for the TCC (torque converter Clutch) to reach 100% holding capacity (which you can't feel) That is what matches engine speed with trans shaft speed.

ALL of these factors make the auto. trans slower in shifting! Much so than clutch moving in and out! Its mechanical clutch release fork on the pressure plate.

""your quote""
""Also, it's not the one that uses less gears to reach 60 mph will be the faster car, it's the one whose gear ratio allows it to stay in the powerband of the engine longer while shifting through the gears that usually wins the acceleration race"" "Your quote"

This is correct. But the Manual trans gear ratio is geared better to keep it in the power band by the way!!

 

That I understand. But doesn't this cause some sort of delay when matching the gear's speed? If so, then you're saying that MT still shifts faster with this slight delay because AT shifting procedure is entirely fluid actuated which causes even more delay to the shifting? I'm not doubting you, just trying to confirm I understand this correctly.

That's what I think as well, thanks for confirming. It (Fit MT) has a tighter gear ratios which makes the rpm drop less dramatically when upshifting, hence, should be able to keep the engine rpms near the powerband's peak (around 4.5k - 6k, if I remember correctly) when upshifting.

BTW, gettinafit, thanks for taking your time to explain the technical details, I guess I just had to force ya eh? I didn't know that you're an auto mechanic (since you referred to yourself as professional), but now I know I can really trust your words.

All my halfed-ass knowledge about transmissions are mainly gathered from howstuffworks.com, so without actually risking killing my car's transmission, I tried to understand things via articles and diagrams. Actually on the AT part, I only read the article about torque converters, so that's why I'm so ignorant about the actual shifting mechanism of ATs, and can only use words like "I believe...".

How much do you know about sequential shifting transmissions? Are they really expense to make? IMHO, I'm surprised to see that they are not yet popular among MT cars. It "sounds" to me that a MT without having to deal with manual operation of the clutch is a winner, since the shifting procedure is simplified. I know motorcycles uses sequential shifting, why aren't there more cars using this type of MT?

 

No problem, I'm not screaming, Just edumacatin!