difference ng 4 speed automatic against 5 speed manual transmission

**xenix** · June 21st, 2007 11:48 AM

Out of curiosity lang, parehas ba ang gearing ng automatic and manual transmissions considering na 4 speed ang automatic at 5 speed ang manual? bakit hindi na lang silang parehong 5 speed?

**alwayz_yummy** · June 21st, 2007 11:53 AM

nope hindi, maaring iba ang ratio ng matic sa manual. pero di naman nagkakalayo...

mas maraming gears ang matic than manual in reality, masyadong packed,e...

or just a marketing hype na din..

**OTEP** · June 22nd, 2007 12:08 AM

The ratios are different. Iba ang spread ng ratios ng 4A/T sa 5M/T to account for the lesser available gear selections. The axle ratio can be different also.

There was a time when 4 speed a/t's were considered the 'norm' in the industry just like the olden times when a 3 speed manual came standard with cars.

Nowadays, production costs and packaging constraints dictate the number of speeds in a transmission.

**orly_andico** · June 22nd, 2007 12:30 AM

a conventional manual transmission uses a sliding gearbox. an automatic uses a double planetary gearset. more expensive.

that's why automatics used to have 4-speeds and most still do; only the newest and higher-end cars have 5-speed automatics.

the automatic also doesn't need a short first gear because it has a torque converter, which increases the torque. so the 1st gear on an automatic is kind of equivalent to 2nd gear on a 5MT.

the 4th gear on a 5MT is the 1:1 ratio gear. the 3rd gear on a 4AT has the same function.

although i must admit, the viscous coupling torque converter and the longer gearing of the AT means driving it is a bore. unless it's a Ford SUV or Merc AMG with gobs of torque.... never driven one of those.

**OTEP** · June 22nd, 2007 12:35 AM

Newer Lexus sedans already claim to have 8 speeds. I just don't know if this is via conventional gears or via CVT (which is cheating because CVT technically have an infinite number of gears between low and high

).

**rion** · June 22nd, 2007 01:14 AM

automatic being slow because it only has 4 speed is not true. many people thinks like this...

however, automatic is slower and feels soft because it runs on pressure hydraulics...

though I encountered some few a/t that feels fast and you feel a strong drag. but the actual acceleration is still in question...

with continuously variable transmission (CVT), no idea why they have 7 speeds. Honda hatch ek9 and City.
probably 7 speed doesn't mean 7 gears?

and why this old technology was never succesful over hydraulics.

**alwayz_yummy** · June 22nd, 2007 07:29 AM

cvt ata is stil in the development stage... di nga dumating dito yung mga HRV na CVT, mga hyper-cvt ng nissan for the low-displacement engines

**orly_andico** · June 22nd, 2007 08:42 AM

Originally Posted by rion

automatic being slow because it only has 4 speed is not true. many people thinks like this...

however, automatic is slower and feels soft because it runs on pressure hydraulics....

No, no.. automatics are generally slower than manuals with the same car and engine because...

1) the automatic usually has 4 speeds, so the gears are taller, meaning the engine has to produce torque lower in the RPM powerband
2) the torque converter is a viscous coupling, unlike the clutch
3) there is more loss in an automatic than in a manual

**Camgen6** · June 22nd, 2007 09:49 AM

Originally Posted by OTEP

Newer Lexus sedans already claim to have 8 speeds. I just don't know if this is via conventional gears or via CVT (which is cheating because CVT technically have an infinite number of gears between low and high

).

Sir Otep, conventional 8 speed auto tranny yata at di CVT. Ang alam ko kasi Toyota/Lexus ay gumagamit ng CVT sa mga Hybrid nila di ko lang alam sa bagong LS600H na ilalabas nila.

**rion** · June 22nd, 2007 01:49 PM

Originally Posted by orly_andico

No, no.. automatics are generally slower than manuals with the same car and engine because...

1) the automatic usually has 4 speeds, so the gears are taller, meaning the engine has to produce torque lower in the RPM powerband
2) the torque converter is a viscous coupling, unlike the clutch
3) there is more loss in an automatic than in a manual

my point over most people thinks automatic being slow because it only has 4 speed is not true. because most people think it has the same gear size and works same like a m/t but only powered by computer.

heck most old conventional a/t don't require a computer to shift, but the tranny itself sensing the pressure load. (works like a mechanical clock where the big hand and the date moves on a certain point of the seconds and the minute hand)

the viscous coupling is also present in m/t differentials.

the difference is that viscous coupling in the a/t tranny is powered by hydraulic pressure.

it's not the clutch that make a m/t faster but the engine and tranny itself having physical contact. unlike a/t where the engine pushes it's tranny by pressure and hydraulic pressure has more power loss...

Originally Posted by alwayz_yummy

cvt ata is stil in the development stage... di nga dumating dito yung mga HRV na CVT, mga hyper-cvt ng nissan for the low-displacement engines

ngek, how come it is still in development stage where the history of cvt is already old.

they probably doubt the success of cvt and considered the cost.

[SIZE=1]No More Gears: A Timeline of CVT Innovation[/SIZE]
[SIZE=1]1490 - da Vinci sketches a stepless continuously variable transmission [/SIZE]
[SIZE=1]1886 - first toroidal CVT patent filed [/SIZE]
[SIZE=1]1935 - Adiel Dodge receives U.S. patent for toroidal CVT [/SIZE]
[SIZE=1]1939 - fully automatic transmission based on planetary gear system introduced [/SIZE]
[SIZE=1]1958 - Daf (of The Netherlands) produces a CVT in a car [/SIZE]
[SIZE=1]1989 - Subaru Justy GL is the first U.S.-sold production automobile to offer a CVT [/SIZE]
[SIZE=1]2002 - Saturn Vue with a CVT debuts; first Saturn to offer CVT technology [/SIZE]
[SIZE=1]2004 - Ford begins offering a CVT[/SIZE]

looks like same on hydro and hybrid cars. ang tagal.....