hi all, i'm not new..but alwiz a reader onli, never respon before.
ok shark, earlier explanations are all correct, no doubt. but if u still blur, this is the easiest way to understand.
whenever u r driving an auto car with OD, imagine u r driving a car with 4 speed manual gearbox. when u switch off the overdrive in ur auto car, its the same as u r driving in 3rd gear (manual). better acceleration but higher fuel consumption, not to mention NVH.
consumers used to complaint when ever they are in OD mode, car has poor acceleration. thus, manufacturer came up with 'power' switch. the secret is to hold any ratios (depending on speed) at a longer interval dan higher rpm. modern cars nowadays has transmission ECU which adapts to whether the driver prefers sports/hold mode or normal.
overdrive means the ratio is lower than 1. pls refer to any car magazine test drive spec or ur car owner's manual and u can see that normally for 5 speed manual, the 5th gear is an overdrive. for 6 speed manual gearbox, usually, 5th and 6th gear are both overdrive. unless, the engine has low power output like UK spec corolla EE111 (shape like corolla hatchback WRC 1999 but only 1.3 with 6 speed), if i'm not mistaken only the 6th gear is overdrive where the first 5 are closed ratios for acceleration.
fyi, CF1 waja and CM1 gen.2 has no OD switch but the 4th gear is actually an overdrive. same goes to most honda cars with auto trany. on the other hand, CF2 waja has OD switch at the lever just like E55/E54 perdana and C98/99 wira. why must use button instead if its all same u may ask? i believe its juz a perspective of design where to switch off OD is faster and easier compare to shifting the lever itself.
poor saga, iswara and wira 1.5 auto had to make do with 3 speed auto transmission. they make driving in city painless nevertheless but has really poor fuel economy. this is a complete opposite with lancer 1.5 with 4G91 where it utilised modern 4 speed gearbox.
p/s sori membebel, cant help it. overdrive is just a ratio.
