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SlickHolden said:First D i go forIf I'm on the freeway and want to unlock the converter for overtaking i just drop it to the 2nd D for smooth faster overtaking.
pandaman said:Look man, I dont wanna have a go at anyone personally really, more the driver education/assessment scheme, but people with drivers licenses who make comments like these really worry me. I'm gonna do a bit of a long explanation here, if you already know this stuff then good, if not then it's kinda important to get the hang of it.
An automatic gearbox shares the same purpose as a manual, to provide a set of increasing ratios to allow a vehicle to accelerate easily from a standing start with short (low gears) ratios and cruise easily at high speeds with tall (high gears) ratios. This idea works due to a concept called mechanical advantage, a form of leverage. Basically the low gears give the engine more leverage on the rear wheels allowing faster acceleration, but a lower top speed than higher gears.
The automatic gearbox in your VN has 4 forward ratio's.
1st: 3.06:1
2nd: 1.63:1
3rd(white D): 1.00:1
4th(blue D): 0.70:1
What this means is that in first, for every turn of the input shaft of the gearbox the output shaft will turn 3.06 times. So the engine spins fast and the wheels turn slowly. In fourth the input shaft spins once, the output shaft spins 0.7 times, so if the engine is spinning at the same speed as it was for the first gear example, the wheels will be spinning much faster. Now in fourth the engine has much less leverage on the wheels than it did in first, so acceleration is slower.
Now in answer to your questions, in third (white D) the engine spins faster than it would at the same speed in fourth (blue D) so it is noisier, it revs and accelerates harder because there is better leverage. Now you'd think it'd use more fuel that way yeah? Well in some cases yes, but if you're puttering around town at 60km/h it may make no difference to fuel economy whether you're in third or fourth. There are a couple of reasons for this. At those kind of speeds the torque converter is unlocked, so third and fourth are effectively similar ratios, and also in the higer gear the engine may be labouring more and not working as efficiently as it would at slightly higher rev's. As mentioned by a couple of people, leaving it in third(white D) around town also causes less wear on the gearbox because it changes less often. I'll admit that I actually tend to manually shift the auto like a fully sick hectic brocuz because I like a bit more noise than what ya get just cruising around letting the box do it's own thing. It's probably bad for it, but if it breaks I'll just replace the bugger, God gave me two strong arms and half a brain for a reason.
Hokay, now fourth(blue D) is overdrive, the definition of an overdriven gear is where the output shaft is spinning faster than the input shaft, therefore fourth is the only overdriven ratio in the box.
If I'm being patronising and telling you stuff you already know, feel free to tell me to **** off, but a fair few of these threads have been popping up and I wanted to clear it up once and for all. If I've been helpful feel free to tell me to **** off anyway (everyone else does
R Photon said:
