Re: Overdrive switch ?
This site is dedicated to the Toyota Granvia, a luxury four-door people carrier (MPV) available in the UK as a grey market import from Japan. If you have general or mechanical questions about your Toyota Granvia, this is the place for you.
jarmmo wrote:It is illegal to freewheel in the UK as this will affect things like power steering and brake servo vacuum....
72degrees wrote:I assume it's also a good idea to flick the overdrive off and unlock the torque convertor if faced with a long, steep, downhill stretch (particularly if signed with an "engage low gear now" warning).
ibex32 wrote:3) I can't control the torque converter.
Richard wrote:72degrees wrote:I assume it's also a good idea to flick the overdrive off and unlock the torque convertor if faced with a long, steep, downhill stretch (particularly if signed with an "engage low gear now" warning).
Toyota have created some confusion over labelling this button as "overdrive". Yes, technically it is an overdrive in that the ratio is less than 1:1, but it's simpler to just think of it as "top gear" or "4th" gear**. By switching "Overdrive Off", you prevent the gearbox from engaging top (4th) gear, so you'll do most of your driving in 3rd gear! I've been driving my Granvia for 11 years now and I've never seen a need to switch "overdrive" off - just let the automatic gearbox do its business. Only if you're pulling a very heavy load can I think that restricting the gearbox to the lowest three gears would make any sense.
You can get engine braking only in 1st and 2nd gear, so you have to move the gear lever. The freewheel function, which precludes any engine braking, will operate in 3rd gear too.
** Technical note: In the traditional design of automobile gearboxes, "top" gear is a direct drive - the output shaft is rotating at the same speed of the input shaft with a 1:1 gear ratio. In direct drive, the gearbox runs quietest, with least energy loss and least wear; since a car spends most driving time in top gear, that's the one which usually has direct drive. The traditional "overdrive" was usually an *extra* bolted-on gearbox for luxury or sports cars, which allowed lower engine revolutions at high speeds. For some reason, Toyota designed the gearbox for the Granvia to use direct drive for third gear, not top (4th) gear. (Perhaps Toyota found that it was cheaper to modify a three-speed gearbox just by adding another set of gears and layshafts for the 4th gear.)
72degrees wrote:Sometimes the short stretches of two lanes are the only way to get past the cars and caravans going even slower (than 50 mph).
Richard wrote:72degrees wrote:Sometimes the short stretches of two lanes are the only way to get past the cars and caravans going even slower (than 50 mph).
While towing a trailer on narrow hilly sections in rural Devon? I can understand why you would find the overdrive/3rd-gear button useful and it shows how radically different are our driving styles - I'm the guy you're trying to overtake!