Ian C
20-09-06, 15:13
The MkIV Supra autobox is considered by many to be an excellent auto gearbox, and one of the best most have ever driven. It has an Overdrive button and a MANU (manual mode) button, and these are the source of much confusion and urban mytherry. Here below is the function of these buttons and how the autobox responds, according to years of experience of several owners
Normal Mode (Overdrive ON, MANU OFF)
Selecting L will give you 1st gear only
Selecting 2 will give you 1st and 2nd gear, with normal shift logic applied
Selecting D will give you 1st, 2nd, 3rd, and 4th gear (overdrive), with normal shift logic applied
MANU Mode (Overdrive ON, MANU ON)
Selecting L will give you 1st gear only
Selecting 2 will give you 2nd gear only
Selecting D will give you 2nd and 3rd gears only. The box will attempt to stay in 3rd most of the time, but it is possible to kickdown into 2nd if your speed is below 70-75mph. The box will also select 2nd gear if you come to a crawl/stop, and will reselect 3rd using the normal change logic, but the gear changes will be that bit quicker (see below).
Overdrive has no effect in MANU mode, you'll never get beyond 3rd gear unless you hit the redline, at which point it changes up into overdrive to protect the engine and gearbox. If you engage MANU whilst is overdrive then it will not immediately change down, but waits until there is a need to change down following normal change logic. If you are going faster than 3rd gear can deliver then it will never change down until your speed drops to something deliverable by that gear. This stands, in fact, for any manual gear selection - it won't happen unless the resultant gearchange drops the revs within the available rev range. Banging it into L at 100mph will merely result in an electronic sneer from the box. :) (Park and Reverse are different matters...)
MANU makes the transitions between gears faster. The ECTS throttle system cuts back on the throttle during gearchanges, and in MANU mode it cuts back less, therefore making the shifts harsher but losing a bit less acceleration during the gearchange.
MANU mode does not "hold the gear longer" as it holds the gear indefinitely anyway - it shifts when you make it shift. The exception is when the stick is in D, as described above - the shifting pattern will still follow normal logic, i.e. it depends on throttle position, engine load, and revs as to when it changes gear.
Overdrive Off Mode
Selecting L will give you 1st gear only
Selecting 2 will give you 1st and 2nd gear, with normal shift logic applied
Selecting D will give you 1st, 2nd, and 3rd gear, with normal shift logic applied
It will not change gear any faster and will not "stay in gear longer" just because overdrive is off. The autobox will already wind up to the redline if you are at wide open throttle, it knows you want power, that's why it's an 'auto' - you don't need manual intervention from the driver to persuade it to stay in gear.
Also of note - the gearbox may come out of MANU mode and overdrive Off mode if the gearbox is risking damage by staying in them (i.e. it's overheating).
Thanks to Mawby, Class One and Soop Dogg for their technical input to this :)
-Ian
Normal Mode (Overdrive ON, MANU OFF)
Selecting L will give you 1st gear only
Selecting 2 will give you 1st and 2nd gear, with normal shift logic applied
Selecting D will give you 1st, 2nd, 3rd, and 4th gear (overdrive), with normal shift logic applied
MANU Mode (Overdrive ON, MANU ON)
Selecting L will give you 1st gear only
Selecting 2 will give you 2nd gear only
Selecting D will give you 2nd and 3rd gears only. The box will attempt to stay in 3rd most of the time, but it is possible to kickdown into 2nd if your speed is below 70-75mph. The box will also select 2nd gear if you come to a crawl/stop, and will reselect 3rd using the normal change logic, but the gear changes will be that bit quicker (see below).
Overdrive has no effect in MANU mode, you'll never get beyond 3rd gear unless you hit the redline, at which point it changes up into overdrive to protect the engine and gearbox. If you engage MANU whilst is overdrive then it will not immediately change down, but waits until there is a need to change down following normal change logic. If you are going faster than 3rd gear can deliver then it will never change down until your speed drops to something deliverable by that gear. This stands, in fact, for any manual gear selection - it won't happen unless the resultant gearchange drops the revs within the available rev range. Banging it into L at 100mph will merely result in an electronic sneer from the box. :) (Park and Reverse are different matters...)
MANU makes the transitions between gears faster. The ECTS throttle system cuts back on the throttle during gearchanges, and in MANU mode it cuts back less, therefore making the shifts harsher but losing a bit less acceleration during the gearchange.
MANU mode does not "hold the gear longer" as it holds the gear indefinitely anyway - it shifts when you make it shift. The exception is when the stick is in D, as described above - the shifting pattern will still follow normal logic, i.e. it depends on throttle position, engine load, and revs as to when it changes gear.
Overdrive Off Mode
Selecting L will give you 1st gear only
Selecting 2 will give you 1st and 2nd gear, with normal shift logic applied
Selecting D will give you 1st, 2nd, and 3rd gear, with normal shift logic applied
It will not change gear any faster and will not "stay in gear longer" just because overdrive is off. The autobox will already wind up to the redline if you are at wide open throttle, it knows you want power, that's why it's an 'auto' - you don't need manual intervention from the driver to persuade it to stay in gear.
Also of note - the gearbox may come out of MANU mode and overdrive Off mode if the gearbox is risking damage by staying in them (i.e. it's overheating).
Thanks to Mawby, Class One and Soop Dogg for their technical input to this :)
-Ian