ardasaliah Posted September 18, 2006 Share Posted September 18, 2006 : So Sorry to start this off but reading around the subject sooooo many people think the OD button is a magical switch that holds the revs longer/ make it go faster/ spreads 3 gears over the rev range. Increases the 0-60 times - etc etc- the list goes on and on and on. All it does is switch off 4 gear---- Thats it very very very simple. Its not hard to work out. Sorry to rant but every so often this comes up and I am very worried/intrigued that "knowledgeable enthusiast" find the concept of OD off complicated :rolleyes Quote Link to comment Share on other sites More sharing options...
Max Headroom Posted September 18, 2006 Share Posted September 18, 2006 You forgot you need OD to go over 120mph Quote Link to comment Share on other sites More sharing options...
CardiffSupra Posted September 18, 2006 Share Posted September 18, 2006 Fair enough. But would'nt taking the car through the gears using higher revs = Turbo2 staying on = Quicker car? Im not arguing or know much about it. Just a thourght Quote Link to comment Share on other sites More sharing options...
Ian C Posted September 18, 2006 Share Posted September 18, 2006 Fair enough. But would'nt taking the car through the gears using higher revs = Turbo2 staying on = Quicker car? Im not arguing or know much about it. Just a thourght All it does is switch off 4 gear---- Thats it very very very simple. -Ian Quote Link to comment Share on other sites More sharing options...
ivan Posted September 18, 2006 Share Posted September 18, 2006 Is that the button on the gear knob everyone keeps asking about? I keep wondering about that 'cos I don't have one. Am I missing something? (Sorry, couldn't resist.) Quote Link to comment Share on other sites More sharing options...
Need4Speed Posted September 18, 2006 Share Posted September 18, 2006 All it does is switch off 4 gear---- Thats it very very very simple. Exactly! Why do they call it overdrive - it's not an MGB:blink: Quote Link to comment Share on other sites More sharing options...
Marco Posted September 18, 2006 Share Posted September 18, 2006 Why would you turn of 4th gear? ...I'm one of those that doesn't understand the OD! Quote Link to comment Share on other sites More sharing options...
DannyW Posted September 18, 2006 Share Posted September 18, 2006 Why would you turn of 4th gear? ...I'm one of those that doesn't understand the OD! if you are following a car around 55-60mph and you want to overtake, you can flick the o/d off to drop you down to 3rd before you pull out and accelerate (sp?) past the car, just like you would in a manual car. Otherwise, if you rely on kickdown then you're normally halfway over the wrong side of the road when the box drops a cog. Quote Link to comment Share on other sites More sharing options...
mathew Posted September 18, 2006 Share Posted September 18, 2006 when i was a newbie i didnt know what it was for and im not ashamed to admit that having never been in an auto. only the other week did i then realise that i had driven all the way from london to llanelli, after picking it up,with it off and was wondering why it wouldnt go above 120 mph lol:d Quote Link to comment Share on other sites More sharing options...
AJI Posted September 18, 2006 Share Posted September 18, 2006 just buy a manual .. its a lot easier Quote Link to comment Share on other sites More sharing options...
mathew Posted September 18, 2006 Share Posted September 18, 2006 speaking of manual....what is the MANU button for??? Quote Link to comment Share on other sites More sharing options...
Matt H Posted September 18, 2006 Share Posted September 18, 2006 : So Sorry to start this off but reading around the subject sooooo many people think the OD button is a magical switch that holds the revs longer/ make it go faster/ spreads 3 gears over the rev range. Increases the 0-60 times - etc etc- the list goes on and on and on. All it does is switch off 4 gear---- Thats it very very very simple. Its not hard to work out. Sorry to rant but every so often this comes up and I am very worried/intrigued that "knowledgeable enthusiast" find the concept of OD off complicated :rolleyes Rant justified mate! its cos people dont understand a gear box! Quote Link to comment Share on other sites More sharing options...
carl0s Posted September 18, 2006 Share Posted September 18, 2006 Exactly! Why do they call it overdrive - it's not an MGB:blink: It's called overdrive because it's an overdrive gear, just like 6th in a 6spd manual and 5th in a 5spd. Don't ask me why they don't call 5th/6th 'overdrive' Quote Link to comment Share on other sites More sharing options...
Pixelfill Posted September 18, 2006 Share Posted September 18, 2006 Exactly! Why do they call it overdrive - it's not an MGB:blink: Overdrive can refer to two different things. An overdrive is a device which was commonly used on rear-wheel drive automobiles to allow the choice of an extra-high overall gear ratio for high speed cruising, thus saving fuel, at the cost of less torque. It also refers to a combination of gearing inside a transmission or transaxle which results in the output speed being greater than the input speed. In the latter case, "overdrive" does not refer to a physically separate identifiable part/assembly. ... The automatic transmission automatically shifts from OD to 3rd gear when more load is present. When less load is present, it shifts back to OD. Under certain conditions, e.g: driving uphill or towing a trailer, the transmission may "hunt" between OD and 3rd gear, shifting back and forth. In this case, switching it off can help the transmission to 'decide'. It may also be advantageous to switch it off if engine braking is desired, for example, driving downhill. For more details, check your owner's manual http://en.wikipedia.org/wiki/Overdrive_%28mechanics%29 Mike Quote Link to comment Share on other sites More sharing options...
carl0s Posted September 18, 2006 Share Posted September 18, 2006 Good find that Mike. In our case, it's not a specific 'overdrive assembly'. Such a device would give a total of six effective gear ratios if we had one. As I understand it anyway. In our case it's just that it's an overdriven gear - the output speed is greater than the input speed. Quote Link to comment Share on other sites More sharing options...
Pixelfill Posted September 18, 2006 Share Posted September 18, 2006 That was my understanding too Mike Quote Link to comment Share on other sites More sharing options...
Digsy Posted September 18, 2006 Share Posted September 18, 2006 Does it not also defeat the lock-up clutch on the torque converter? When I turn OD on, I feel like get a slight increase in speed, which you get if the lock-up clutch made the speeds of the gearbox input shaft equal to the engine speed. With OD off I get a slight drop in speed, ike the gearbox is spinning slower, but not a whole gear's worth slower. If you get my drift. Quote Link to comment Share on other sites More sharing options...
carl0s Posted September 18, 2006 Share Posted September 18, 2006 Does it not also defeat the lock-up clutch on the torque converter? When I turn OD on, I feel like get a slight increase in speed, which you get if the lock-up clutch made the speeds of the gearbox input shaft equal to the engine speed. With OD off I get a slight drop in speed, ike the gearbox is spinning slower, but not a whole gear's worth slower. If you get my drift. I get a similar thing with MANU. Revs rise very slightly when MANU is engaged. Quote Link to comment Share on other sites More sharing options...
Guest ozsupra Posted September 20, 2006 Share Posted September 20, 2006 Q. I have just bought an Auto MKIV. What are the three buttons for? A. 1. Overdrive. Engages the fourth gear on the auto box. Actually reduces the pressure with the gearbox so that the RPMs fall and fuel economy is increased. 2. Has two Japanese letters next to button. Roughly translated these mean "Park Release". If the button is pressed the gear stick can be moved (at the same time) from the park position without depressing the brake pedal. 3. Has the word "MANU" on the button. Allows the driver to select "Power" or "Economy" mode. The only difference is in power mode the car will hold the first and second gears longer (to higher revs) and allow you to take off faster at the lights. Power mode will increase your fuel consumption. Quote Link to comment Share on other sites More sharing options...
Need4Speed Posted September 20, 2006 Share Posted September 20, 2006 The fundamental reason for the manual overide (MANU) is to hold a particular gear. Primarily this is to allow you to pull away in 2nd etc. on slipery (such as snow or grass) surfaces. It's not fundamentally there so you can go drag racing. Quote Link to comment Share on other sites More sharing options...
Soop Dogg Posted September 20, 2006 Share Posted September 20, 2006 3. Has the word "MANU" on the button. Allows the driver to select "Power" or "Economy" mode. The only difference is in power mode the car will hold the first and second gears longer (to higher revs) and allow you to take off faster at the lights. Power mode will increase your fuel consumption. Sorry, but this is incorrect. There is no "Power" or "Economy" mode. The MANU button does make the transition between gears faster. The ETCS (throttle control) backs the throttle off between gear changes when under load. (Like at WOT) This is to make the gear change smoother. In MANU mode, this 'backing off' of the throttle is reduced. This can mean slightly harsher changes but faster. As for MANU mode holding on to the gear to higher revs, this will be because it won't change up until you move the gear lever!!! AND.....as for getting off faster at the lights in MANU mode, as stated by Need4Speed, if you've got it in anything other than 1st, you'll pull away in 2nd.....which ain't that fast. Try it and see. Quote Link to comment Share on other sites More sharing options...
Ian C Posted September 20, 2006 Share Posted September 20, 2006 Q. I have just bought an Auto MKIV. What are the three buttons for? A. 1. Overdrive. Engages the fourth gear on the auto box. Actually reduces the pressure with the gearbox so that the RPMs fall and fuel economy is increased. 2. Has two Japanese letters next to button. Roughly translated these mean "Park Release". If the button is pressed the gear stick can be moved (at the same time) from the park position without depressing the brake pedal. 3. Has the word "MANU" on the button. Allows the driver to select "Power" or "Economy" mode. The only difference is in power mode the car will hold the first and second gears longer (to higher revs) and allow you to take off faster at the lights. Power mode will increase your fuel consumption. Well, one out of three isn't bad. Where did you get that FAQ from? 1 - The gearbox pressures I thought were entirely mechanical. And anyway, reducing pressures wouldn't make the revs fall OD just stops you from going into 4th gear. 3 - MANU sticks you in a gear and leaves you there. You never go into 1st unless you select 1st, so it's not going to help you get away from the lights any faster. There is no power or economy mode, it's manual or automatic. The "holding the revs" thing is such an urban myth, especially as MANU mode you'll not change up until you tell it to anyway. The autobox will wind up to the redline if your foot is on the floor no matter what mode it's in - that's why it's an "auto" - no manual intervention required. I feel an FAQ entry coming on... -Ian Quote Link to comment Share on other sites More sharing options...
Guest Garfy Posted September 20, 2006 Share Posted September 20, 2006 hehehe, I love these threads. 1) Overdrive is 4th gear, thats it pure and simple 2) MANU is manual control (with faster gear changes), thats it pure and simple the only question I have is does anyone know why it won't let you use overdrive in MANU mode? Quote Link to comment Share on other sites More sharing options...
Thorin Posted September 20, 2006 Share Posted September 20, 2006 Press all three buttons (OD, MANU, Red) at once three times and you enable extra special super turbo mode! Quote Link to comment Share on other sites More sharing options...
Guest Garfy Posted September 20, 2006 Share Posted September 20, 2006 Press all three buttons (OD, MANU, Red) at once three times and you enable extra special super turbo mode! :rlol: Quote Link to comment Share on other sites More sharing options...
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