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Topic: overdrive (Read 1608 times) |
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rich1
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london cabbies have the knowledge!!
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settle an arguement for me , the overdrive should be used for motorway driving . yes or no? and what does it actually do for the car?
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gozz
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Re: overdrive
« Reply #1 on: Feb 28th, 2009, 9:50pm » |
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Rich.
If you mean overdrive on your Scorp it engages automatically anyway,the button on the side of the gear selector is to temporarily disengage it.On a manual box you can choose whether or not to select it.The purpose of it is of course to give better fuel economy,but a lusty engine is needed to obtain this,there would be little point in fitting overdrive to a low output engine unless the diff ratio were lowered to match.
Are yer wimme?
GOZZ.
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gost
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Re: overdrive
« Reply #2 on: Feb 28th, 2009, 10:16pm » |
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Gozz, even at this time of night you are a wealth of wisdom  As for me, to much wine, not a clue what u all talking about 
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2.3 ultima
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gozz
Senior Member
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Posts: 3475
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Re: overdrive
« Reply #3 on: Feb 28th, 2009, 10:23pm » |
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gost.
I understand me old mate,but only when a suitable noggin has been imbibed,or if you happen to be a Roman Candle,a modest libation has been taken .
In other words ' yesh oi no watcher mean ' 
GOZZ.
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big_timer
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2.3 manual ultima saloon
Posts: 183
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Re: overdrive
« Reply #4 on: Mar 1st, 2009, 12:20am » |
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overdrive on a manual?how do i engage that gozz is there a special button or something like that?
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5stud
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Re: overdrive
« Reply #5 on: Mar 1st, 2009, 12:48am » |
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overdrive brings back memoreys.mk2 vanden plas 3 speed plus overdrive big leaver you pulled from under the dash to engage .even had a distreutor on the gearbox to disengage when you sloed down .probiley last ford to use proper overdrive mk 3 trasit
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Jonnycab
Senior Member
Former owner of 2.3 Ultima Facelift saloon
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Re: overdrive
« Reply #6 on: Mar 1st, 2009, 1:48am » |
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on Feb 28th, 2009, 9:23pm, rich1 wrote:| settle an arguement for me , the overdrive should be used for motorway driving . yes or no? and what does it actually do for the car? |
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In laymans terms.....overdrive on the Scorpio auto is the forth gear ....... & as Gozz states, is for economy at high speed 
Also, as far as I'm aware, MT75 manual gearboxes don't have this option
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Simmo
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Re: overdrive
« Reply #7 on: Mar 1st, 2009, 7:45am » |
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In effect fifth gear is a form of overdrive. In 'days of yor' when JC was but a twinkle in his dads eye cars mostly had just four gears and a lack of motorways meant that high speed cruising was unusual. As both cars and roads improved cars were equipped with a switch which enabled the driver to,in effect, select a higher gear when the road conditions allowed thus lowering the engine revs and increasing economy. Snoopy, Gozz and Gost will no doubt remember such innovations !  and cars with only three gears and wipers working off a vacuum which slowed down as you went up hill!!.
Highlander.....before you reply remember us 'oldies' are watching you!!
A more detailed explanation,and history is HERE Rich.
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Scorpio_Mike
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Jeep Grand Cherokee 3.0 V6 & 2.8 Sierra XR4i 4x4
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Re: overdrive
« Reply #8 on: Mar 1st, 2009, 8:26am » |
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I remember my Sunbeam Rapier fastback - had O/D on 3rd & 4th - effectively a 6-speed gearbox - WOW 
On the Scorpio auto box, I thought they were 4-spd + O/D 
I'm sure I've counted the gearchanges going up and 4th comes in at around 40 ~ 42 mph, O/D comes in at around 50 mph.
Can someone tell me if this is right or have I imagined the extra change 
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Star sign is Scorpio !
Sierra XR4i's are great...especially when fitted with 4WD
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big_timer
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2.3 manual ultima saloon
Posts: 183
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Re: overdrive
« Reply #9 on: Mar 1st, 2009, 2:58pm » |
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glad i brought back some memories
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scorpio_man
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Ford Kuga awd
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Re: overdrive
« Reply #10 on: Mar 1st, 2009, 3:03pm » |
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on Mar 1st, 2009, 8:26am, Scorpio_Mike wrote:I remember my Sunbeam Rapier fastback - had O/D on 3rd & 4th - effectively a 6-speed gearbox - WOW
On the Scorpio auto box, I thought they were 4-spd + O/D
I'm sure I've counted the gearchanges going up and 4th comes in at around 40 ~ 42 mph, O/D comes in at around 50 mph.
Can someone tell me if this is right or have I imagined the extra change |
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hi there
what you are getting is the t/c locking up.
hth
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gozz
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Posts: 3475
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Re: overdrive
« Reply #11 on: Mar 1st, 2009, 8:04pm » |
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Yes,as Simmo says top gear in most modern manual boxes is overdriven,thus negating the need for a seperate overdrive unit that was bolted oto the back of the main box,and operated on 3rd and 4th only,having a seperate switch,which on later vehicles was in the top of the gear knob.
GOZZ.
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rich1
Full Member
london cabbies have the knowledge!!
Posts: 747
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Re: overdrive
« Reply #12 on: Mar 1st, 2009, 10:57pm » |
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so if your driving around town should you switch it off??
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Tompion
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1997 2.3 Ultima estate.
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Re: overdrive
« Reply #13 on: Mar 1st, 2009, 11:31pm » |
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With regard to driving under power I don’t think it matters, but with your foot off the throttle it gives engine braking.
With some long slight declines I commonly use, turning off overdrive is just enough to keep the speed down to 30mph without using the brakes.
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mr._floppy
Junior Member
Posts: 100
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Re: overdrive
« Reply #14 on: Mar 2nd, 2009, 2:06am » |
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In simple terms, in a 5 speed manual boxes, when you're in 4th gear the engine is turning the same speed as the propshaft .
In 5th gear the engine is turning slightly slower than the propshaft which means lower revs, higher speed and better fuel economy but less torque and less puff when you come to an incline and you have to change to 4th or 3rd.
Automatics have the same system except less gears, 4th being the Overdrive.
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Highlander
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Expert
13 Scorpios, XR4x4, Suzuki SJ413 for off road :)
Posts: 8244
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Re: overdrive
« Reply #15 on: Mar 3rd, 2009, 9:25pm » |
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on Mar 1st, 2009, 10:57pm, rich1 wrote:| so if your driving around town should you switch it off?? |
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Its just a higher gear Rich, if you press the button on the shifter and the green OD light shows on the dash then you have disabled top gear and it will only use 1st 2nd and 3rd.
I only really ever use it for maximum acceleration
switching it off at under 50mph will not make any difference.
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on Oct 17th, 2011, 12:35pm, Simmo wrote:| I give up ! Too much for an old boy! |
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and11
Junior Member
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Posts: 61
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Re: overdrive
« Reply #16 on: Mar 17th, 2009, 12:26pm » |
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on Mar 3rd, 2009, 9:25pm, Highlander wrote:
Its just a higher gear Rich, if you press the button on the shifter and the green OD light shows on the dash then you have disabled top gear and it will only use 1st 2nd and 3rd.
I only really ever use it for maximum acceleration
switching it off at under 50mph will not make any difference.
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Surely that's what the S button is for?
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mindofitsown
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Re: overdrive
« Reply #17 on: Mar 17th, 2009, 1:47pm » |
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on Mar 17th, 2009, 12:26pm, and11 wrote:
Surely that's what the S button is for? |
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Hi "and11",
Actually no, the 'S' button causes the electronics to upshift the autobox at higher speeds (i.e. later) than normal thus increasing the time for which higher torque is available during acceleration and it affects all gears. The overdrive button simply engages/disengages top gear but does not affect the lower gear shift speeds.
HTH, regards.
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Highlander
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13 Scorpios, XR4x4, Suzuki SJ413 for off road :)
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Re: overdrive
« Reply #18 on: Mar 17th, 2009, 8:05pm » |
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Sorry maybe i should have explained in a bit more depth.
For maximum acceleration depress the OD button so that the green light shows on the dash eg top gear is disabled (you can still hit 100 in 3rd easily)
Pressing the S button will as stated above hold the gearchange until 6000 rpm meaning the engine can produce maximum torque.
So pressing both OD and S will give the fastest acceleration possible although the OD being disabled will only make a difference once you have reached the point where top gear would normally engage.
makes quite a difference
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on Oct 17th, 2011, 12:35pm, Simmo wrote:| I give up ! Too much for an old boy! |
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and11
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Re: overdrive
« Reply #19 on: Mar 19th, 2009, 8:52pm » |
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Interesting, must try that next time i get a chance
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