Jump to content
SAU Community

Overdrive off or on?

APA

By APA,
in Engines & Forced Induction

 Share

Recommended Posts

kjb_r33 Experienced

kjb_r33

Posted
Posted

Thats it...

Shift point from 3rd to 4th should be 141-151k's full throttle (both power and economy mode)

Around 98-106 half throttle ecomomy mode and 113-121 half throttle power mode..

Obviously no or light throttle the shift speeds will drop somewhat...

These specs are for an r31 but its still the RE4R01A transmission, same as used in the nissan patrols...

May be some slight difference from r31 to r33, but thats controlled by the ECU....

hippy Grand Master

hippy

Posted
Posted

then there must be something wrong .. cause i just went for a drive ... to cruise at 60km/hr with OD off it revs at 2600, with OD on it revs at 1600 ... thats normal right?? so why would i not have the OD on?? you are reving 1000rpm less hence using less feul ... am i doing something wrong here??

kjb_r33 Experienced

kjb_r33

Posted
Posted

Remember i said lower at light or no throttle....

60 ks @1600 is probably about right, but what happens when you touch the throttle, slight incline, wind resistance, passing a car, it drops back to 3rd, right???

And you would probably find that at 60 k's, with overdrive on, its changing up and down ALL the time, not good for transmission, and probably harder on your brakes to.

hippy Grand Master

hippy

Posted
Posted

no i don't notice changing gears much at all ... when i'm cruising at 60 i always go up to 1600rpm ... at it stays there ... with OD on that is ... else it always goes to 2600rpm ... for me i dont' notice changing to lower gears much at all ... i'm not all convinced about what you're saying ... although everyone does seem to agree so i'm probably wrong ... which means everyones driving around 60 at 2600 rpm which seems very high for me ...

  • 1 year later...
dineth Proficient

dineth

Posted
Posted

ye, in regards to what hippy is saying, im interested to know what all you other Auto R33 drivers rev to when you hit 60 km/h with the OD off. Im the same as hippy. With OD on its about 1600rpm but when OD is off it jumps to about 2600 RPM when hitting the 60 km/h mark. Would appreciate other auto guys confirming this.

Cheers.

  • Like 1
Yotis Experienced

Yotis

Posted
Posted

Hrmm.. dunno wat drugs some of these ppl are on, I've never seen anyone drive around town on 3rd gear as the highest gear and only use higher gears on the highway.

The autobox is meant to know which gear is appropriate at wat speed your on (isnt this the whole point of automatic), turnin off OD to save a gear? This is the absolute first time I've read this crap. If you like to only drive with only 3 gears be my guess, me? I would stick with wat the car was originally designed to do that is drive with all gears.

Oh i've never had my gears changed up and down between 3rd n 4th when it is in 4th on an autobox, travelling at 60km/h. Unless of course I plant my foot on 4th gear in which it downsifts to 3rd. :P

dineth Proficient

dineth

Posted
Posted

hmm so what ur saying is, its pointless to change between OD on and off regardless of what speed ur going at cos the gearbox will chose the best gear?

im still confused cos while i tend to agree with you, a lot of people in here tend to argue otherwise.

WazR32GTSt Grand Master

WazR32GTSt

Posted
Posted

what i think a lot of people have said is that 'around town' or in areas of constant changing road conditions (this means traffic lights, hills, dips, braking and accelerating often which generally happens in 60km/h zones) if you have o/d ON, then yes the car will be sitting at 1600rpm. BUT as soon as you accelerate or hit an incline of any sort you will find that the car kicks down to 3rd and once you get up the hill it goes back into o/d. factor in this sort of event happenning 5 times in the space of 5 km and you will have changed gears 10 times. plus driving like this allows the car to run under load in o/d which cannot seem good to the greabox from a logic point of view.

so if we decide to turn o/d OFF, then in the same instance as above there is ZERO gear changes with greabox wear reduced significantly.

so, what is the best thing to do?

some will say drive with o/d on, some with o/d off.

and obviously the correct answer is that its up to you.

I say driving with o/d OFF will cause the trannie to run a tiny bit hotter and also cause worse fuel economy although both will probably be an insignificant amount. Driving with o/d ON is really not for 'around town' conditions, thus why its a button-feature and not a automatic fourth gear.

Just assess the road conditions ahead of you. if there's a flat road for a long stretch then put o/d ON even if you're doing 60km/h. if you're driving in the city/inner suburbs doing 60km/h then leave it OFF to save grearbox wear. in all instances if your speed exceeds 80km/h then i can't justify having the car revving above 3000rpm for an extended period when there's another gear there so always put o/d ON at high speeds.

my 2c anyway

cheers,

Warren.

WazR32GTSt Grand Master

WazR32GTSt

Posted
Posted
hmm so what ur saying is, its pointless to change between OD on and off regardless of what speed ur going at cos the gearbox will chose the best gear?  

im still confused cos while i tend to agree with you, a lot of people in here tend to argue otherwise.

oh and i tend to think that the gearbox doresn't choose the 'best' gear, rather the gear it has been programmed to choose.

its programming is usually for fuel economy rather than reliability and i find the auto box always chooses the highest gear it can according to the load of the engine. This means that the gearbox will stay under load if it means running lower rpm, rather than changing to a better gear that puts less stress on the engine/gearbox.

LiQuid IcE Experienced

LiQuid IcE

Posted
Posted

when i drive mine it feels like o/d is actually the first gear (before 1st) coz when i take it off, even at very low speeds, the revs go up like hippy said...

i always have mine on... feels like im saving petrol ;)

Scotty Proficient

Scotty

Posted
Posted

Hey, here's a question for you,

Traditionally I've left my OD on, I guess when rolling downhill at 60km/h, I feel like I saving a few cents on petrol, cos my car is revving lower,

But can I ask you, how about turning OD off to slow down. Like in a manual, quite often people gear up (or is that down?!?) into 3rd or 2nd gear to slow down, like when you approach a turn or something. Of, late I've been doing this like when turning, go down into 2, slightly braking then accelerating through the turn. Its great fun, but what part of my car am I phucking up??? ;)

Thanks

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Kapr
      RB20DE NEO smallbox clutch.

      By Kapr · Posted

      For once a good news  It needed to be adjusted by that one nut and it is ok  At least something was easy But thank you very much for help. But a small issue is now(gearbox) that when the car is stationary you can hear "clinking" from gearbox so some of the bearing is 100% not that happy... It goes away once you push clutch so it is 100% gearbox. Just if you know...what that bearing could be? It sounding like "spun bearing" but it is louder.
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      Yeah, that's fine**. But the numbers you came up with are just wrong. Try it for yourself. Put in any voltage from the possible range and see what result you get. You get nonsense. ** When I say "fine", I mean, it's still shit. The very simple linear formula (slope & intercept) is shit for a sensor with a non-linear response. This is the curve, from your data above. Look at the CURVE! It's only really linear between about 30 and 90 °C. And if you used only that range to define a curve, it would be great. But you would go more and more wrong as you went to higher temps. And that is why the slope & intercept found when you use 50 and 150 as the end points is so bad halfway between those points. The real curve is a long way below the linear curve which just zips straight between the end points, like this one. You could probably use the same slope and a lower intercept, to move that straight line down, and spread the error out. But you would 5-10°C off in a lot of places. You'd need to say what temperature range you really wanted to be most right - say, 100 to 130, and plop the line closest to teh real curve in that region, which would make it quite wrong down at the lower temperatures. Let me just say that HPTuners are not being realistic in only allowing for a simple linear curve. 
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      I feel I should re-iterate. The above picture is the only option available in the software and the blurb from HP Tuners I quoted earlier is the only way to add data to it and that's the description they offer as to how to figure it out. The only fields available is the blank box after (Input/ ) and the box right before = Output. Those are the only numbers that can be entered.
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
×
×
  • Create New...