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Rolling Down The Hill In R33

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Modena Grand Master

Modena

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Posted (edited)

Prior to this R33 GTS-T (auto) I used to drive a VS commodore which was about 100 KG heavier... now when going down the hill the VS just rolled like crazy picking up speed. The R33 which is lighter, doesnt roll well at all...Infact the only time it rolled good was when I chucked it into NEUTRAL (i heard its bad for tranny though).

Is this OK or? Cos i feel i could be saving petrol money if it rolled better.

The car is stock with stock wheels.

Also can anyone explain to me whats the go with over drive? I got cruise control and when i turned it off while cruising on 100 KM/h the revs jumped from 2.5 K to over 3.5 K and it slowed the car down so i turned over drive on.

Cheers

Edited by Sir-D
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_8OO5TED_ Mentor

_8OO5TED_

Posted
Posted

overdrive is a "4th gear"

so u drive around looking for hills to "roll" down to save money on fuel? Sorry im just trying to understand exactly what your getting at here thats all.

Rolling will mean u will sit on the brake more and wearing your brake pads quicker?!

Modena Grand Master

Modena

Posted
  • Author
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overdrive is a "4th gear"

so u drive around looking for hills to "roll" down to save money on fuel? Sorry im just trying to understand exactly what your getting at here thats all.

Rolling will mean u will sit on the brake more and wearing your brake pads quicker?!

So i should always have over drive on ye?

no i dont look for hills :( its just whenever im rollinw down to the traffic lights that are about to turn red i still have to gas it a bit otherwise i lose all my tempo, the commodore had over 270000 KMs though, this one has 44000. Just trying to work out how i could make it roll bit better.

Wink Grand Master

Wink

Posted
Posted
So i should always have over drive on ye?

Yes. It saves the most fuel and for power its okay because the car will know when you want to fang it and switch off overdrive itself.

I have only turned it off for dyno runs.

smurf80 Experienced

smurf80

Posted
Posted

It rolls worse? Its actually ilegal to have your car in neutral while moving as its classed as not being in control of your vehicle.

As others have stated overdrive is 4th gear. Its the same as rolling down a hill in first in a manual unless you put your foot on the pedal you will only roll at a certain speed.

blind_elk Grand Master

blind_elk

Posted
Posted

It may be related to the TPS - Skylines in general cut fuel to the injectors when the throttle closes and the engine is above about 1200 rpm. The Commodore might not do this.

I know my R30 only does the fuel cut above 3200 rpm, so it rarely cuts fuel on throttle backoff. As a result, it tends to drive down hills. My R32 does do fuel cut, so it basically maintains speed down hills. It's almost like an engine brake.

grigor Rising Star

grigor

Posted
Posted

Having both auto Skyline and VS dunnydore, so I know what he's talking about.

The VS auto, especially around town, doesn't lock up at moderate speeds, so when you roll downhill, you notice the tacho drop down to a fast idle. (Really great for getting booked by the coppers hiding at the bottom of the hills.)

The Skyline locks up at a much lower speed, It's quite noticeable when you swap from one car to the other. Makes you think you're still in 3rd, but at least you don't have to roll downhill with the bloody brakes on.

Modena Grand Master

Modena

Posted
  • Author
Posted
Having both auto Skyline and VS dunnydore, so I know what he's talking about.

The VS auto, especially around town, doesn't lock up at moderate speeds, so when you roll downhill, you notice the tacho drop down to a fast idle. (Really great for getting booked by the coppers hiding at the bottom of the hills.)

The Skyline locks up at a much lower speed, It's quite noticeable when you swap from one car to the other. Makes you think you're still in 3rd, but at least you don't have to roll downhill with the bloody brakes on.

Thanks dude. Commodores arent that bad though :laugh:

  • 3 weeks later...
benro2 Community Regular

benro2

Posted
Posted

I think it's mostly due to the gear ratios. The Skyline auto does around 3000 rpm in top gear at an indicated 110km/h, while the Commodore is doing around 1800 rpm in top gear at the same speed.

We've had a pile of Calais' over the years (company cars) and I swear, every gearbox has been programmed differently. There is a large hill near our place where you start out at about 90km/h and by the end in the Calais you will be doing around 115km/h, but in the Skyline you would probably only hit 100km/h if you're lucky. In the first Calais' the revs used to hold at whatever they would have been with the accelerator depressed in top gear, then a couple of cars after that used to drop revs to idle, then raise them back up, then drop, etc. Then another one would just drop them to about 1200rpm all the way down the hill. The one we have now (5 spd auto) seems to keep revs as if you are in top gear, like the first cars. Dunno why they keep on changing, but I suspect they're to do with how the transmission logic is programmed.

Oh yeah, I had a point to all that... the cars that kept the revs equal to top gear (locked torque converter?) seem to roll the best. The Skyline seems to drop revs slightly when you lift your foot off, so I suspect the torque converter becomes unlocked, so possibly that puts extra drag on the engine, and combined with lower gearing (more engine braking because of increased revs), that may account for the extra rolling resistance?

Also, just out of interest, the Calais has an instantaneous fuel consumption feature on the trip computer, and all cars except the ones that used to raise and drop the revs intermittently read 0.0L/100km all the way down the hill. Dunno if that's actually true or not, but it sure would be nice! :(

Also, I just keep overdrive turned on all the time. That's certainly the way to go if you're trying to save fuel. I find the car's fine at all speeds like that - the transmission seems a lot more responsive than any of the Calais' we've had, even the newest one with the 5 spd auto!

Modena Grand Master

Modena

Posted
  • Author
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oh... oh dear... over drive !! lol, do the 1994 r33 gts's come with an over drive? Cause for that Newcastle Cruise I was sitting on 3k+ the whole way and back haha, how do I turn it on/off??

theres a button O/D on ur auto shifter...

when its on it should not glow on ur dash board... when its off it will glow OD or overdive.

post-23785-1146094274.jpg

benro2 Community Regular

benro2

Posted
Posted
oh... oh dear... over drive !! lol, do the 1994 r33 gts's come with an over drive? Cause for that Newcastle Cruise I was sitting on 3k+ the whole way and back haha, how do I turn it on/off??

I assume the gear ratios are the same for the S1 and S2 auto's, so I'd say you'd already have the overdrive on if you were doing around 3000 rpm at around 100 km/h. You'd be doing over 4000rpm if you had it off!

Damn I wish they had a 5th gear so you could cruise at 2000 rpm down the motorway - would be quieter, save fuel, less wear and tear... I know you'd have almost no torque at that speed but the auto's kick down pretty fast on light throttle so that probably wouldn't matter. Oh well, I can only dream... :devil:

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