Jump to content
SAU Community

Recommended Posts

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
Link to comment
https://www.sau.com.au/forums/topic/112115-rolling-down-the-hill-in-r33/
Share on other sites

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?!

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.

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.

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.

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.

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.

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...

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!

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

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:

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


  • Similar Content

  • Latest Posts

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
×
×
  • Create New...