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Is dooing this bad for your gear box?
Posted: Sun Nov 29, 2009 12:38 pm
by shane1992
Hey I have a Auto swb vitara, and when Im comin up to red lights etc or rolling down hills I just whack it into Neutral and just roll the rest of the way then put it back into Drive when I slow down till about 20-30 km/h then come to a complete stop. Just wandering will that do anythign to my gear box? Like burn it out or anything cause going that fast in neutral? It just seems to be saving me abit of petty doing it.
Thanks
Posted: Sun Nov 29, 2009 6:36 pm
by PJ.zook
Mate its not going to be saving you petrol, as when you are in neutral, youre engine is using petrol to keep it turning over. When youre slowing down in gear, and the engine is injected, it will be using no petrol as youre roadspeed is keeping engine turning over.
Posted: Sun Nov 29, 2009 6:55 pm
by shane1992
PJ.zook wrote:Mate its not going to be saving you petrol, as when you are in neutral, youre engine is using petrol to keep it turning over. When youre slowing down in gear, and the engine is injected, it will be using no petrol as youre roadspeed is keeping engine turning over.
Oh really, Just that when your put it in neutral your RPM's go down to about 1000 so I just thought it be using less fuel cause the engine isnt working as hard. ??
Thanks for the info anyway mate
Posted: Sun Nov 29, 2009 7:57 pm
by PJ.zook
Fuel usage has nothing to do with RPM, you could be doing 800rpm with wide open throttle dumping heaps of fuel into the cylinders to accelerate off, or you could be doing 5000rpm down a hill using no fuel at all.
Posted: Sun Nov 29, 2009 8:01 pm
by shane1992
PJ.zook wrote:Fuel usage has nothing to do with RPM, you could be doing 800rpm with wide open throttle dumping heaps of fuel into the cylinders to accelerate off, or you could be doing 5000rpm down a hill using no fuel at all.
Oh ok, I certainly have been learning something new a day!
Posted: Sun Nov 29, 2009 8:41 pm
by PJ.zook
Contrary to popular belief, thats what the forum is for!
Posted: Mon Nov 30, 2009 6:06 am
by 11_evl
in an injected car, when your slowing down to light with no accel, the engine computer puts the injectors into decell mode. that turns the injectors off for better emission control and fuel economy.
as for the box, neutral wont hurt it but chucking it into gear at speeds might eventually do something, maybe
Posted: Mon Nov 30, 2009 8:07 am
by Gwagensteve
^ What they said
There's also a road safety reason why it's not a great idea- should you need to unexpectedly swerve to avoid something, you now don't have control over the wheels - only brakes. This might lead to a spin or worse.
I'm not trying to sound paranoid, but it is worth thinking about. I'd put money on that in an emergency situation, you wouldn't think or have time to put the car back in gear.
In fact, I bet, once or twice, you've forgotten to put it back in gear at the lights.
Not having a go- it's just an observation.
You won't hurt the box disengaging gear. As for re-engaging - it would be best to do it it the lowest possible speed.
Steve.
Posted: Mon Nov 30, 2009 9:12 am
by 11_evl
Disenguageing will hurt if you go a bit too far into reverse
Posted: Mon Nov 30, 2009 12:02 pm
by shane1992
Gwagensteve wrote:^ What they said
There's also a road safety reason why it's not a great idea- should you need to unexpectedly swerve to avoid something, you now don't have control over the wheels - only brakes. This might lead to a spin or worse.
I'm not trying to sound paranoid, but it is worth thinking about. I'd put money on that in an emergency situation, you wouldn't think or have time to put the car back in gear.
In fact, I bet, once or twice, you've forgotten to put it back in gear at the lights.
Not having a go- it's just an observation.
You won't hurt the box disengaging gear. As for re-engaging - it would be best to do it it the lowest possible speed.
Steve.
Yeah good points, especially about an unexpected situation, Wont be doing it anymore !
Thanks!