Masama ba mag shift s neutral in high speed?

**moxxxs** · April 9th, 2008 10:47 PM

If your main concern is FC, try to drive smoothly and keep the rpm around 2000r/min. This is possible since long drive naman bro. If you still have a few days before your trip, you may consider converting to LPG fuel. Its cheaper by the liter and is less harmful to the environment.

Another alternative in traveling this kind of distance is to take advantage of the numerous deluxe provincial buses, as well as the low fares of some airlines. You sleep as you travel and arrive there fresh and well rested.

**meledson** · April 9th, 2008 11:22 PM

Originally Posted by mbeige

Drive to Neutral = OK
Neutral at high speed to Drive = BAD

This is because the automatic transmission is not a manual, and the clutch bands will wear out easily when you shift from N to D at speed. The reason behind this is because when you're at speed the engine is at a certain RPM, depending on what gear you're in. When you shift to N, it reverts back to idle engine speed which is around 700RPM. Now, when you shift back into D, the gears and momentum will force the transmission to spin faster in order to retain its given momentum (remember first law of physics). So the parts that will absorb the brunt will be the clutch packs and torque converter and they don't like being slammed like that unlike manual transmission clutches, which can handle the "neutral drop" as they call it.

So only shift to N when you're SURE you'll be coasting to a stop, but if the light suddenly turns green and you still have momentum, you need to step on the accelerator to match the previous engine speed at that given vehicle speed (so you must know your car very well) in order to SAFELY shift from N to D.

Wow. Aray.

Thanks for the info. I do not know this.

**mbeige** · April 10th, 2008 12:47 AM

I'm actually not sure if rev-matching works, never had the courage to do it on my car though I've coasted a few times and yes, your braking distance is longer due to the lack of engine braking. Thing is, I'd rather do that to minimize the difference between engine RPM and actual RPM when the transmission finally selects its appropriate gear, rather than directly slam it in D when I'm coasting and at speed with the engine simply idling.

I've read many threads on certain boards that doing "neutral drops" (like jackrabbit starting a car, dropping the shifter to D while maintaining high RPM, to make the tires squeal, in an automatic transmission vehicle - like what some do with manual transmissions when they want better acceleration off the line) will kill the transmission. It's basically the same principle, because you're forcing the transmission to jump from idle speed (coasting in neutral) to its matched engine speed when it's finally in gear.

Maybe more experienced people can shed more light but as far as I'm concerned I'd rather not risk it, if all it takes is more gentle pedaling of the accelerator, changing driving manners, etc to obtain optimal fuel economy.

**Type 100** · April 10th, 2008 01:41 PM

Originally Posted by mbeige

I've read many threads on certain boards that doing "neutral drops" (like jackrabbit starting a car, dropping the shifter to D while maintaining high RPM, to make the tires squeal, in an automatic transmission vehicle - like what some do with manual transmissions when they want better acceleration off the line) will kill the transmission.

Slightly OT:
Yep that seems to be the case.

Autocar's preferred method of launching A/T-equipped cars in its annual 0-100-0 mph contest is to pre-load the torque converter with engine revs while holding the brakes. No "neutral drop" there but I'm not sure if it's any less damaging to the transmission either

**mbeige** · April 10th, 2008 01:49 PM

Ah, I think that's what's called as power braking? Yep, automatics are very sensitive to these things compared to manual transmission cars.

**niky** · April 11th, 2008 11:35 PM

torque braking is bad on the transmission if you do it too many times. Possible transmission fluid degradation from heat build-up... but it's nowhere near as destructive as a neutral-drop... which will wreck the clutches four-ways-to-sunday.

Torque-braking is my preferred launch method. Great on diesels which can overpower the tires at low rpms, but it's still not as good on non-turbo gasoline cars.

**niky** · April 11th, 2008 11:35 PM

torque braking is bad on the transmission if you do it too many times. Possible transmission fluid degradation from heat build-up... but it's nowhere near as destructive as a neutral-drop... which will wreck the clutches four-ways-to-sunday.

Torque-braking is my preferred launch method. Great on diesels which can overpower the tires at low rpms, but it's still not as good on non-turbo gasoline cars.

**Type 100** · April 11th, 2008 11:41 PM

Interesting input Niky. Thanks for the info!

Like I mentioned, Autocar does this for its annual 0-100-0 mph shootout. A fair number of their usual entries are Benzes with loony power outputs: Brabus CV8, Merc S600L, Digi-Tec CL600...

**hcdangan** · April 15th, 2008 07:57 AM

Guys I have a City IDSI with automatic CVT tranny. So how does this engine brake thingie work? Sorry for the noobish question. I just got the car a month ago and I'm also a new driver.

**userfriendly** · April 15th, 2008 08:23 AM

Originally Posted by hcdangan

Guys I have a City IDSI with automatic CVT tranny. So how does this engine brake thingie work? Sorry for the noobish question. I just got the car a month ago and I'm also a new driver.

engine braking is using the engine to slow down the car. sa AT, pag downhill ka, downshift mo to 3 or 2 para magslow down without using your brakes. Useful for steep long downhill descents like going down baguio. Kasi pag lagi kang nakatapak sa brakes sunog yun bago ka makababa sa baguio.