I started driving stick shift many years ago but now I am driving most automatic cars for the past ten years or so. I still have a habit of shifting into Neutral when I am stopping at a red light or stopping for a long period of time. I have been doing that with our '96 MPV, then 02 MPV, and other Japanese makes as well. I heard on BMW with ZF automatic transmission, shifting in and out of D position to N position damages transmission. But on the Japanese cars I drove I got excellent results: the auto fluid seems to last longer and I have no issues with my cars driving this way. With the CX-9 that allows me to shift manually, I think it is ok to shift into N when I stop and into D when I go is quite a normal thing, and this practice should not harm the transmission in anyway right?
Shifting In and Out of Neutral
- Thread starter mzd
- Start date
- :
- 2022 CX-5 Turbo
Personally, I only shift to N when I predict that I will stop for a few minutes such
as I just miss the green or stop at R&R crossings (long and slow cargo trains around here).
I'll call BS about the BMW ZF. I had BMW 540iA (w/ ZF tranny). I did the same, and there was no
ill effect till I sold it after 10 years.
as I just miss the green or stop at R&R crossings (long and slow cargo trains around here).
I'll call BS about the BMW ZF. I had BMW 540iA (w/ ZF tranny). I did the same, and there was no
ill effect till I sold it after 10 years.
Yeah, I also think ZF auto damage due to shifting to N is BS too, glad I am not alone on this. My cousin who is a mechanic and used to drive his 80's 5 series told me that story. It's good to know it's not true.
I guess my habit of shifting to N when I am at a red light is ok then. See this explanation:
http://www.topgear.com.ph/features/...really-shift-to-neutral-when-stuck-in-traffic
I guess my habit of shifting to N when I am at a red light is ok then. See this explanation:
http://www.topgear.com.ph/features/...really-shift-to-neutral-when-stuck-in-traffic
Maybe I am just lucky, but my Maxima which has 105K on the odo is still running fine. Driving it since Dec/04 until now, I only change the transmission fluid once and the fluid itself is still red with no burning smell. Recently when I visited the Maxima forum, I realize lots of folks driving 6th gen Maxima report to have transmission problem due to a defective valve body assembly that causes the shifting to malfunction. It is a very expensive repair and Nissan has redesigned this part to correct the problem, but owners would have to pay for the repair and part costing them around 2K. My Maxima inherits this defective part yet I have not yet seen a shifting problem. I think the fact that coming from driving stick shift habit, I always shift to Neutral at stop light or when I stop for long period of time may prevent the transmission fluid from getting too hot and the clutch disks don't get to wear down as much and therefore the 3 solenoids that work the shifting functions don't get stuck (Maxima transmission fails because solenoids get stuck) and I am still able to get away from the transmission problems other Maxima folks suffer; I don't know for sure, but I will definitely drive my CX-9 the same way I drive my Maxima. But I am going to change the fluid on my Maxima tomorrow and hope it will continue to be fine.
flatlander937
Member
- :
- '11 Mazda2 Sport
I can't speak for any transmissions in particular... but MANY transmissions do not circulate fluid through the transmission cooler(if equipped) in certain gears... Park is usually the one that does NOT circulate on big Dodge 3500s and stuff... when the trans starts to overheat you need to pull off the road and let it idle in neutral.
Usually whatever gear you are supposed to check trans fluid level in(I think on Mazdas it is PARK), means it is flowing fluid. Frankly I'm unsure of what is happening in neutral as I don't have access to a power flow diagram.
In general though(with transmissions I'm more familiar with), with shifter in drive... it is the forward clutch and one way sprag clutch which gets engaged when you put it into drive. Most stuff uses a roller clutch now for cost reasons, and frankly sprags are not necessary unless you are pushing stupid power. (for the sake of power flow, sprag and roller clutch is an interchangeable term). You can read up on sprags vs rollers in TH400 transmissions for drag racing applications. It really doesn't matter in your situation since you're not launching a car with 700hp. In a nutshell: the act of just shifting from neutral to drive will not put any noticable, significant, or even measurable wear on your transmission.
There are no clutches applied at all in neutral in any applications I know of.
I will also add that having clutches applied in drive while sitting at idle causes zero wear because they are not slipping. It's the same as putting a manual transmission in neutral... the clutch is "engaged"... and stuff is spinning inside... it's just not going anywhere.
The only thing slipping is the torque converter because it has not reached it's stall speed(google torque converter stall speed if you want to learn more)... and they just don't wear out... it's a fluid connection. They can fail entirely, but it is never from sitting in drive at idle so it's a moot point as well.
Here is a service manual online for a 4spd Chrysler transmission I'm a bit more familiar with for reference if you want to read up on how it works and what is applied when:
http://www.mopar4life.com/autoindex/downloads/PDFs/46re-manual.pdf
And here is a generic learning about auto transmissions PDF I found that really dumbs it down and explains what's going on:
http://www.autoshop101.com/forms/AT05.pdf
It's very good as it's much shorter. It involves a 3spd auto transmission but all the principles are exactly the same. The only difference with a 4/5/6spd auto trans is that there are more drums containing more clutch pack assemblies and more servos with more planetary gear sets to achieve more speeds.
IMO: shifting in neutral at a stop won't do a damn thing to affect life of it in most cases. Honestly I have no idea about the BMW situation, but they do some goofy s*** on the rest of the car so it wouldn't surprise me if they make it self destruct when you shift into neutral(braindead Leaving it in drive won't do anything worth mentioning either. I know that in drive, you can be positive that fluid is being cooled if you have a trans cooler. In neutral it may or may not be, but it likely is.
What putting it in neutral at a light will help is if you just did a real hard panic stop and now your brakes are hot as hell. You'll cook the rotors and warp them if the pads are super hot and you are holding the car in place with them for an extended time after getting them hot. This will usually never happen from one or ever 20 applications of doing so, but doing it on a regular basis will eventually net you a shimmy in the steering wheel when you are braking from high speeds.
(boom01)
Usually whatever gear you are supposed to check trans fluid level in(I think on Mazdas it is PARK), means it is flowing fluid. Frankly I'm unsure of what is happening in neutral as I don't have access to a power flow diagram.
In general though(with transmissions I'm more familiar with), with shifter in drive... it is the forward clutch and one way sprag clutch which gets engaged when you put it into drive. Most stuff uses a roller clutch now for cost reasons, and frankly sprags are not necessary unless you are pushing stupid power. (for the sake of power flow, sprag and roller clutch is an interchangeable term). You can read up on sprags vs rollers in TH400 transmissions for drag racing applications. It really doesn't matter in your situation since you're not launching a car with 700hp. In a nutshell: the act of just shifting from neutral to drive will not put any noticable, significant, or even measurable wear on your transmission.
There are no clutches applied at all in neutral in any applications I know of.
I will also add that having clutches applied in drive while sitting at idle causes zero wear because they are not slipping. It's the same as putting a manual transmission in neutral... the clutch is "engaged"... and stuff is spinning inside... it's just not going anywhere.
The only thing slipping is the torque converter because it has not reached it's stall speed(google torque converter stall speed if you want to learn more)... and they just don't wear out... it's a fluid connection. They can fail entirely, but it is never from sitting in drive at idle so it's a moot point as well.
Here is a service manual online for a 4spd Chrysler transmission I'm a bit more familiar with for reference if you want to read up on how it works and what is applied when:
http://www.mopar4life.com/autoindex/downloads/PDFs/46re-manual.pdf
And here is a generic learning about auto transmissions PDF I found that really dumbs it down and explains what's going on:
http://www.autoshop101.com/forms/AT05.pdf
It's very good as it's much shorter. It involves a 3spd auto transmission but all the principles are exactly the same. The only difference with a 4/5/6spd auto trans is that there are more drums containing more clutch pack assemblies and more servos with more planetary gear sets to achieve more speeds.
IMO: shifting in neutral at a stop won't do a damn thing to affect life of it in most cases. Honestly I have no idea about the BMW situation, but they do some goofy s*** on the rest of the car so it wouldn't surprise me if they make it self destruct when you shift into neutral(braindead Leaving it in drive won't do anything worth mentioning either. I know that in drive, you can be positive that fluid is being cooled if you have a trans cooler. In neutral it may or may not be, but it likely is.
What putting it in neutral at a light will help is if you just did a real hard panic stop and now your brakes are hot as hell. You'll cook the rotors and warp them if the pads are super hot and you are holding the car in place with them for an extended time after getting them hot. This will usually never happen from one or ever 20 applications of doing so, but doing it on a regular basis will eventually net you a shimmy in the steering wheel when you are braking from high speeds.
(boom01)
- :
- 2022 CX-5 Turbo
My new experiments show that, both in D or N gears while sitting at red lights do not change
transmission fluid temperature a bit. In fact, it seems that the fluid temp of CX9 is tied to water temp
(is the tranny fluid routed to the radiator for cooling? I seem to recall reading this.). When warmed up,
both water temp and tranny fluid temp are between 190 to 200F.
transmission fluid temperature a bit. In fact, it seems that the fluid temp of CX9 is tied to water temp
(is the tranny fluid routed to the radiator for cooling? I seem to recall reading this.). When warmed up,
both water temp and tranny fluid temp are between 190 to 200F.
nazgul350r
Member
- :
- 03 MSP & 08 CX-9 GT
The tranny is connected to the radiator. This is also why the tow package has an extra heat sink on the rad fans.
