Shifting into neutral kills tranny! What?

I'm saying that no mechanical damage should occur..
I am not advising you continue that behavior, as the transmission is just one part of a synchronized system in today's vehicles, which are programed to interact together within specified parameters that are usually tailored around 'typical/normal' driving habits..

Sorry for getting back to you so late in this thread, had some other work to do so i was offline, but hope this answers your question..

 

This statement is simply not correct..
I would have to ask what your professional credentials are when giving advise like this & the mechanical reasoning behind this declaration..

No offense intended..

 

As mentioned before, shifting an auto into neutral to go downhill makes no sense since it actually consumes more gas than just leaving it in drive and taking your foot off the gas. Coasting with the injectors off is one of the best MPG tricks available on this truck. Putting it into "N" is a waste.

 

Thanks. Yeah I don't coast in neutral it was more of a curious thing.

 

While it is the internet and people can do/say whatever they want to-true or not. The ASE Master Tech name and badge on his Avatar...are probably a good indication. He also gave a pretty solid technical explanation that makes sense. Jus saying...

 

Since this what brought up by the OP and since we have a mastertech here could I inquire about the hard shifting issue? I just got mine used so I don't know if it is normal or not but I noticed that it revs up and engages gear late when getting to speed i.e going through the lower gears from a dead stop. I have heard everything from axle wrap to ECM faults to explain it but I was wondering if anyone could enlighten me. It is a 05' V6 4l Automatic btw. Thanks!

 

Would not be easier to just read FSM?
just saying.

 

No offense taken..

I hold re-certification status for both ASE Master Certification in Automobile Repair & ASE Master Certification in Medium/Heavy Duty Truck Repair categories, my candidate ID number at ASE is 178894.

Please feel free to verify this...

 

Toyota transmissions are 'adaptive type' & should 'learn' the nuances of the operator & shift accordingly (in a perfect world of course).
Most transmissions today though can be 'programed' to shift at any given speed/engine RPM. However, this involves software changes that usually must be implemented initially by the manufacturer.. it is after all their code, & most manufacturers are generally not keen about sharing things like that...

 

What you are doing does not hurt anything. As was mentioned, manual transmissions are splash lubed, and so long as the engine is spinning the input shaft on a manual, the gears will be lubricated.

As for automatic transmissions. Yes the front pump is driven by the torque convertor. What I did not see mentioned, is that the fluid is ultimately your medium for transferring power from the engine to the rest of the drivetrain. Putting an automatic transmission in neutral SHUTS OFF fluid flow through the pump. If you wish to verify this, simply remove one of the lines from the transmission cooler. When you put it in neutral, fluid flow will stop. This means your planetary gearsets will NOT be getting any fresh fluid supply to continue being lubricated.

Leave it in gear on hills. If you read your states driving manual, you will likely read that coasting downhill in neutral is illegal anyway.

 

Manuall says not to tow auto tranny in Neutral and rear wheels on the road unless it is emergency and tow happens on hard surface and low speeds for short distance.
Reading through FSM looks like low speed is below 30MPH Their reasoning is probably that tranny is synchronizing always to first gear when on neutral because its a first gear that tranny engages when putting on D regardless of speed. So it is probably not good idea to run on neutral unless you are at super low speeds. Just what I gather from FSM

 

Factory Service Manual? Would that tell me what could cause my hard shifting? I'm not a grease monkey just a twigget so this is all new to me.

 

....I'm just gunna stop doing that, but the 9 mile limit astounds me.

 

I'm sorry to say but this is just more incorrect information..
It is a direct mechanical connection from the engine/torque convertor that drives the transmission front pump. No fluid connection involved.
There are many sites on the Internet which will inform you of the basic operation of an Automatic Transmission, these basics functions have not changed for some time, some functions however have been "modified' (for lack of a better term) to improve performance.
The pressure supply pump in a Automatic Transmission is 'gear" style pump similar in fashion of most engine oil pumps, it's job is to supply a constant volume of fluid at a minimum pre-determined pressure, it is a simple mechanically operated device & cannot be randomly 'shut off' or 'turned on'. There are various solenoids, switches. pistons, valves, sensors, etc, however that are responsible for controlling such functions, & one is to maintain proper operating temperatures.. Wouldn't it make sense to discontinue the flow of fluid that is at the correct 'operating temp' to a cooler when there is no 'load' (ie-heat transfer) on the transmission (ie-neutral/park), or if the fluid is not at presently 'operating temp' in order to maintain the correct range of operation?

You avoid towing a vehicle by the 'drive' wheels (or definitely limit the tow speed) with an Auto Trans so as not to 'cook' the trans, because the vehicle is not running, & therefor no fluid is flowing about the trans (Engine is connected to convertor, convertor runs pump, pump moves fluid, fluid lubes, cools, & operates trans...)

Hope this clears things up...

 

Thanks.. but they're nothing new, I've held those certs (& been twisting wrenches for a living) for quite a while now.
Wouldn't have brought them up tho if you weren't wondering, or hadn't questioned it..
Just trying to help out here & perhaps clear up some misconceptions if I can..

Not trying to be argumentative..

 

I hate the fact that I'm arguing with a master tech. I'm going to stick to my guns here. Yes, the engine is BOLTED to the torque convertor housing. A torque convertor is not a one piece lump of steel. It is a hydraulic turbine meant to allow for a slip coupling when the engine is running, and the vehicle is stopped. It is hydraulic pressure generated by the fluid being forced between blades in the torque convertor that generates forward (or rearward) motion. As such, an autmatic tranny is very much a fluid drive transmission. Modern torque convertors do have a lockup feature, that will make the coupling solid at speed.

I have never heard of any "optimum" operating temperature for an automatic transmission - only that they should not be allowed to run north of 250 degrees for any length of time. There is no thermostat that I've seen in any schematic diagram of an automatic tranny.

Putting the transmission in neutral does not just stop flow into the cooler. All fluid pressure is diverted back to the pan to decouple all of the planetary gearsets, as well as the flow through the torque convertor to avoid unnessesary heating of the torque convertor itself.

 

X2 - And anyone can guess...

 

Hmmmmmm. The piece of information about automatic transmissions that is left out of this discussion is the fact that modern transmissions can electronically vary the line pressure in the unit. Since the decisions about pressure are made by several conditions (one of them being if the transmission shift selector is in D or N) shifting into N could drop the pump pressure to almost nothing. Since physics ALWAYS works, when the pressure of the fluid drops, not as much will flow through the passages, and this is why some vehicle can exhibit an oil starvation in N while coasting or towing. This is also why some vehicles are a little more of a challenge to use a transmission flush machine on. If the machine relies on the fluid pressure and flow from the trans to exchange the fluid and you try to perform this with the vehicle in park or neutral, it will take FOREVER. (up to 30 minutes) Take the same transmission and shift it into gear, the line pressure comes up, and the fluid flow increases. The transmission fluid is exchanged in a matter of minutes. End of story.


Some vehicles are designed to be towed behind a vehicle and some are not. Those trucks that are may be equipped with a transfer case that has an N position as well. That would decouple the splash lubricated transfer case from the flow lubricated transmission.

I applaud anyone that has taken the time and effort to certify as a technician. The trouble with automobiles is that they do not all work the same. Just because one model works one way does not mean they all do. So I am not being argumentative either. I answer lots of questions with "It depends" because that is the only way to do it.

 

I think you are confusing the convertor impeller/pump with the pump that provides fluid volume/pressure to the transmission assembly itself.

If you have ever worked on an auto transmission, simply checking system pressures requires the procedures to be done both "cold' & at operating temp.
When checking fluid, on most dipsticks (if there is one) it states to check level when "hot", this alone implies an operating temperature preferred range.

The following is quoted from one of the links posted below..

"The transmission oil pump (not to be confused with the pump element inside the torque converter) is responsible for producing all the oil pressure that is required in the transmission. The oil pump is mounted to the front of the transmission case and is directly connected to a flange on the torque converter housing. Since the torque converter housing is directly connected to the engine crankshaft, the pump will produce pressure whenever the engine is running as long as there is a sufficient amount of transmission fluid available. The oil enters the pump through a filter that is located at the bottom of the transmission oil pan and travels up a pickup tube directly to the oil pump. The oil is then sent, under pressure to the pressure regulator, the valve body and the rest of the components, as required."

Thoroughly explaining the process would require more effort then I currently have time for, as there are many sites on the Internet that provide the information you seem confused about. here are a few links;
http://www.familycar.com/transmission.htm

http://www.apsprecision.com/images/How Torque Converters Work.pdf

hope these sites can clear up some of the confusion..

 

Once again, what he said. I'm ASE Mastertech certified, too. I know older Dodges will not send fluid to the cooler when in park, but I honestly can't think of a single one that stops flow in neutral.