DCT - Is it possible to switch to N while driving?

[mission]

Hi,

I'm wondering if it'd be possible to switch to neutral gear while riding, in Auto mode.
For example while going down the hill. Then switch to D mode without stopping.

If yes, is it safe (for the engine/gearbox) to do so?

Thanks!

 

[dduelin]

It is impossible to switch to N while the motorcycle is in D or S and moving. Once the motorcycle is in motion in D or S the operator must bring the vehicle to a stop before switching to N. The software prevents it.

 

[davidc83]

Also, in many states, it is illegal to drive in neutral (even though probably would never be pulled over for it, would be almost impossible to prove). oops, sorry, didn't see OP was in a different country...

 

[DirtFlier]

Even it it was possible, why would you want to put it in Neutral while riding down a hill? You're not saving any measurable fuel and this practice is much harder on the brakes.

 

[DCTFAN]

Even it it was possible, why would you want to put it in Neutral while riding down a hill? You're not saving any measurable fuel and this practice is much harder on the brakes.

That really depends, on how steep the downhill is and how long it goes. There is always a specific reason for something.
Is "just because" a reason?
AFAIK, the only way you can do what the OP wants is to cut the fuel using the kill S/W (don't give any more throttle or you will kill engine), once the downhill portion is done, turn it on and give gas.

This is not coasting in neutral because the gear is still engaged.
Would I ride this way? NO.

 

[ste7ios]

Every FI engine has DFCO (Decelaration Fuel Cut-Off). There is no need to kill the engine to save fuel in that case... Just let a gear to keep running the engine from the wheels...

 

[670cc]

With a sequential gearbox, this would be a bad idea even with a manual transmission and clutch. Since to get to neutral from some higher gear with either a DCT or manual, you have to pass down through the gears to second, then to neutral. If the bike were traveling at say, 60 mph of 100 kph, the rev mismatch by the time you get down to second would be severe. Then when you have gotten it to neutral, what happens when you want to re-engage the gears? You have a rapidly spinning countershaft and a slowly spinning input shaft, and the shifting fork is trying to slam the dogs into an adjacent gear and synchronize the shaft speeds. CRUNCH! into second, then smaller crunches back up to the gear you were in when it all started.

It's good that the DCT brain is smart enough not to let this happen.

However it would sure be nice if the DCT bikes had a clutch lever tied to an electrical switch that would allow the operator to disengage the clutch(es) anytime they chose.

 

[Brillot2000]

Honda Engineers were really thinking about this scenario and put in a countermeasure/interlock in place to prevent this from happending.

I have been personally playing around many different scenarios regarding the subject. Here's what I found out. It is possible to shift into neutral while moving at a maximum speed of 2 MPH, 3 MPH or more will not do anything when the "N" button is pressed.

Regarding the shifting sequence, the DCT's shift pattern is N-1-2-3-4-5-6. As we all know that the industry standard for manual trans are 1-N-2-3-4-5 and sometimes 6.

I am not quite convinced as both clutches can be disengaged at the same time when the counter shaft is indicating there is motion at the rear wheel. I do believe that there has to be no motion being detected to get the system to disengage both clutches at the same time. This an educated guess at best.

 

[DC-Honda]

(don't give any more throttle or you will kill engine)

Can you elaborate on that? How will kill this the engine? (i assume by kill you mean "damage unrepairable").

Would be strange that the engineers of Honda would let something that could happen rather easily be part of the design (clumsy but warm gloves, accidently kill-switched, trying to accelerate because you're getting slower until you are slow enough to notive that the engine isn't even running anymore).

 

[supertux1]

However it would sure be nice if the DCT bikes had a clutch lever tied to an electrical switch that would allow the operator to disengage the clutch(es) anytime they chose.

Not just disengage, but progressively slip when needed. (I understand the new 2016 DCT modes slip the clutch better at low speeds?)

I took an MSF RiderCourse again this week to refresh my skills for the new bike (soon!) and this season of riding. I was on a 200cc dual sport with HUGE knobby tires (like ATV tires) that was geared so low that I had more success with the box turns and weaves starting and slipping the clutch in 2nd gear than 1st... The RiderCoach had problems (foot down, running over little cones) doing demos on this bike until I told him 'hey it likes clutch slipping in second...' haha. An odd bike for sure, I think it was made for climbing dirt hills, not delicate pavement maneuvers.

Anyway. I guess Honda probably knows about all the things that could make this bike better, but it is built to a price point. Maybe newer versions of DCT will have 'ride by wire' features where they have standard clutch lever and shifter peg that work the way you'd expect but won't let you screw up.

 

[DirtFlier]

[...i assume by kill you mean "damage unrepairable"...]

"Kill" is just American slang for shutting OFF the engine, such as by using the Engine Stop Switch and doesn't imply any mechanical damage.

 

[mike5100]

I am fairly sure that someone on this forum said they ran experiments where they killed the engine (via the kill switch) at 35 or 40 mph and on each occasion the DCT box gracefully changed the gears down all the way to 1st when it was stopped. I don't think this happened if he switched the engine off at the ignition.
Mike

 

[DirtFlier]

[...someone on this forum said they ran experiments where they killed the engine (via the kill switch) at 35 or 40 mph and on each occasion the DCT box gracefully changed the gears down all the way to 1st when it was stopped...]

I did that by accident while fiddling with something on the right hand grip. The bike was in 6th and I was going around 45-50 mph when I accidentally moved the Engine Stop Switch to OFF. When the bike rolled to a stop, the transmission was still in 6th and didn't respond to my pushing N or the downshift (-) button on the left side. I finally did get it to N so I could restart the engine but the routine seemed very inexact and aggravating.

In retrospect, had I rolled the bike to allow the transmission shafts to turn, it would have easily downshifted one gear at a time to N. The transmission shafts have to be slightly turning otherwise it doesn't want to downshift (easily) because of clash between gear teeth and this is not unlike a normal manual transmission.

 

[DCTFAN]

[...someone on this forum said they ran experiments where they killed the engine (via the kill switch) at 35 or 40 mph and on each occasion the DCT box gracefully changed the gears down all the way to 1st when it was stopped...]

I did that by accident while fiddling with something on the right hand grip. The bike was in 6th and I was going around 45-50 mph when I accidentally moved the Engine Stop Switch to OFF. When the bike rolled to a stop, the transmission was still in 6th and didn't respond to my pushing N or the downshift (-) button on the left side. I finally did get it to N so I could restart the engine but the routine seemed very inexact and aggravating.

In retrospect, had I rolled the bike to allow the transmission shafts to turn, it would have easily downshifted one gear at a time to N. The transmission shafts have to be slightly turning otherwise it doesn't want to downshift (easily) because of clash between gear teeth and this is not unlike a normal manual transmission.

The kill S/W only cuts power to the fuel pump motor, the engine is idling, so something is not right about your scenario.???
- it should have shifted down.

Even with the fuel cut-off, all the other electronics are working; this is how the speed sensor changes the gears down.
With the fuel cut off, if you give throttle, you will use up what little fuel remained in the lines and the engine will stop-
thus you cannot restart the fuel supply and resume throttle, unless you come to a complete stop and use the ignition key.

If you just let the engine idle, even with the fuel pump shut off, you can idle long enough for the gears to go down or
stay in gear (if going downhill) and restart the fuel by switching the cutoff S/W on. I am not sure for how long, but
every bike's mileage will vary according to its normal fuel economy.


.

 

[L.B.S.]

The kill S/W only cuts power to the fuel pump motor, the engine is idling, so something is not right about your scenario.???
- it should have shifted down.

Even with the fuel cut-off, all the other electronics are working; this is how the speed sensor changes the gears down.
With the fuel cut off, if you give throttle, you will use up what little fuel remained in the lines and the engine will stop-
thus you cannot restart the fuel supply and resume throttle, unless you come to a complete stop and use the ignition key.

If you just let the engine idle, even with the fuel pump shut off, you can idle long enough for the gears to go down or
stay in gear (if going downhill) and restart the fuel by switching the cutoff S/W on. I am not sure for how long, but
every bike's mileage will vary according to its normal fuel economy.


.

Ahroo? That sounds bizarre


My non DCT shuts the motor off like a light switch upon hitting kill. Exactly the same as engaging the sidestand. Certainly no idling going on. And the fan shuts off if running. The fan will come back on if returning kill switch back to run.

DCT's will keep running with the kill switch off? Hmmph.

 

[walawn]

Not just disengage, but progressively slip when needed. (I understand the new 2016 DCT modes slip the clutch better at low speeds?)

I took an MSF RiderCourse again this week to refresh my skills for the new bike (soon!) and this season of riding. I was on a 200cc dual sport with HUGE knobby tires (like ATV tires) that was geared so low that I had more success with the box turns and weaves starting and slipping the clutch in 2nd gear than 1st... The RiderCoach had problems (foot down, running over little cones) doing demos on this bike until I told him 'hey it likes clutch slipping in second...' haha. An odd bike for sure, I think it was made for climbing dirt hills, not delicate pavement maneuvers.

Anyway. I guess Honda probably knows about all the things that could make this bike better, but it is built to a price point. Maybe newer versions of DCT will have 'ride by wire' features where they have standard clutch lever and shifter peg that work the way you'd expect but won't let you screw up.

I used to own a Yamaha TW200. Gotta love those tires.

 

[DirtFlier]

On every Honda motorcycle I've ever owned or had experience with, moving the Engine Stop Switch to OFF cuts power to the ignition, so in my situation described above, I rolled to a stop with the engine not running and the transmission still in 6th.

By the way, the fuel pump on Hondas typically receives a signal from the Crank Position Sensor so if the crank isn't turning, the fuel pump won't pump. As far as I know there is no direct connection between the Engine Stop Switch and the fuel pump.

 

[mike5100]

On every Honda motorcycle I've ever owned or had experience with, moving the Engine Stop Switch to OFF cuts power to the ignition, so in my situation described above, I rolled to a stop with the engine not running and the transmission still in 6th.
.

I agree with you that it must cut the spark rather than the fuel, as on every bike I have had, the engine stops instantly and does not idle. However I think further experiment is needed about what the DCT box does. The other poster was certain that the box changed down the gears as the engine revs dropped - which of course it can do if its able to take power from the battery. Also - wouldn't stopping any vehicle in 6th gear break something, or lock up the bike wheel, unless of course the DCT somehow knows it has to slip the clutch if there's no engine running and yet the bike is moving.
Mike

 

[MZ5]

Every FI engine has DFCO (Decelaration Fuel Cut-Off). There is no need to kill the engine to save fuel in that case... Just let a gear to keep running the engine from the wheels...

Exactly right. Coasting down a hill in gear saves more fuel than coasting in neutral. (Because 0 fuel use is less than idling fuel use) The proviso to keep in mind is that there is an rpm at which the ECU turns fuel back on. That rpm may vary from model to model, but it is above idle. On the VTX1800 as an example the fuel comes back on in the 2000-2500 rpm range (I forget exactly where). If you have a loud exhaust, or no muffler at all, it is super simple to know when the ECU turns fuel back on. As you decelerate in gear, the rpm where the engine begins to burble again (or backfire, if you have an exhaust leak) is where it has turned fuel back on.

 

[MZ5]

The kill S/W only cuts power to the fuel pump motor, the engine is idling...

This is incorrect. Whatever else the engine stop switch does on our bikes, it shuts off the fuel injector activation signal/pulse, meaning the fuel injector is shut off. Therefore the engine is not 'idling.'