Another DCT trans question

[dduelin]

Consider an example where the DCT bike is in fourth gear and you are going to down shift, third gear on the other clutch shaft is in mesh, shift dogs engaged, ready to transmit torque when the clutch engages. If the DCT instantly disengaged the fourth gear clutch and engaged the third gear clutch there would be an engine speed mismatch. The engine has to rev-up to match road speed in the lower gear.

With out the throttle blip feature of the Africa Twin and Gold Wing, the DCT uses the clutch to pull the engine up to speed during a down shift.

The transmission pre-selects the next gear when you push the upshift or downshift button, or the software makes the decision for you if in auto.

Regardless how it does it when you are doing say 50 in 6th and downshift to 5th, then 4th, then 3rd the road speed does not change from 50 and the rpms match 3rd at 50 mph with three presses of - button. A manual gearbox would require a throttle blip with each gear change to hold a steady speed but the DCT box doesn't. At least that is how my 2015 was.

 

[the Ferret]

Look what You have started


Anyway I think Your question was answered in the second post.

I know. You'd think I'd asked a question about tires or something

Of course, if I was patient and just waited for my bike to come in, and then read the owners manual and rode it, a lot of my questions would be answered, but then what fun would that be?

I have learned an awful lot about the bike so far here and I appreciate everyone's input (even if y'all can't agree on ANYTHING lol)

 

[TacomaJD]

I know. You'd think I'd asked a question about tires or something

Of course, if I was patient and just waited for my bike to come in, and then read the owners manual and rode it, a lot of my questions would be answered, but then what fun would that be?

I have learned an awful lot about the bike so far here and I appreciate everyone's input (even if y'all can't agree on ANYTHING lol)

It's easy to learn how it works. I pretty much learned on the bike after I bought my first one a couple years ago. The computer won't let you do anything "wrong" in terms of shifting, so no worries there. And if you're like me, you'll grow to love the DCT. I still like changing gears on my cruiser, and I've said this before, but knowing what I know now about DCT motorcycles, I'd probably have at least 1 DCT bike in the stable even if I had two good legs!

DCT bikes are kind of like cruiser bikes. I probably wouldn't have a cruiser bike either if it weren't for the feet-forward positioning working for my particular leg circumstances. But since I was initially "forced" to ride cruisers after recovering from my wreck, I've grown to love them, just as I have the DCT after discovering it 7 years too late LOL. I love my cruiser, big comfy seat, big windshield, plenty storage. It's just the perfect bike to bang out some miles on with the lady on the back.

 

[dduelin]

With the 2021 changes coming I honestly missed having a DCT NC so much I inquired several times at my favorite dealer starting about a month ago. He was getting a XD in (was supposed to ship from warehouse 5/27) but I resisted making a deal early last week and someone else stepped in ahead of me and bought it. Oh well, wasn’t meant to be.

 

[bigbird]

I talked with the manager of a small rural family owned dealership yesterday.
She actually phoned me to inquire about my opinion of the pricing of an F6B she is selling on consignment for a customer.
I asked her about the '21 NC's situation in Canada.
She said if she hadn't ordered one last fall, then she couldn't get any stock for 2021.
But at the same time, the '21 NC was not even listed in the dealer's order book back then.
Talk about a paradoxical situation.
So it seems the only dealers in Canada getting '21 NC's are the Powerhouse dealers.
They get the first and sometimes the only crack at new bikes.

 

[DCTFAN]

If there is only one shift drum, how can the fourth gear dogs be engaged and transmitting power, and the third gear dogs also be engaged. Does the shift drum have combined steps not found on a manual transmission shift drum, such as 3 and 4 together, then 4 along with 5, then 5 and 6? In other words, the shift drum slot pattern always has two sequential gear dogs engaged at any time? I had not thought about it that way before, but it makes sense.

That way if the rider were going to manually upshift or downshift from a mid ratio gear (2-5), there is a 50-50 chance on whether the shift drum has to move to shift, or stay where it is.

Exactly this. The solution they found (key to DCT design) is two concentric cylinders with odd and even gears attached to each.
There is actually only a < 10% (WAG on my part) of the ECU preparing the wrong next gear. This is because the algorithm takes into account all the prior inputs from the engine / rider.
Unless you purposely use the toggle to override the ECU, it is most likely in the right gear.
There is no IMU (inertia measurement unit) in any DCT except the newer 2020 models. The older models had an algorithm based detection for uphill/downhill using the basic sensors.
Sometimes the situation arises where the inputs don't 'fit' the parameters and the gear shifts up while going downhill. It's not perfect, yet.
I upgraded my 2016 AT which had similar feature set as the 2nd gen DCT on the NC.
The 2018/2019 AT's have TBW (throttle by wire) which opened a host of new features they could add; one of which is the auto-blip already mentioned.
Is it necessary? Not really and unless you get used to it (I didn't) it becomes annoying.
IMO, they decided to implement it anyway because with TBW it was only a few add'l lines of coding and it does smoothe out the initial clutch bite.

 

[Deleted member 1183]

Ok. As I said above I only ever used the bike in manual once and that was my recollection. My (X-Adv) has 2017 tech. I will be riding it tomorrow and I will give it a try in manual once more if I think of it.

Ok to follow up on my previous comment I put the trans in Manual. I then ran it up to speed as far as 5th gear and allowed the bike to slow down. When the revs dropped to about 1600/1700 the transmission dropped to the next gear automatically. I didn't allow it go all the way beyond third but the point was made at least on downshifts in manual. I may however have made an incorrect assumption with regard to upshifts in Manual.

So in summary my 17 gearbox downshifts automatically even in manual mode if the revs drop below about 1700rpm.

 

[Wheels]

Studying the PDF on the ST DCT.
I just assumed output shaft was one gear and the dual clutches were primed for
up/down from the output shaft. You can't skip gears with the DCT.