• A few people have been scammed on the site, Only use paypal to pay for items for sale by other members. If they will not use paypal, its likely a scam NEVER SEND E-TRANSFERS OF ANY KIND.

Question Metallic noises

I was crawling in traffic at the time in 1st I don’t think they do a -1 gear
I know what you mean. I got caught in traffic moving 3-4 mph yesterday, and found the slowest my bike will travel with the clutch engaged is around 6 mph. However, dropping a tooth off the front sprocket for about a 6% overall gearing change is not going to make any noticeable difference in minimum crawl speed, in my opinion. I‘d need to put about a 9 tooth sprocket on the front to be able to crawl at 3 mph with the clutch engaged.
 
I have done a similar thing to previous bikes and it made them far easier to ride and was more fun. I ordered my 16tooth yesterday so I will see what a difference it makes.
 
I would be interested in your experience swapping to -1 tooth on front sprocket, but I don't believe it's a good idea with respect to the DCT. The alternate gearing throws it off and I've read crazy things can happen like not shifting correctly or hanging up in a particular gear. But if you try it...be sure and report back here because I'd definitely like to drop a tooth on front sprocket on my track NC!
 
When I first bought my NC, I thought it sounded funny/rattling. Went to the dealer and they told me it sounded normal.
When I watched a few videos, and heard the same sound I decided to ignore the noise and enjoy the bike.
64000 miles later it sounds the same, and runs great. Its just the normal noises in there.
 
Had something similar on my Nc700s; reckon it’s slightly loose chain so I’ll tend to that this week, but do check your chain as davidc83 says, that could rattle against swingarm. Also I found the gear shifter pivot point to be dry and a bit noisy so that has been cleaned up and greased. That will be for manual shift riders only!
 
Went out today with my 16 tooth front sprocket fitted. I am impressed with the improvement in the ride and the lack of noises. I am a novice on the nc (been riding for 50+ years on many big bikes) as I haven’t ridden it for long being in lockdown, but I have a couple of things to note.
Riding in S2 it seems to change gear very quickly, it’s in 6th in no time without labouring.
The Speedo is out in the 30-40-50mph by about 5mph and in the 70-80-90mph by 10mph. I know this as I had my sat nav on for the first time and compared the speed.
I don’t know if any of the above is due to changing the sprocket as I haven’t really got any pre sprocket change experience.
I can say I like the bike better now.
 
Went out today with my 16 tooth front sprocket fitted. I am impressed with the improvement in the ride and the lack of noises. I am a novice on the nc (been riding for 50+ years on many big bikes) as I haven’t ridden it for long being in lockdown, but I have a couple of things to note.
Riding in S2 it seems to change gear very quickly, it’s in 6th in no time without labouring.
The Speedo is out in the 30-40-50mph by about 5mph and in the 70-80-90mph by 10mph. I know this as I had my sat nav on for the first time and compared the speed.
I don’t know if any of the above is due to changing the sprocket as I haven’t really got any pre sprocket change experience.
I can say I like the bike better now.
You have changed the gearing by 6% so that would be the speedometer error. Yes, the bike should feel like it accelerates easier with 6% higher rpm at cruise.
 
Went out today with my 16 tooth front sprocket fitted. I am impressed with the improvement in the ride and the lack of noises. I am a novice on the nc (been riding for 50+ years on many big bikes) as I haven’t ridden it for long being in lockdown, but I have a couple of things to note.
Riding in S2 it seems to change gear very quickly, it’s in 6th in no time without labouring.
The Speedo is out in the 30-40-50mph by about 5mph and in the 70-80-90mph by 10mph. I know this as I had my sat nav on for the first time and compared the speed.
I don’t know if any of the above is due to changing the sprocket as I haven’t really got any pre sprocket change experience.
I can say I like the bike better now.
Hmmm This is interesting. Maybe it's my ignorance (ya think!) but I don't recall that I've seen anybody change the OEM sprocket sizes on a DCT. I think the speculation was that if measured RPMs for Front wheel or Rear wheel or pinion gear got too out of whack with each other, the DCT would throw a hissy. And that may still be true (or not) - after all, there's gotta be some tolerance for variation to allow for some different tire diameters - but you may have pushed the envelope of possibilities here.
 
Hmmm This is interesting. Maybe it's my ignorance (ya think!) but I don't recall that I've seen anybody change the OEM sprocket sizes on a DCT. I think the speculation was that if measured RPMs for Front wheel or Rear wheel or pinion gear got too out of whack with each other, the DCT would throw a hissy. And that may still be true (or not) - after all, there's gotta be some tolerance for variation to allow for some different tire diameters - but you may have pushed the envelope of possibilities here.
Different drive sprocket has no impact on the speed relationship between the front and rear wheels.
 
Different drive sprocket has no impact on the speed relationship between the front and rear wheels.


Fer sure!

But it seems as though the DCT brain can clearly detect differences between front and rear wheel speeds and "throw a shoe" if they get too different.

So, are DCT shift points controlled by engine rpm or wheel rpm? I'd guess engine rpm ... but does the DCT controller pay attention to wheel speed too? Again, I'd guess so. As a mental thought experiment, while I've not tried it, I'd expect that trying to run the engine in gear without the chain installed would not see the engine rev up and gradually shift through all the gears to 6th as if you were accelerating down a steep hill - I'd expect a fault condition instead. (Hmmm ... interesting thought. Maybe somebody else should give this a try?)

While I'm pretty sure the DCT controller algorithms are pretty damned smart, their real operating parameters are a huge mystery to me. What level of variation in some set of parameters causes a default, what variations from expected conditions are OK? It's kind like trying to figure things out by fondling goat entrails in the dark and Gasman just light a match! Not at all definitive but at least a spark of light.

Maybe my ignorance about this DCT functionality is truly phenomenal - it won't be the first time - and maybe everybody else does knows about all this. If so, I'd be delighted to learn about it. In the meanwhile, I'm just delighted to learn that it's possible to change final drive ratios without the DCT going into a sulk.

So, thanks 670cc, for kicking me off on this - I often don't know what I really think until I've written it down!
 
Fer sure!

But it seems as though the DCT brain can clearly detect differences between front and rear wheel speeds and "throw a shoe" if they get too different.

So, are DCT shift points controlled by engine rpm or wheel rpm? I'd guess engine rpm ... but does the DCT controller pay attention to wheel speed too? Again, I'd guess so. As a mental thought experiment, while I've not tried it, I'd expect that trying to run the engine in gear without the chain installed would not see the engine rev up and gradually shift through all the gears to 6th as if you were accelerating down a steep hill - I'd expect a fault condition instead. (Hmmm ... interesting thought. Maybe somebody else should give this a try?)

While I'm pretty sure the DCT controller algorithms are pretty damned smart, their real operating parameters are a huge mystery to me. What level of variation in some set of parameters causes a default, what variations from expected conditions are OK? It's kind like trying to figure things out by fondling goat entrails in the dark and Gasman just light a match! Not at all definitive but at least a spark of light.

Maybe my ignorance about this DCT functionality is truly phenomenal - it won't be the first time - and maybe everybody else does knows about all this. If so, I'd be delighted to learn about it. In the meanwhile, I'm just delighted to learn that it's possible to change final drive ratios without the DCT going into a sulk.

So, thanks 670cc, for kicking me off on this - I often don't know what I really think until I've written it down!
Very early performance testing of the NC DCT by third parties was hampered because the DCT would not work (without workarounds) on a dynamomter. If the DCT does does not detect front wheel rotation as you attempt to ”accelerate” the bike, the DCT won’t shift out of first gear.

While not an NC, I witnessed a problem on a friend’s Africa Twin DCT with a damaged rear wheel sensor. The DCT, not sensing rear wheel rotation, would allow forward travel of the bike for a few hundred feet, then it automatically switched to neutral and the bike rolled to a stop.

It appears that the wheel sensors are critical components and their failure could leave the bike limping badly.

A link to a dynamometer story: https://www.nc700-forum.com/threads/dynometer-test-configuration-dct.11103/#post-160257
 
Last edited:
Very early performance testing of the NC DCT by third parties was hampered because the DCT would not work (without workarounds) on a dynamomter. If the DCT does does not detect front wheel rotation as you attempt to ”accelerate” the bike, the DCT won’t shift out of first gear.

While not an NC, I witnessed a problem on a friend’s Africa Twin DCT with a damaged rear wheel sensor. The DCT, not sensing rear wheel rotation, would allow forward travel of the bike for a few hundred feet, then it automatically switched to neutral and the bike rolled to a stop.

It appears that the wheel sensors are critical components and their failure could leave the bike limping badly.

A link to a dynamometer story: https://www.nc700-forum.com/threads/dynometer-test-configuration-dct.11103/#post-160257
Thank you for the data point and link and thanks too to dduelin for his info in the link re: dyno testing.

My limited data and experience lead me to the following conclusions (fwiw):
  • The DCT controller does monitor front and rear wheels speeds.
  • It may not accept radical differences in front and rear wheel speeds and will throw a fault if one wheel, either front or rear, is spinning but the other is not.
  • The DCT has some tolerance for wheel speed variations that deviate from rolling on stock tire sizes - lotsa reports of folks successfully running non-stock tire sizes including my own experience w/ TKC-80s. The limit on what tire size/wheel speed variation is acceptable is not known.
  • Some deviation from stock in the final drive gear ratio is acceptable, i.e. 1 tooth smaller pinion gear seems to work OK. So there may or may not be DCT-imposed limitations on what we can do with different front and rear gear tooth counts (there are, of course, practical limits)
So, thanks, I now know a bit more but the goat entrails still call out to me for some more fondling!

Am I missing anything?
 
Back
Top