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NC750DCT gearbox not changing gear


spaaz

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spaaz

Hi a NC Newbie from Devon, England with DCT NC750. I am a ex TT racer with a brain injury, building a low power track bike, that I might be able to ride? I have a fused left ankle and no coordination, so could not operate clutch nor gears. My accident happened 17 years ago, I tried scooters but I need a tank between my legs.

I have acquired an NC750 DCT 2014 which I have stripped of all road bike equipment. I also have taken all the ABS system off.

 

In putting it back together to ride I have found a spare 6 block connector with 5 wires and cannot find any where for it ? A wiring diagram would be great, Can some one show me a link, Please.

The block is a 6 with 5 wires,(can't seem to attach photos ?) with

 

The bike is on the rolling road and it will not change gear. It will start and run perfectly. On starting it is in Neutral, and will engage 1st gear, will drive in 1st gear but will not attempt to change in to 2nd, doesn't matter how hard you rev it.

 

I have never ridden an NC750DCT before, so don't know how it is meant to change gear ?  I have tried D and S mode, AT and MT using the + and - buttons to no avail. it makes no attempt to change gear. Nothing .

When you slow down and apply rear brake it disengages and returns to neutral when commanded.

 

I wonder if removing the ABS has upset the DCT ? I have refitted ABS motor and sensors in the front and rear, of course the front is not turning on the dyno.

 

I would prefer to not re-install the ABS. linked braking on track is not preferable

 

If possible I would like some suggestions to enable the bike to change gear. Things to try or to tell me where the rogue connector is connected to.

 

Thank you for your help in advance.

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Chris750

Hi, sorry can't help with the connector but DCT won't work without a signal from a rolling front wheel.

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kayz1

The front wheel not turning could well have an effect, i had all sorts of problems when the lad started my Integra to show his mate how it worked whilst on the centre stand..look for and clear the fault codes.

Lyn.

 

PS: is the connector the one under the left side of the truck? if so it is for the accessories harness

Edited by kayz1
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spaaz

Thanks for the feedback, I shall try and ride around the carpark and see if it will change gear. Accessory plug, that is why we can't find its mate !! If it is has fault codes how do I clear them ?

Many thanks for your help. Nick T

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Tonyj

Got to agree , think it’s related to to the front wheel not turning

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spaaz

How do they dyno test these bikes ? is there a mode you can put it in ?

 

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Tex
31 minutes ago, spaaz said:

How do they dyno test these bikes ? is there a mode you can put it in ?

 


I think you may be the first to dyno one! :D 

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jeremyr62

They make so little power they can’t rotate the dyno drum. :shifty:

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MatBin
2 hours ago, spaaz said:

How do they dyno test these bikes ? is there a mode you can put it in ?

 

Apparently there is but another website said a Honda technician did it at a dealers using special test procedures in 4th gear, selection was done manually and the bike wheeled to the Dyno. So I am guessing the engine wasnt running at that point but was somehow locked in 4th.

Welcome along.

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Tonyj

Yes I’ve seen it ... they get this cylindrical device and attach a line to it from a good anchorage point then start then engine with the pilot on board who then says  “ I’ll give it the beans “ which is kind of odd because it says ambrosia on the the tin and if it’s making good power it will sometimes take the whole skin off the top of the rice pudding ,  I hope that helps . I know it’s a bit technical but someone’s bound to be along and get all “ I’m an engineer ( usually Brian )  and explain it in layman’s terms :0)

Edited by Tonyj
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spaaz

Hi All.

Up at my workshop this morning. re-fitted ABS pump and block connector and both wheel sensors. 

Sent my mate out around the carpark.

It changed gear as it should. D and S, MT and AT.

Then took the ABS pump off, it didn't change gear, so it proves that the ABS and DCT are linked.

Replaced pump and put it back in  the dyno.

And because the front wheel is not turning, it will not change gear.

So this proves that with out the sensor picking up rotation it will not allow the DCT to change gear.

I removed front senor and put it next to the sensor ring on the back wheel to simulate a rotation signal.

Then noticed that rear ring is much smaller than the front ABS ring.

So even if I could get signal from the front sensor on the rear disc it would give the wrong pulses per revolution.

I am going to think about what i can do to trick the ABS or keep the sensor and ABS motor on the bike.

 

If anyone has information on how Honda dealers dyno these bikes, much appreciated.

 

Any suggestions on what to try whilst on the dyno, Please.

 

Thank you for your help so far.

Nick Turner

 

 

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Andy m

I doubt Honda dealers dyno anything. Honda development will play a signal into the brake ECU via the diagnostics or just order it to change gear via diagnostic message. 

 

ABS sensors are analogue so you need a sine wave going in with the expected amplitude and frequency of the front wheel and it needs to react to the throttle. Electronically it can be simulated. Mechanically you need a polewheel of that pitch turning at the right RPM. You might be able to gear it (half the number of teeth at twice the RPM) but errors and acceleration/deceleration will be amplified too possibly to the point they become unbelievable and it stops changing gear for fear or upsetting braking. 

 

Will another front wheel on a longer cable fit on the dyno roller alongside the rear?

 

Andy

Edited by Andy m
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jeremyr62
9 minutes ago, Andy m said:

Will another front wheel on a longer cable fit on the dyno roller alongside the rear?

 

Would love to see a dyno shop owners face when you suggest that. :)

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spaaz

Hi Andy M, 

I only have half a brain, I think you mean that to fix the front sensor ring to back wheel and use the front sensor ?

I  think that can be done.

I am now dynoing an NC30, payback for my mate to ride NC750.

So I will look how feasible that would be ?

Thanks

NT 

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Andy m

If you use the rear wheel you need to know the difference between rolling radius on the two tyres and probably have the rear still connected on its own polewheel to avoid errors. 

 

The ABS is taking the analogue signal from each wheel and using a "chopping" circuit to make a square wave. If then plays the square wave  over the sine wave and counts the crossing points against  the "pulse" of the sine crossing zero volts. This way it has a rate change for angular rotation without a clock. Draw it, it will be clearer. 

 

The allowed pulse rate is fixed for a given ECU and the allowed rate of change tuned in at ABS development, so they allow for different tyre sizes by changing the number of teeth on the polewheel. There is a tolerance of about 10%.

 

It detects lock-ups (as against over rapid deceleration) or airgap problems by the simple expedient of comparing front to rear signals. If the front is locked it won't let the gearbox make things worse by pulling a clutch in, hence it freezes up. 

 

If the rolling radii of both tyres are within 10% or each other then mounting a front polewheel and sensor on the rear as well as the existing rear would work. I suspect they are not because if they were Hondasan could have used the same polewheel part number at both ends. I think you need a correct sized front tyre rolling in sync with the rear. 

 

If this has a more modern brake system you would definitely need a separate front, the stuff I work on uses the different reactions of driven and undriven wheels to detect load and gradient, but this ABS is stone age, so just get the both signals in tolerance and it'll start working. 

 

Andy

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MatBin
5 hours ago, Andy m said:

I doubt Honda dealers dyno anything. Honda development will play a signal into the brake ECU via the diagnostics or just order it to change gear via diagnostic message. 

 

ABS sensors are analogue so you need a sine wave going in with the expected amplitude and frequency of the front wheel and it needs to react to the throttle. Electronically it can be simulated. Mechanically you need a polewheel of that pitch turning at the right RPM. You might be able to gear it (half the number of teeth at twice the RPM) but errors and acceleration/deceleration will be amplified too possibly to the point they become unbelievable and it stops changing gear for fear or upsetting braking. 

 

Will another front wheel on a longer cable fit on the dyno roller alongside the rear?

 

Andy

The .com version of this website suggested a Honda technician did Dyno a dct at a dealers after updating the s/w.

A letter to Honda UK might get some info?

Edited by MatBin
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Chris750

Honda had a demo rig for DCT at the NEC bike show 2019 and the front wheel was stationary, I asked the guy on the stand how they got it to work and he said the laptop took the road speed from the rear wheel sensor and the program corrected the speed back to the bikes ECU to mimick the front wheel sensor.

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bazza

wow way beyond me but if it helps I have just been told about the "clutch initialisation procedure" on my CT DCT .Might that help on a 7 year old DCT Nc?

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Defender
37 minutes ago, bazza said:

wow way beyond me but if it helps I have just been told about the "clutch initialisation procedure" on my CT DCT .Might that help on a 7 year old DCT Nc?

It certainly won't hurt, if you can get it do it?

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spaaz

Dear Andy,

 

Now back in workshop.

 

I have had a count of the sensor signal plates.

 

Front 60

rear 50

Front tyre 120/70 17

rear tyre 160/60 17

 

New front tyre should have rolling circumference of 1884mm

new rear tyre should have a rolling circumference  1959mm

 

I need to research Honda contacts to see if there is a way to run ABS on dyno, as all bike have ABS now, there must be a cheat ?

 

Done some research, Honda  workshop box disables ABS to do dyno run.

 

Healtech do a box for £65, that takes the ABS out.

 

I have now  proved it on dyno, works perfectly in all modes D,S,AT,MT.

 

Now  taken complete ABS off the bike and still working perfectly.

 

Will report about dyno work, don't know how you show videos or photos sorry.

 

Thanks for  all your help and information.

 

Nick Turner

 

 

 

 

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jeremyr62

Well done that man. Please keep us informed how it performs. 

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SteveThackery

So, Nick, why are you putting it on a dyno anyway?  Sorry if I missed that bit in the discussion!

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spaaz

Hi, Steve. I had to put it on the dyno because I have taken off all the road gear, inc ABS. air box,+ race exhaust.

I haven't ridden a bike for 17 years since head butting a wall at Kirkmicael  in the 2004 TT 1000 Production race. 

Due to my brain injury, I have no co-ordination and my left ankle is fused.

So the only way for me to ride was an auto bike, only on the track.

Hence Project NC750.

I have saved a lot of weight, now cutting off the heavy rear sub frame. Shortening original tank turning it around over the engine, to get more weight  forward.

Making a alloy seat mounting bracket .

Fitting CBR600RR tank cover and race seat.

Dropped the front forks 35mm to quicken the steering up and get more weight on the front.

Might try to jack the back up a little, to get the ground clearance back ?  i've lost from dropping the front down.

Then we will try a small track day at a Kart circuit and see if I don't die.

I have about 50hp at  the moment, no more is required.

More weight off would be nice, but I think the engine is heavy.

Mag wheels next maybe.

Thank you to the  Forum for all you help and advice.

Alive and laughing.

Nick Turner

Ashburton, Devon

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Johnnie Mototrans

I think we need some pictures of your handiwork Nick.

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Andy m

Great news it's coming on. Looking forward to photos. 

 

The rear is sending 50 teeth past the sensor for every 1959mm travelled. 

This is  1.03 revolutions for the front so 62 teeth going past. 

 

This seems backwards, I'd have put fewer teeth on the faster turning smaller wheel, but can be tuned out. Seeing 50 (front sensor to rear polewheel) when expecting 62 will certainly log a fault. 

 

Electronics to multiply a sine wave frequency by 1.24 is not rocket surgery . The healtech box is generating believable false signals , probably waves from the alternator suitably modified by the RPM. A dyno could include an Oscilloscope type circuit. 

 

On a dyno with a conventional gearbox either just pull the ABS fuse or accept it'll bring the light on. Most sensor faults will clear after keying off and riding above 7 kph with both sensors working. The only bikes I'd expect to be awkward with possible latching warning lights might be BMW. 

 

Andy

 

 

 

 

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