Never asked a question till now.......... | GTAMotorcycle.com

Never asked a question till now..........

kneedragger88

kneedragger88

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In all my years on this forum I have answered many tech questions but never asked one so here goes.
Just reading up on the 2012 R1 with its updated traction control system. It would appear that the engineers have decided to save weight by not adding rear wheel speed sensors to the bike. Rather they have used a countershaft speed sensor which measures the rear wheel speed at the output shaft of the engine.
Sooooooo seeing as TC uses front and rear wheel speeds to determine rear wheel spin allowing the CPU to cut power/ignition/fuel to counteract the spin bringing the wheels back inline. Now assuming that you never change the final gearing this is absolutely possible. However what happens when you race the bike and change ratios for different tracks? This would make the TC useless and would likely have to be shut off completely.
Maybe I am missing something here but something smells wrong. Enlighten me please maybe its just too much turkey making my brain slow (well slower than usual anyway :) )
 
In simplified terms - the system senses a sudden jump in engine rpm. There are many systems like this in racing. Kawasaki uses it also. So if you were on the throttle (hard or constant) at say 10K rpm, and all of the sudden the ECU sensed that rpm jumped 500rpm (or was about to), in a split second it would know that that is too quick of an acceleration to be possible with sufficient grip levels - therefore a physically too high/fast jump in rpm at a particular throttle opening/lean angle would be considered a slide. Obviously the ecu computes this hundreds of times per second, but that's the jist of it. Gear ratio's do not matter with this system - it senses spikes in rpm.
 
Ok I did consider something of the like........but then why the need for the front wheel sensor which is still in place? Would the computer not just sense the rear wheel the same without the front input? Also highsides (which is one of the things that they are trying to avoid) are generally (not always) caused by a gradual wheel slide that hooks up, at least on large bikes. Not a sudden spike but rather a slow climb and if that happens the ONLY fix is hard throttle input to keep the tire spinning until somewhat inline with the front. The system as described would not #1 stop it from happening and #2 allow the rider to save it with a healthy dose of wheelspin/throttle. Again I am certain the engineers are smarter than me but just not getting it. Hell even MotoGP and WSB use both smells like economics more than an improvement.
 
According to my research, the R1 indeed has a rear wheel sensor.

"The new R1 uses a wheel-speed sensor on the front and rear wheel and measures the difference in speed between the two. The important difference between the new R1's traction control and that of the BMW S1000RR, Kawasaki ZX-10R and Aprilia RSV4 APRC SE is that the R1's system is reactive. Unlike the others, it won't take any action until the rear has started to 'spin' faster than the front. It has three ways of preventing the rear wheel spinning, sliding and ultimately causing a highside: 1. The ignition is retarded by the ECU 2. The volume of fuel being injected into the cylinder is altered 3. The degree of throttle opening is reduced.

Read more: http://www.visordown.com/road-tests...yamaha-yzf-r1-review/19651.html#ixzz1hbJMYTOp"



You're welcome.​



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According to a review in Cycle Canada, to change sprockets you need to buy a Genuine Yamaha Technology Racing kit ECU.
 
SunnY S said:
According to my research, the R1 indeed has a rear wheel sensor.

"The new R1 uses a wheel-speed sensor on the front and rear wheel and measures the difference in speed between the two. The important difference between the new R1's traction control and that of the BMW S1000RR, Kawasaki ZX-10R and Aprilia RSV4 APRC SE is that the R1's system is reactive. Unlike the others, it won't take any action until the rear has started to 'spin' faster than the front. It has three ways of preventing the rear wheel spinning, sliding and ultimately causing a highside: 1. The ignition is retarded by the ECU 2. The volume of fuel being injected into the cylinder is altered 3. The degree of throttle opening is reduced.

Read more: http://www.visordown.com/road-tests...yamaha-yzf-r1-review/19651.html#ixzz1hbJMYTOp"



You're welcome.​




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Click to expand...

Not according to this months RRW.
"Yamaha's traction control system uses a front wheel spees sensor and a sensor at the transmission output shaft to monitor rear wheel speed.
For (a traditional) rear wheel speed sensor we (would) have to put weight on. YZR-R1 Project leader Shin Yokomizo told Road Racing World. Supersport motorcycles need a lightweight feeling, so if we weight on the rear wheel we reduce performance. Yokomizo added that using the output shaft sensor saves weight and cost and works just as well as a system using a traditional rear wheel speed sesor.
The Yamaha's ECU constantly measures and compares front and rear wheel speeds as the primary method of detecting rear wheel slip, but the ECU also takes into consideration throttle position,gear position, engine speed and the rate at which the throttle position and engine speed are changing to further evaluate traction."

So by reading its critical to have accurate rear wheel reading (makes sense) and that cannot be achieved if rear gearing is changed as the ECU has no reference to calculate from.

Having to buy a Kit ECU makes much more sense. Save a buck on the street bike and stick another one in the racer. Street guys had better take notice before swapping their street gearing as it will play hell with the stock ECU and make their fancy *** tracktion control useless.

O'ya Your welcome :)
 
I would assume they could get around this by simply programming the ecu to read both F&R sensors, regardless of where on the bike they were located, and comparing the voltage spikes put out by both. If the rear where to see a sudden jump of 1.5 volts, and the front didn't, maybe the ecu would presume a spinning rear tire would be culprit and pull timing or pulse width?

Just guessing here
 
I suppose that could be possible but it would have to reset every time the bike stops and have a cycle time when you start moving again to compensate for a higher voltage that say a shorter gear ratio would provide all the time. Damn I am getting old. I remember reverse polarity 6V systems with Zeener diodes all this 'puter stuff makes my brain hurt.
This still smells of a cost savings. If you weigh the wheel sensor and subtract the countershaft sensor I cant imagine its more than a couple grams. Take off the goofy ram air reflectors and your even. I know, I know unsprung weight but sheeesh this system just creates problems that didnt need to be created.
 
If they were cheap buggers with their programming, you'll have to go in with a diagnostic tool of some sort and change the calibration. If they were really nasty, the only way this is possible would require the race-kit ECU (seems to be the case). If recent history is any prediction of the future, in very short order, someone will figure out how to re-flash the stock ECU to fix this anyhow - and given that the R1 in production form is horribly restricted at the ECU anyways, they already need a re-flash. Costs a few hundred, though. And none of this is any help if you change gearing trackside, which happens all the time with a track/race bike. Very bad move if this is the case.

If Yamaha were smart about it, they'd put in some very straightforward adaptive logic in the ECU. If road speed is within a certain range and the brakes are not being applied and engine load is less than a certain amount then record the ratio of front to rear wheel speeds, do this a few times in a row until several calculations give the same result within a small percentage of error, and use that in all subsequent calculations. Stuff like this is done all the time in automotive, and this would be a dead simple one to do.
 
kneedragger88 said:
This still smells of a cost savings. If you weigh the wheel sensor and subtract the countershaft sensor I cant imagine its more than a couple grams.
Click to expand...

The really smart thing to do is actually to eliminate the countershaft speed sensor and use only the wheel speed sensor.

Only thing the countershaft speed sensor does normally, is operate the speedometer (incorrectly, if you have changed the final drive ratio). If you have the wheel speed sensor then you have the speed - and the final drive ratio won't mess it up.

The automotive folks figured this out a few years back. Speedo always used to be operated from a sensor in the transmission. ABS came from the wheel speeds. Eventually someone smart figured out that they didn't need the sensor in the transmission any more ... It requires the control modules to communicate with each other, but that's a given these days anyways, a CANbus / DeviceNet network saves a ton of wiring and can make everything play nice together. (On my VW the volume of the turn signal clicker varies with road speed and the wipers automatically go to a slower speed when you stop the car, stuff like this is dead simple to do when everything communicates over CANbus)
 
OFFICIAL YAMAHA PRESS RELEASE :

"The system constantly monitors sensors in the front and rear wheels, and when any rear wheel spinning is detected the system alerts the ECU which instantaneously adjusts the degree of throttle opening, fuel injection volume and ignition timing."​



Every single review I read of this bike says Yammie had to add a front wheel sensor to make the TC work, in addition to existing sensors including a rear wheel sensor as the bike is controlled by fly-by-wire throttle.

They all go on to say that the system works by comparing the front wheel speed with the rear wheel speed sensors, and based on pre inputted values, senses if the rear tire is slipping.

One review I did read, said that the lack of gyro and lean sensors were solved with a system somewhat like Ken describes in his post. This was done to "save weight" but in reality, an unnamed Yamaha engineer said they had to cut costs citing "finite resources" available to them.

Sooooo, does it have a rear wheel speed sensor or not? :)
 
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It wouldn't take too many extra lines of code to have the bike take a new sample every time the bike is started and starts rolling. At a low RPM at lower speeds it would be fairly simple.

If the pulse ratio is programmed into the ECU and is not something you can change, that's pretty dumb.
 
The how-it-works articles are all well and good, but they don't address the issue central to this discussion ... whether it has an actual rear wheel sensor or a sensor on the countershaft sprocket, or both, and if it only has one on the countershaft sprocket, what happens if you change the final drive gearing. None of the photos that I could find have sufficient clarity to show whether there is a rear wheel speed sensor.
 
Brian P said:
The how-it-works articles are all well and good, but they don't address the issue central to this discussion ... whether it has an actual rear wheel sensor or a sensor on the countershaft sprocket, or both, and if it only has one on the countershaft sprocket, what happens if you change the final drive gearing. None of the photos that I could find have sufficient clarity to show whether there is a rear wheel speed sensor.
Click to expand...

Thats what I was asking Brian. Anyway as it would appear Yamaha wants to sell you a kit ECU that likely allows you to plug and play gear changes. Just seems very unnecessary is all. You know those damn engineers just like to make things difficult :p
 
I've read numerous articles. Many from the official launch of the R1 with Yammie reps present.

I'd like to think if this was a totally new type of system, more noise and discussion would have been made about it?

I've never heard of a system that works without a rear wheel sensor, and find it hard to believe that adding a RWS would add significant cost and weight. Esp, since the Yamaha system is a budget system anyway.
 
This month's Cycle Canada provides the answer: "... Changing the rear sprocket by more than two teeth or the countershaft by more than one would put the TCS into fault mode and disable its function. If you want to access the full range of sprockets that a racer requires, it's necessary to spring for the GYTR kit ECU."

That sucks.
 
So it sounds like the product managers tasked the engineers with coming up with a new source of revenue (optional race ECU) rather than any upfront costs savings. Bastids.
 
The Bazazz system does not use wheel speed sensors

SunnY S said:
I've read numerous articles. Many from the official launch of the R1 with Yammie reps present.

I'd like to think if this was a totally new type of system, more noise and discussion would have been made about it?

I've never heard of a system that works without a rear wheel sensor, and find it hard to believe that adding a RWS would add significant cost and weight. Esp, since the Yamaha system is a budget system anyway.
Click to expand...
 
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