[VW2010]

Question - If the ABS module itself "corrects" the wheel lock up without the brake pedal being depressed, how does it differ from traction control?

My take is traction is needed while accelerating while ABS is needed for braking though principally they are same trying to control wheel rotation to maintain stability and avoid skidding.

Traction control basically uses abs sensors to monitor wheel spin and may even apply brakes if needed to help the wheel gain traction.

[batterylow]

ABS and TC have the opposite working principle.

ABS:
It uses the wheel speed sensors to detect if a wheel is locked during braking and releases the brake so that the wheel achieves traction.

TC:
It uses the wheel speed sensors to detect if the wheel is slipping during acceleration and applies the brake so that the wheel achieves traction.

[ebonho]

Originally Posted by Sutripta

Talking of the car and bike? Or car only?

Truck.

Replicable?

Don't know. Re-challenge pending.

Originally Posted by VW2010

Traction control basically uses abs sensors to monitor wheel spin and may even apply brakes if needed to help the wheel gain traction.

Originally Posted by batterylow

TC: It uses the wheel speed sensors to detect if the wheel is slipping during acceleration and applies the brake so that the wheel achieves traction.

I did not know/realise that traction control involved brakes. I always thought it involved some form of modulation of how the power was being laid down to the wheels.

[batterylow]

Originally Posted by ebonho

I did not know/realise that traction control involved brakes. I always thought it involved some form of modulation of how the power was being laid down to the wheels.

Your idea is correct, the brakes being just one of the factors that can be modulated to achieve traction.

It can also be achieved by other means, viz throttling the fueling etc

[sam_sant2005]

Originally Posted by batterylow

Your idea is correct, the brakes being just one of the factors that can be modulated to achieve traction.

It can also be achieved by other means, viz throttling the fueling etc

A Simple explanation for TC is - sensors check 'relative' rotational speeds on each tyre and apply the 'control' whenever required (yes braking) to ensure traction on all four wheels.

Ideal ABS logic works on individual wheel.

[Cyrus_the_virus]

Originally Posted by ebonho

So what exactly was the "ABS type" judder I felt and sound I heard in my case? Since the brake was not being pressed, was it the ABS module just "blank firing" the brakes with no effect on the whel lock? Or as Viju explained, was it the ECU cutting torque in milisecond bursts?

My best guess would be, you actually had the break pedal pressed. You see, on the 390, there is very little leeway on the pedal, which mean you are almost always slightly pressing the pedal if you aren't real careful. Especially in a quick panic reaction, it is only natural to sometimes slightly dab on them brakes without realizing.

[MavericK46]

Originally Posted by sam_sant2005

A Simple explanation for TC is - sensors check 'relative' rotational speeds on each tyre and apply the 'control' whenever required (yes braking) to ensure traction on all four wheels.

Ideal ABS logic works on individual wheel.

Originally Posted by batterylow

ABS and TC have the opposite working principle.

ABS:
It uses the wheel speed sensors to detect if a wheel is locked during braking and releases the brake so that the wheel achieves traction.

TC:
It uses the wheel speed sensors to detect if the wheel is slipping during acceleration and applies the brake so that the wheel achieves traction.

To add to this..

Braking and/or shutting down one or more cylinders (by retarding the sparking or cutting off fuel supply).
Needless to say that the simpler systems rely solely on engaging brakes and the more complex ones resort to cutting off ignition to individual cylinders.

Cheers !

Sundar

[Cyrus_the_virus]

Originally Posted by ebonho

As mentioned earlier in case you missed it, my foot was nowhere near the brake pedal. Like many newbies (and some seasoned folk too) I do not ride either the brake or the clutch. And there was no panic - quite the opposite (in terms of absent-minded somnolence). Hope that re-clarifies .....

In that case it has nothing to do with ABS then.

I realize you are probably very well versed with ABS.. but for the sake of general discussion; You see the function of ABS is to let go of the wheel for a few milliseconds to prevent the lockup when you are actually holding it down.
So, here is the case for why ABS doesn't interfere when you aren't holding the brakes.

Imaging you are just riding and not doing anything with the brakes and your wheel is locking up.. how will ABS stop the lockup? The wheel is already locking up and the brake pads are not holding the disk, so if ABS engages and actually ends up holding the disk, it would only make the lockup worse. You get the point I'm trying to make yeah?

If you experienced ABS interference without holding down the brake, check on the rear disk clearance for the brake pads. We have had a few cases in the past where the real brakes was at full stop even without any input on the pedals and had to manually intervene to have the pads separate from the disk. In this case I would think ABS assumes the brakes are on.. for obvious reasons.

[ebonho]

Originally Posted by Cyrus_the_virus

If you experienced ABS interference without holding down the brake, check on the rear disk clearance for the brake pads. We have had a few cases in the past where the real brakes was at full stop even without any input on the pedals and had to manually intervene to have the pads separate from the disk. In this case I would think ABS assumes the brakes are on.. for obvious reasons.

Would the same not show up in reduced performance (pickup, rolling resistance, top speed) ?

And why only the rear brakes?

[sandeepmohan]

What kind of noise do you get when you hammer the rear brake pedal with abs trying hard to prevent a wheel lock up? The noise I get is more like coming up the gears without using the clutch.

[ebonho]

Originally Posted by sandeepmohan

What kind of noise do you get when you hammer the rear brake pedal with abs trying hard to prevent a wheel lock up? The noise I get is more like coming up the gears without using the clutch.

I never clutchless shift, so cannot say. Its a typical trrrrrrr sound.

[sandeepmohan]

Originally Posted by ebonho

I never clutchless shift, so cannot say. Its a typical trrrrrrr sound.

Neither do I but I know the noise a clutchless shift makes and can relate to the noise of this to the noise I get when I go hard on the rear brakes. Its not a pleasant noise at all. I feel a person riding next to me can hear it as well. Its like a mechanical clunk noise along with resistance from the pedal. The resistance from the pedal being perfectly normal.

[ebonho]

Originally Posted by sandeepmohan

Neither do I but I know the noise a clutchless shift makes and can relate to the noise of this to the noise I get when I go hard on the rear brakes. Its not a pleasant noise at all. I feel a person riding next to me can hear it as well. Its like a mechanical clunk noise along with resistance from the pedal. The resistance from the pedal being perfectly normal.

Yeah, its much louder and closer (and unpleasant) on the 390 compared to the Storme. Probably because you are enclosed in a very nicely sound deadened cabin in the latter. Also probably because in a bike there is the added component of the sound of the clashing transmission as well (chain and sprocket). I am guessing that ABS while good for rider safety, must be putting additional stresses on both of these as the brakes catch and release intermittently.

[Added_flavor]

Originally Posted by sandeepmohan

Neither do I but I know the noise a clutchless shift makes and can relate to the noise of this to the noise I get when I go hard on the rear brakes. Its not a pleasant noise at all. I feel a person riding next to me can hear it as well. Its like a mechanical clunk noise along with resistance from the pedal. The resistance from the pedal being perfectly normal.

I have tried clutch-less up-shifts on all my bikes and believe if done properly they will not make any noise apart from the usual 'click'. The downshifts will be a different story though and I'm always scared to try them.

Coming to the noise from ABS, it is the "trrr" as Doc said.

[VW2010]

The downshifts will be a different story though and I'm always scared to try them.

Most racers upshift without engaging clutch. Its about being at the right rpm and a blip. You can do this in 390 all day and not damage anything.

Downshift is not going to happen when you are at the wrong RPM. This means you may struggle to downshift and there by damage may be few gearing teeth or even the clutch itself.

The minimal sound way i found shifting in 390 was to just keep the gear lever slightly loaded before the actual shift. Toe under the shifter slightly pushing up and then the process of shifting with clutch engaged. Its almost always smooth that way.

I am mostly at over 6k-7k while shifting. Like to have that power band to enjoy the 390