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Originally Posted by falconion I am not sure of the speed at which the XUVs AWD lock gets disengaged. I have taken it upto the speed of 60-70 without the AWD lock getting disabled. I did not want to take it up higher than that. |
The LED staying on does not indicate the status on power split or whether the system is engaged, it only says you have asked for the lock. The light would stay even at 200kph.
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Originally Posted by general_neo Seriously? They aren't full time AWD? i was assuming that they are full time when they say AWD
... Otherwise they are 4WD.... |
No these are Part time, Torque on demand systems, not full time AWD.
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Originally Posted by Tanveer_2558 XUV AWD is full time AWD, Normally it will give out 60% Power in the front and 40% Rear, Pressing the AWD lock button will split the power 50% in both front and rear tyres.
Once i had just pressed the AWD lock button after starting and the engine just to check if everything is working fine, I forgot to disable it before starting to drive and it was on all the time and i had crossed 100 Kph, Later on when i saw the button it was still lit up. |
No it is not full time AWD, it is part time Torque on demand AWD, not full time with center differential.
The same Borg Warner ITM was used for last gen Hyundai Santa Fe, and AFAIK for Tucson and Kia crossovers. I had done my research before buying the car.
Here is the description on how this system works:
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Hyundai's new system uses a computer-controlled clutch mechanism mounted in front of the rear axle to engage the drive. It is a Borg Warner system that can provide up to 99% of the torque to the front wheels, but automatically diverts up to 50% of the torque to the rear wheels when needed. The driver can push a button on the dash as an input to the computer, commanding it to "lock" the torque transfer at 50/50 for getting out of slippery parking spots in winter or ploughing through some soft sand. While there is no low range in the Santa Fe all-wheel drive system, it is more than capable of handling many off-road excursions.
Because the torque transfer to the rear wheels is variable, a dependable, durable clutch mechanism is needed that can be instantly engaged. To do this, the computer monitors wheel speed, accelerator pedal movement and steering inputs. When 4% or more front wheel slip is detected, the rear axle starts to engage. It can also anticipate the need for additional traction and engage the AWD system when the driver accelerates the vehicle. Another feature is it can disengage the rear axle during ABS events to optimize ABS stopping.
The computer controls a large solenoid coil in the clutch housing. When energized, the solenoid pushes against a multi-plate clutch, which in turn holds a washer-like plate from turning. Ramps and balls between this plate and a second plate cause the two plates to be forced apart, placing pressure on a second larger multi-plate clutch that connects the driveshaft to the rear axle. The path of torque is complete and the rear wheels drive. A button on the dash can lock the clutch to provide 50% torque to the rear wheels, but this only occurs below 35 kph. Above that speed, the computer pulses the solenoid to disengage the clutch mechanism, but it will automatically engage it again when vehicle speed lowers.
Finally, the system monitors steering wheel angle. Turn the steering wheel, such as when parallel parking or turning a tight corner and the computer will decrease the torque applied to the rear wheels to there is no driveline binding during the turn.
Computer controls, electric solenoids and data communication between computers are all used to provide smooth traction regardless of the driving conditions and optimize fuel economy too. That's modern all-wheel drive.
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Originally Posted by falconion Nomenclature is easily confusing.
Full-time AWD or Full-time 4WD (i.e. Rexton): All four wheels get torque transferred to them all the time regardless of the terrain. |
I hope you know Rexton comes with 2 different AWD systems:
The top of the line
RX7 Automatic gets a full time AWD system, the center differential cannot be locked for 50:50 split, has no low range. Intended for road usage, not good off road.
RX5 manual, gets a Torque on demand type, part time AWD system based on Rear wheel drive system, but this also gets Low range gearing reduction with 50:50 lock. Not intended for road usage, but works great off the road. The torque on demand system is old type operated through viscous couplings and not through the clutch pack(like the one in XUV), as a result it is not as seamless and i have observed a few jerky false actuation's(like when accelerating while taking a tight U turn).
The rally Mahindra Super XUV, has a work around for this AWD system which gets disengaged at speed. They got a cheat device designed from Racedynamics, which sends false data to AWD system to keep it engaged. The downside is the AWD clutch pack lasts only for a short period.
And it's not only this AWD system which gets disengaged at speed, most others at this price point also do, example Renualt Duster and Skoda Yeti. All these compact AWD systems send little to Zero power to the rear axle at speed usable for cornering.