Raptor 4A question

[JimJa]

How does 4A work?

Originally when Ford produced a transfer case with 4A 10 years or so ago, it was said 35% of the torque is sent to the front axle and as the rear wheels slipped torque to the front was progressively increased.

I recently "tested" the system on my Raptor on a section of ice on the road in front of my house. It seemed when in 4A the rear wheels had to slip before the transfer case engaged the front axle. It didn't seem to take much slippage, but there didn't appear to be any engagement unless there was rear wheel slippage. As expected when using 4H this short delay did not appear to be there.

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[bill_AUS]

Mechanically it's a multi disc wet clutch in there and the PCM can modulate the pressure on the clutch pack to vary the engagement %. Not sure what the logic in it is, but generally in the Everest I've driven a fair amount with the same transfer case, it sends torque forward while you're accelerating, then backs off while cruising or decelerating.

 

[ducktapeonmydesk]

In 4WD mode, the transfer case system operates continuously without requiring any driver input. The AWD module constantly monitors vehicle conditions and automatically delivers torque to the front driveshaft. This is achieved using a multi-plate clutch pack within the transfer case, which regulates torque transfer to a chain drive connected to the front driveshaft. If the system detects wheel slip or a handling event, the AWD module activates the transfer case actuator, which applies torque to a ball ramp cam mechanism. This mechanism generates axial force to engage the clutch pack.

 

[sikedsyko]

My wife's Bronco Sport uses a clutch based AWD system to power the rear wheels. On the dash they have a display that shows you what power split the system is commanding. I wish they did that in the Ranger, so I could get a better understanding of when the system is engaging and how much.

 

[AlpineBike]

My wife's Bronco Sport uses a clutch based AWD system to power the rear wheels. On the dash they have a display that shows you what power split the system is commanding. I wish they did that in the Ranger, so I could get a better understanding of when the system is engaging and how much.

Even my awd Transit van shows me this.

It baffles me that my Raptor doesn’t!

 

[ducktapeonmydesk]

Here is a video on how that clutch works.

 

[Jason B]

IIRC, 4A (4 auto) is not the same as AWD.
4A puts it in 4WD if slippage occurs in the rear axle.
AWD is All Wheel Drive and has varying torque/power to front and rear at all times.
But maybe Raptor is a combo of the two?

 

[JustNick]

Even my awd Transit van shows me this.

It baffles me that my Raptor doesn’t!

You can activate that screen with forscan, I typically drive with either that on or the intake air temps. I've found it's a pretty even split front to back on easy acceleration, then biases to the rear above 35mph. At least according to that screen, that's what it's doing

 

[ducktapeonmydesk]

IIRC, 4A (4 auto) is not the same as AWD.
4A puts it in 4WD if slippage occurs in the rear axle.
AWD is All Wheel Drive and has varying torque/power to front and rear at all times.
But maybe Raptor is a combo of the two?

4A on the Raptor can vary the torque output to the front wheels.

 

[joordan]

there is definitely electronics governing the clutch cause when cruising you are in 2H and as soon as you accelerate it goes in 4H, without any slippage triggering it.
pure mechanical clutch or even torsen C diff lock works based just on mechanical axles rotation

 

[ducktapeonmydesk]

there is definitely electronics governing the clutch cause when cruising you are in 2H and as soon as you accelerate it goes in 4H, without any slippage triggering it.
pure mechanical clutch or even torsen C diff lock works based just on mechanical axles rotation

Can I get a source on this?

 

[joordan]

Can I get a source on this?

about which part?the one on how the ranger have it implemented is based on pure experience, just test it. the part on mech lock is based on any mechanical engineering book

 

[ducktapeonmydesk]

about which part?the one on how the ranger have it implemented is based on pure experience, just test it. the part on mech lock is based on any mechanical engineering book

That 4H turns on under acceleration when in 2H mode.

 

[joordan]

The Advanced 4WD system uses an electromechanical transfer case with a multi-plate clutch pack to distribute power between the front and rear wheels, varying the torque split from 0:100 percent to 50:50 percent. The system’s default drive nominally aims for 40:60 front to rear split but it will send more torque to the front under hard acceleration from a standstill to minimise wheelspin. It will also adjust torque if it senses the vehicle is sliding or the rear wheels are spinning.

The system also remains locked when you switch the engine off, which means the handbrake and park pawl system work on all four wheels on shutdown.

https://media.ford.com/content/ford...t to 4A (4WD,calibrations for each drive mode.

 

[ducktapeonmydesk]

The Advanced 4WD system uses an electromechanical transfer case with a multi-plate clutch pack to distribute power between the front and rear wheels, varying the torque split from 0:100 percent to 50:50 percent. The system’s default drive nominally aims for 40:60 front to rear split but it will send more torque to the front under hard acceleration from a standstill to minimise wheelspin. It will also adjust torque if it senses the vehicle is sliding or the rear wheels are spinning.

The system also remains locked when you switch the engine off, which means the handbrake and park pawl system work on all four wheels on shutdown.

https://media.ford.com/content/fordmedia/img/im/en/news/2023/09/27/the-intelligent-engineering-behind-ranger-and-everests-advanced-.html#:~:text=When set to 4A (4WD,calibrations for each drive mode.

That's when in 4A, not in 2H.

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