How Freedom Drive I works?

fareastplaza · Feb 18, 2011

I know there is a 'lock' switch. My understand:

When 'Lock' is off: Running as an automatic 4WD. Computer decides when 2WD and when 4WD. It's on demand.

When 'Lock' is on: Force to engage into 4WD. So, 4WD all the time (full time?).

Am I correct?

Additional question. When 'LOCK' is on, will it lock the centre differencial? Can I still take sharp turn on dry pavement?

FreeWillie · Feb 18, 2011

If I understand the Jeep literature correctly, in normal driving the vehicle is FWD. When the ESP (Electronic Stability Program) senses slippage in the front wheels, torque is directed to the real wheels to compensate for the front wheel slippage. In effect this makes the drive system act like an AWD system. When you use 4 Lock the ESP forces a 50/50 torque split between the front and rear drive wheels. This makes the drive system a 4x4. So you have a FWD/AWD/4x4 system all in one!

I'm new to the Jeep so if I have this wrong please jump in and correct this noob.

ETA: Don't know what effect 4 Lock has on dry pavement. I've only got 300 miles on mine and haven't experimented yet.

jepstr67 · Feb 18, 2011

In theory or in actuality?

Jeep.com gives a little video of how it is supposed to work.

Hitzy · Feb 18, 2011

It has open front and rear diffs, and no transfer case....there is a clutch that sends power to the rear, you can drive in circles in 4x4 on pavement for 5 years and not hurt it.

FreeWillie · Feb 19, 2011

Hitzy said:
It has open front and rear diffs, and no transfer case....there is a clutch that sends power to the rear, you can drive in circles in 4x4 on pavement for 5 years and not hurt it.

Thank You! Another question, if you don't mind. The TCS seems to only have 2 positions on the 2011. On/Full Off. Can you confirm that?

I've read a number of posts that suggest there is a On/Partial Off/Full Off for the TCS and that full off is suggested for deep snow and 4 Lock. Any info would be appreciated. Thanks.

MrMischief · Feb 19, 2011

fareastplaza said:
When 'LOCK' is on, will it lock the centre differencial? Can I still take sharp turn on dry pavement?

Yes from what I've learned it's "smart" enough to sense when the speed between two wheels has varied so much that it assumes you are in a tight turn and it goes back to FWD. I tried this on a test drive and that's exactly how it acted. So great for the people who use 4x4 lock on dry pavement (??), but not so good for doing some serious off road work. Seems to be better then anything the competitors bring to the table though.

jepstr67 · Feb 19, 2011

Hitzy said:
It has open front and rear diffs, and no transfer case....there is a clutch that sends power to the rear, you can drive in circles in 4x4 on pavement for 5 years and not hurt it.

That "script" needs to be read by that dry voice who does the Dodge ads! LOL

"Wait. No. There's a monkey."

ColoradoMan · Feb 19, 2011

the real question is if 1 of the front tires is slipping and 1 of the rear tires is slipping and its in 4x4 lock mode, will this stop the other two tires with traction from turning

RHill · Feb 19, 2011

ColoradoMan said:
the real question is if 1 of the front tires is slipping and 1 of the rear tires is slipping and its in 4x4 lock mode, will this stop the other two tires with traction from turning

From my 2008 Owner's Manual, "Traction Control System...If one wheel on a driven axle is spinning faster than the other, the system will apply the
brake of the spinning wheel. This will allow more engine torque to be applied to the wheel that is not spinning. This feature remains active even if TCS and ESP are in either the “Partial Off” or “Full Off” modes. Refer to “Electronic Stability Program (ESP)” in this Section of this manual."

On using 4WD on dry pavement, why do it? I believe that one is asking for trouble. My 2008 owner's manual says, "...Where one or more wheels have wheel spin or if additional traction is needed in sand, deep snow, or loose traction surfaces, activate the 4WD Lock switch by pulling up once and releasing. This locks the center coupling allowing more torque to be sent to the rear wheels..." In a turn, the rear axle will not travel as far as the front axle. On dry pavement, this will add loads to the drivetrain and cause some tire slippage.

Note that it does not say 50/50 torque split. It just locks the driveshafts to the front and rear axle together so that they turn at the same speed. How much torque goes where in 4WD Lock is dependent on how much traction (resistance to turning) each axle has. For instance, if the rear axle is sitting on an ice patch and the front axle is not, it will take very little torque to turn the rear axle at the same speed as the front axle. When the rear axle is off the ice, and both axles have the same traction, then the torque may be split 50/50. If the front axle then encounters an ice patch, little torque will be required to turn it and the rear axle will get more torque than the front axle until it also gets on the ice.

Again, consider what will happen as one goes into, transits, and then climbs out of a muddy stretch. Initially, the front axle will require less torque to turn at the same speed as the rear axle. Then, with both of them in the mud, the torque will probably be about the same, with the Traction Control System controlling slippage from one side to the other of each axle. Then, when exiting the muddy spot, the front axle will have more traction and will use more of the torque.

IMO and FWIW and YMMV.

rocal · Feb 19, 2011

Fareastplaza, I'm going to let you into a secret that I've confessed to once before on this site about two years ago. I was working on a house down in London, about a five hundred mile round-trip for me, during a bad winter. During either the first or second trip down I needed to use the four-wheel drive lock. I forgot to switch it off and that eeny-weeny little light thingy under the speedo doesn't exactly scream at you, does it? I did three more trips with the lock on! Fifteen hundred miles of Motorway (Interstate) and winding country road driving! I sold the vehicle about forty thousand miles later with absolutely no ill effects to the drivetrain whatsoever.

Rocal

Mind you, I believe I did write in about the poor mileage |I got out of my first set of tyres....

goguadi · Feb 19, 2011

RHill said:
From my 2008 Owner's Manual, "Traction Control System...If one wheel on a driven axle is spinning faster than the other, the system will apply the
brake of the spinning wheel. This will allow more engine torque to be applied to the wheel that is not spinning. This feature remains active even if TCS and ESP are in either the “Partial Off” or “Full Off” modes. Refer to “Electronic Stability Program (ESP)” in this Section of this manual."

On using 4WD on dry pavement, why do it? I believe that one is asking for trouble. My 2008 owner's manual says, "...Where one or more wheels have wheel spin or if additional traction is needed in sand, deep snow, or loose traction surfaces, activate the 4WD Lock switch by pulling up once and releasing. This locks the center coupling allowing more torque to be sent to the rear wheels..." In a turn, the rear axle will not travel as far as the front axle. On dry pavement, this will add loads to the drivetrain and cause some tire slippage.

Note that it does not say 50/50 torque split. It just locks the driveshafts to the front and rear axle together so that they turn at the same speed. How much torque goes where in 4WD Lock is dependent on how much traction (resistance to turning) each axle has. For instance, if the rear axle is sitting on an ice patch and the front axle is not, it will take very little torque to turn the rear axle at the same speed as the front axle. When the rear axle is off the ice, and both axles have the same traction, then the torque may be split 50/50. If the front axle then encounters an ice patch, little torque will be required to turn it and the rear axle will get more torque than the front axle until it also gets on the ice.

Again, consider what will happen as one goes into, transits, and then climbs out of a muddy stretch. Initially, the front axle will require less torque to turn at the same speed as the rear axle. Then, with both of them in the mud, the torque will probably be about the same, with the Traction Control System controlling slippage from one side to the other of each axle. Then, when exiting the muddy spot, the front axle will have more traction and will use more of the torque.

IMO and FWIW and YMMV.

when you switch 4wd you actualy set the traction to 50/50.
of course,when the system will feel slipping or any traction difference,it will react accordingly redistributing,but will get back to 50/50.
without the switch on it's pretty much the same thing but goes back to 80/20.
difference is in reaction time,quicker on 4wd on.

RHill · Feb 19, 2011

goguadi said:
when you switch 4wd you actualy set the traction to 50/50.
of course,when the system will feel slipping or any traction difference,it will react accordingly redistributing,but will get back to 50/50.
without the switch on it's pretty much the same thing but goes back to 80/20.
difference is in reaction time,quicker on 4wd on.

If it did this, with the rear axle sitting on ice and the front axle on dry pavement, the torque to the front axle would be dropped to zero, to match the torque to the rear axle, and the vehicle would not move. I believe that the 4WD Lock switch just simply locks the center coupling, as quoted above from my owner's manual, causing the front and rear drivshafts to turn at the same RPM, turning the front and rear axles at the same RPM.

IMO and YMMV.

goguadi · Feb 19, 2011

RHill said:
If it did this, with the rear axle sitting on ice and the front axle on dry pavement, the torque to the front axle would be dropped to zero, to match the torque to the rear axle, and the vehicle would not move. I believe that the 4WD Lock switch just simply locks the center coupling, as quoted above from my owner's manual, causing the front and rear drivshafts to turn at the same RPM, turning the front and rear axles at the same RPM.

IMO and YMMV.

i think you are right,but then how come it works on dry surfaces and at any speed as the maual says?

jepstr67 · Feb 19, 2011

A demonstration video of how it behaves under the many settings would be interesting.
1. AWD (FWD)
2. 4x4 locked 50/50
3. AWD ESP off
4. 4x4 locked 50/50, ESP off
5. AWD ESP full off
6. 4x4 locked 50/50 ESP full off.

miketmx · Feb 19, 2011

I very seldom find a need to use 4X4 lock but I tried it about 2 weeks ago when descending a steep and snow packed slippery ski hill access road. On the hair pin turns I noticed an old fashioned four wheel drift but the Patriot was in control the whole time. I did feel a definite understeer where the turns were not quite as sharp as the steering wheel position would do on a dry road. The Patriot would probably have handled just fine without the 4X4 lock. The owners manual is not very descriptive about ESP but my interpretation is that Partial/Off will disable the throttle governor so that you can spin the wheels when stuck in deep snow. The manual is pretty vague about when to use Full/Off.

jepstr67 · Feb 19, 2011

miketmx said:
I very seldom find a need to use 4X4 lock but I tried it about 2 weeks ago when descending a steep and snow packed slippery ski hill access road. On the hair pin turns I noticed an old fashioned four wheel drift but the Patriot was in control the whole time. I did feel a definite understeer where the turns were not quite as sharp as the steering wheel position would do on a dry road. The Patriot would probably have handled just fine without the 4X4 lock. The owners manual is not very descriptive about ESP but my interpretation is that Partial/Off will disable the throttle governor so that you can spin the wheels when stuck in deep snow. The manual is pretty vague about when to use Full/Off.

Full off also disables the cars computer from using the anti skid system. You know when you are skidding around a corner and the car will put the brake on one wheel to help aim the car where the front wheels are steering? It cuts that system out.

The owner's manual should explain in detail what the systems do, not when to use them. If we know exactly what they do, we can decide when that would work for what we are doing with the car.

ColoradoMan · Feb 19, 2011

RHill said:
From my 2008 Owner's Manual, "Traction Control System...If one wheel on a driven axle is spinning faster than the other, the system will apply the
brake of the spinning wheel. This will allow more engine torque to be applied to the wheel that is not spinning. This feature remains active even if TCS and ESP are in either the “Partial Off” or “Full Off” modes. Refer to “Electronic Stability Program (ESP)” in this Section of this manual."

On using 4WD on dry pavement, why do it? I believe that one is asking for trouble. My 2008 owner's manual says, "...Where one or more wheels have wheel spin or if additional traction is needed in sand, deep snow, or loose traction surfaces, activate the 4WD Lock switch by pulling up once and releasing. This locks the center coupling allowing more torque to be sent to the rear wheels..." In a turn, the rear axle will not travel as far as the front axle. On dry pavement, this will add loads to the drivetrain and cause some tire slippage.

Note that it does not say 50/50 torque split. It just locks the driveshafts to the front and rear axle together so that they turn at the same speed. How much torque goes where in 4WD Lock is dependent on how much traction (resistance to turning) each axle has. For instance, if the rear axle is sitting on an ice patch and the front axle is not, it will take very little torque to turn the rear axle at the same speed as the front axle. When the rear axle is off the ice, and both axles have the same traction, then the torque may be split 50/50. If the front axle then encounters an ice patch, little torque will be required to turn it and the rear axle will get more torque than the front axle until it also gets on the ice.

Again, consider what will happen as one goes into, transits, and then climbs out of a muddy stretch. Initially, the front axle will require less torque to turn at the same speed as the rear axle. Then, with both of them in the mud, the torque will probably be about the same, with the Traction Control System controlling slippage from one side to the other of each axle. Then, when exiting the muddy spot, the front axle will have more traction and will use more of the torque.

IMO and FWIW and YMMV.

I am not sure if this is correct but I think the whole breaking on wheels that are slipping is only on the fd2

WV_Patriot · Feb 19, 2011

Freedom-Drive I™
Jeep® Compass models with a 5-speed manual transaxle or continuously variable transmission feature selectable four-wheel-drive lock. This state-of-the-art electronic system anticipates the need for added traction and responds to wheel-slippage by transferring power to the rear wheels, while modulating rear-wheels to contribute to vehicle stability in cornering situations. The system also saves fuel by operating only on demand when on-road, thereby minimizing power-robbing friction and inertia. Activate the off-road mode by pulling up on the chrome T-handle switch labeled 4WD LOCK in the center console. This mode dictates that the electronic system sends the maximum amount of torque to the rear axle for improved traction.

How FDI works

Freedom-Drive II™
An electronically controlled coupling, which is attached to the rear differential, is the heart of the Freedom Drive II system. The electronic control module processes signals from the wheel speed sensors and the accelerator pedal to determine how much torque to transfer to the rear wheels, then sends an electrical current to the ECC that is proportional to the amount of torque required. Recommended for true off-road situations including steep grades, wheel lift and rock or log climbing, the Freedom Drive II Off-Road Package includes a second-generation continuously variable transaxle with a 19:1 crawl ratio (CVT2L) that engages when the off-road mode is activated.

How FDII works

miketmx · Feb 19, 2011

ColoradoMan said:
I am not sure if this is correct but I think the whole breaking on wheels that are slipping is only on the fd2

I'm sure the anti-skid features of ESP were working when I descended that slippery ski hill access road otherwise I would have fishtailed on those hairpin turns. I think 'brake lock differential' is the feature that distinguishes FDII from the FD1 that we have.

ColoradoMan · Feb 19, 2011

miketmx said:
I'm sure the anti-skid features of ESP were working when I descended that slippery ski hill access road otherwise I would have fishtailed on those hairpin turns. I think 'brake lock differential' is the feature that distinguishes FDII from the FD1 that we have.

I agree. The brake lock will stop any wheels that are slipping and transfer the power to wheels that aren't slipping. It is only found int fd2. With fd1 there is no brake lock so if one wheel on the same axel is slipping the other one won't move. So in theory, if a front and back wheel are slipping the pat would be stuck. Only 2 wheels slipping can stop the fd1 pat.

How Freedom Drive I works?

fareastplaza

FreeWillie

jepstr67

Hitzy

FreeWillie

MrMischief

jepstr67

ColoradoMan

RHill

rocal

goguadi

RHill

goguadi

jepstr67

miketmx

jepstr67

ColoradoMan

WV_Patriot

miketmx

ColoradoMan

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