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Discussion Starter · #1 ·
Does anyone know what EXACTLY putting it into 4WD low does?
Is it just a software thing?
I have seen video and on websites where people say it just keeps it in first gear.
That seems unlikely though.


Sorry if this has been asked or said before but I could not find anything.
 

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Discussion Starter · #2 ·
A Jeep video states "Driving in 4WD Low on dry, hard surfaced roads may cause increased tyre wear and damage to driveline components."
This sounds to me like it has diff locks, but we know it does not.
 

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I was told it puts the transmission into the lowest possible gear ratio for maximum torque, and driving faster than 15mph with it in Low could damage the transmission. I would think its meant to be used if you were climbing small boulders and ledges.
 

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As far as I know, 4WD Low locks the rear driveshaft and rear differential providing power to both the front & rear wheels. Neither differential will lock, but the brake(s) will clamp down on any wheel that is spinning forcing the power to the other wheel on that "axle." It's an electronic version of a real limited slip or locking differential.

And for the Trailhawk, it will start in first gear if Rock mode is selected (The Trailhawk normally starts in 2nd gear unless you floor it and then it quickly shifts to first).
 

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It does indeed just keep it in 1st gear. In the 9 speed auto, most of the time you're starting in 2nd gear from a complete stop. That's because 1st gear is crazy low, and you zip through 1st in no time. So for the TH, it's programmed that in "4 Low" it just holds it in first gear, only shifting to second if it's needed.

If you have the 9 speed, come to a complete stop on the road then use the Auto Stick to shift. You'll notice that it starts at 2nd gear. Now bump it down and you can take it into first. Hit the gas and you'll feel that Trailhawk 4 Lo gearing.
 

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Discussion Starter · #6 ·
It does indeed just keep it in 1st gear. In the 9 speed auto, most of the time you're starting in 2nd gear from a complete stop. That's because 1st gear is crazy low, and you zip through 1st in no time. So for the TH, it's programmed that in "4 Low" it just holds it in first gear, only shifting to second if it's needed.

If you have the 9 speed, come to a complete stop on the road then use the Auto Stick to shift. You'll notice that it starts at 2nd gear. Now bump it down and you can take it into first. Hit the gas and you'll feel that Trailhawk 4 Lo gearing.

Thank you.
Where did you find this information. I cant find anything anywhere.
 

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Discussion Starter · #8 ·
I was told it puts the transmission into the lowest possible gear ratio for maximum torque, and driving faster than 15mph with it in Low could damage the transmission. I would think its meant to be used if you were climbing small boulders and ledges.
The handbook says 4Low can be released between 0 and 120kph (75mph).
 

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syzygy,

The official Jeep brand website provides a 4x4 FAQ and glossary that you may find helpful. It does a nice job of thoroughly describing 4WD low and other 4x4 features: http://www.jeep.com/en/4x4/faqs/.

Per the website's definition: 4WD low-range is a mode specifically designed for temporary use when additional traction and maximum pulling power is desired. Front and rear driveshafts are locked together and engine power is sent through another set of gears to multiply torque. Avoid attempting to engage or disengage Low Range with the vehicle moving faster than 2 to 3 mph (3 to 5 km/h) and do not use this mode for normal driving.

Hope this helps!
 

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Discussion Starter · #10 ·
Thanks Jack. Am I right in thinking that 4WD Lock locks the disconnect only and 4WD Low locks the centre differential as well?
Interesting to hear that there are separate gears involved.
 

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Thanks Jack. I am just a bit worried that the 4Low that site refers to is the Cherokee.
Okay, I spoke with some of the brand folks regarding this and they said your thinking on this is correct. 4WD Lock locks the disconnect and puts the system in 4WD all the time. 4Low is only available on the Trailhawk and provides the low range gear/ratio for off-roading or other needs.
 

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It does indeed just keep it in 1st gear. In the 9 speed auto, most of the time you're starting in 2nd gear from a complete stop. That's because 1st gear is crazy low, and you zip through 1st in no time. So for the TH, it's programmed that in "4 Low" it just holds it in first gear, only shifting to second if it's needed.

If you have the 9 speed, come to a complete stop on the road then use the Auto Stick to shift. You'll notice that it starts at 2nd gear. Now bump it down and you can take it into first. Hit the gas and you'll feel that Trailhawk 4 Lo gearing.
So, I don't have the TH so I apologize if I sound confused or if I'm talking out my arse, LOL...

I have the Latitude and mine certainly starts in first gear from a complete stop. It is seriously the quickest first gear I've ever seen, normally upshifting before it even reaches 15mph - and its pulling some serious RPMs by that time.

It has hella-amounts of torque in first gear. I can see keeping it in first gear and locking 4WD almost feeling like my '98 XJ's 4LOW

Now, if I dial into Snow mode it starts out in second gear, which sorta makes sense as you don't want all that torque with ice and snow under your wheels.

I assumed the TH had different gearing for its 4LOW feature... Some extra feature in the tranny, or the diff, or the transfer case, or the programming, or some mixture of all of the above? Is this not the case?
 

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Discussion Starter · #15 ·
I am still unsure about it all. Does the trailhawk have a centre differential?
The limited with auto box has 4low so not only on trailhawk.
If there are no diff locks why would 4low damage the tyres or drivetrains?
Why can Jeep (Fiat) just not publish the EXACT specs of the AWD system?
 

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The Trailhawk does have different gearing than the other automatic Renegades. Its 4.334 final drive ratio compares to 3.734 in the other automatic models. The 4.334 is what gives the Trailhawk the 20.4:1 crawl ratio in first gear. 3.734 final drive equates to a 17.2:1 crawl ratio in first gear for the other models with automatic.

Manual transmission cars get the 4.334 final drive ratio too, but first gear is not as low. The crawl ratio is 18.1 on manual transmission cars.

There is no center differential in the Trailhawk or other models. The 4x4 system is the same on all the Renegades (software programming is likely different).

There are no differential locks, but activating 4WD lock will lock (at least) one front wheel to (at least) one rear wheel. Turning sharply can force wheels to turn at different speeds putting stress on the 4WD system if driven on dry roads for too long.

Hope this helps. :D
 

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The Trailhawk does have different gearing than the other automatic Renegades. Its 4.334 final drive ratio compares to 3.734 in the other automatic models. The 4.334 is what gives the Trailhawk the 20.4:1 crawl ratio in first gear. 3.734 final drive equates to a 17.2:1 crawl ratio in first gear for the other models with automatic.

Manual transmission cars get the 4.334 final drive ratio too, but first gear is not as low. The crawl ratio is 18.1 on manual transmission cars.

There is no center differential in the Trailhawk or other models. The 4x4 system is the same on all the Renegades (software programming is likely different).

There are no differential locks, but activating 4WD lock will lock (at least) one front wheel to (at least) one rear wheel. Turning sharply can force wheels to turn at different speeds putting stress on the 4WD system if driven on dry roads for too long.

Hope this helps. :D
^ ^ ^
This
 

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Discussion Starter · #18 ·
The Trailhawk does have different gearing than the other automatic Renegades. Its 4.334 final drive ratio compares to 3.734 in the other automatic models. The 4.334 is what gives the Trailhawk the 20.4:1 crawl ratio in first gear. 3.734 final drive equates to a 17.2:1 crawl ratio in first gear for the other models with automatic.

Manual transmission cars get the 4.334 final drive ratio too, but first gear is not as low. The crawl ratio is 18.1 on manual transmission cars.

There is no center differential in the Trailhawk or other models. The 4x4 system is the same on all the Renegades (software programming is likely different).

There are no differential locks, but activating 4WD lock will lock (at least) one front wheel to (at least) one rear wheel. Turning sharply can force wheels to turn at different speeds putting stress on the 4WD system if driven on dry roads for too long.

Hope this helps. :D
They do not claim 4 lock could damage the tyres and drive train. Only 4 Low. If it is only holding lower gears longer why would it damage anything?
 

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As said above the only difference between a TH driveline and other Renegades with slush boxes is the lower final drive ratio. The final drive moves the ratios of all nine transmission gears down or up depending on its gearing. The TH and non-TH auto trans has exactly the same gears. The TH lower final drive ratio pulls first gear down low enough to render it somewhat useless for anything other than crawling where that same gear is usable on the street with the other final ratio. The only function of the "low" setting in the TH is to lock the trans in first gear so that it can creep.
My 1.4t can "crawl" at 8 mph in first gear just like a TH when dialed into "low". It actually does fantastic at climbing up pretty much anything at that range as its right in its optimal (and higher than a 2.4's) torque band. If I were able to find a set of different differential gears for it I could pull that 18:1 ratio closer or even beyond the 20:1 of the TH. Since sixth gear is pretty useless below 80 mph anyway I may actually do this someday. That would bring first gear closer to an actual crawl gear and sixth down to a more usefull rpm/mph range.
The one difference may be the TH's ability to lock up a spinning wheel to transfer torque. I'm not sure the 1.4T driveline can do this. As soon as my recovery hook arrives and I can take the Jeep to a real off road park I intend to find out.
-Jason
 

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its basically for scaling or "crawling" uneven terrain like a rocky hill it gives maximum traction and controls the wheel spin something u cant do in the normal drive gear so u don't go to fast and lose traction not something for everyday driving or bad weather as its not made to go fast when engaged that's what normal 4x4 lock mode is for though it will spit power depending on what setting u chose on the dial usually slippery surfaces like snow more power in the front is wanted where on mushy or soft surfaces like mud or sand more power in the rear is wanted so u don't get bogged down
 
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