Does anyone use the "manual" mode on the automatic transmission?

[heamick]

I've owned my Jeep since July and literally just noticed this option last week. I don't recall seeing it mentioned in the manual (yes, I'm a nerd and read the whole thing), but might have glossed over it.

Is there any real benefits to using this, or is it just to feel more sporty? Any dangers with it, or ways that I could mis-use it accidentally and cause damage?

I YES I HAVE SHIFTED this 8 sp alot I think by doing this I programed the trans to go into 7 and 8 gears. going down hill in 6th seemed silly works great.

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[J0E]

When the unit is hunting for a gear, the torque converter is spinning and generating heat.

Exactly, but you still have a torque converter in manual mode. Put it in 4th low range manual, stop, power break. The engine doesn't die because of the torque converter. That's why I added the following above this post:

I use manual mode every time I go beach driving. The transmission does better in manual mode and it doesn't get any hotter than highway driving. At least that's my experience. Driving in loose sand in automatic shift mode seems to be a bad idea since it's too slow to downshift and engine will bog down.

Too slow to downshift means more transmission slipping = more heat.

 

[Carolina Jeeper]

Exactly, but you still have a torque converter in manual mode. Put it in 4th low range manual, stop, power break. The engine doesn't die because of the torque converter. That's why I added the following above this post:



Too slow to downshift means more transmission slipping = more heat.

Exactly. I did notice the trans temp rising steadily when I had initially drove in the sand in auto. I don't remember the temperature, but I didn't allow it to get out of control. Temps leveled out fairly soon to about the same as highway temps after going into manual mode.

 

[heamick]

I use manual mode when towing and especially on downhill grades. You can basically pick your decent speed with the gear.

Also when off road I prefer t ochice the gear rather than having the transmission shift at an undesirable moment.

yes I do and I d it call Haven n g es the way it runs after learning how frond the new shift goes patterns

 

[MadDog27]

I use it when I am wheeling. It helps keep the trans temp down since it locks the torque converter. I run 20 to 30 degrees cooler running in "manual mode" than auto in 4L crawling on the trail

Was searching through this thread and was really looking for this comment. Was out snow wheeling this weekend and my trans temp was going up when I was in the deep stuff. My buddy told me when he wheeled an auto he would use manual mode to keep the temps down.

Im assuming this is true? I have been just using “D” for all my off roading. Guess I need to try using the manual mode to pick my gears and keep temps down. I was also curious why this keeps it down, your comment helps to understand the reasoning behind it.

Edit: Just read that this may not be the case but sounds like in your experience it has lowered temps. I’ll give it a shot next time I’m out and see what happens.

 

[J0E]

Edit: Just read that this may not be the case but sounds like in your experience it has lowered temps. I’ll give it a shot next time I’m out and see what happens.

No way it could lock the torque converter but it can prevent excessive slipping (and heat) by being in too high of a gear.

 

[Coops4284]

Was searching through this thread and was really looking for this comment. Was out snow wheeling this weekend and my trans temp was going up when I was in the deep stuff. My buddy told me when he wheeled an auto he would use manual mode to keep the temps down.

Im assuming this is true? I have been just using “D” for all my off roading. Guess I need to try using the manual mode to pick my gears and keep temps down. I was also curious why this keeps it down, your comment helps to understand the reasoning behind it.

Edit: Just read that this may not be the case but sounds like in your experience it has lowered temps. I’ll give it a shot next time I’m out and see what happens.

After talking to my friend who knows way more about this than me, it doesnt "lock" the torque converter. What it does is it stops the torque converter from spinning so much since it is not hunting for a gear, because you have it "manually" locked to a specific gear. Since it is not searching so much it does not generate heat.

 

[jeepoch]

Generally at low speeds (or acceleration/deceleration) the torque converter should not be 'locked'. This is where the most torque is generally produced. As the vehicle's velocity increases and becomes more constant, where the input shaft (from the engine) and output shaft (to the transmission) speeds become equal, is the point where the lock-up clutch would normally (and dynamically) be engaged.

In practice this lock-up condition should only practically occur at vehicle speeds where the highest transmission gears are engaged. However, with the sophistication of current modern transmissions with computer controllers this lock-up could be applied at any velocity where the above conditions apply (equal input and output shaft speeds).

The primary purpose of this lock is to mechanically connect the motor to the transmission very similar to a manual trans. When the converter is locked, the fluid torque generating process is then bypassed. All power is now mechanically transfered instead of via the fluid. The biggest outcome of this is efficiency. When locked, the fluid dynamics within the torque converter is reduced dramatically. Thus decreasing excessive heat generated by any turbulent flow.

Again this locking is a function of the transmission controller but always dependent on the input and output shaft speeds being near equal. Therefore the selected gear really has no direct influence on this locking mechanism, rather only the constant rotational speeds between the motor and the wheels (through all the applicable gear ratios of the transfer case and axles).

Selecting a gear 'manually' via AutoStick gives you much greater control in minimizing any automatic gear hunting, thus also reducing excessive heat, but the mechanical locking can only occur at constant velocities independent of whichever gear has been selected (either manually or automatically).

So in order to minimize any transmission generated heat, select an appropriate gear for any desired velocity and then maintain that particular speed for as much as possible.

One last note, running at a constant vehicle velocity minimizes fluid turbulence in general, regardless of whether or not the transmission controller locks the torque converter. So throttle control is always the ultimate control point.

Hope this helps.
Jay

 

[PBosch]

I think the manual mode setup of pulling back to shift up is not right. This is not a race car (at least mine isn't), but it is a mopar. Not sure how the current day challengers/chargers have it setup (I'll assume they are backwards), but the old school mopars like my 74 charger with the 440 and a slapstick automatic its pull back to shift down, pop it forward to go up. Same thing with my newer Toyota product. I guess in the end it seems like a simple software setting could be made available for people to select the shift direction. I've peen pulling back to shift down for over 40 years now and I CONSTANTLY get it backwards on the JL, to the point I just don't use it except on super rare occasions.

 

[JLUS]

I think the manual mode setup of pulling back to shift up is not right. This is not a race car (at least mine isn't), but it is a mopar. Not sure how the current day challengers/chargers have it setup (I'll assume they are backwards), but the old school mopars like my 74 charger with the 440 and a slapstick automatic its pull back to shift down, pop it forward to go up. Same thing with my newer Toyota product. I guess in the end it seems like a simple software setting could be made available for people to select the shift direction. I've peen pulling back to shift down for over 40 years now and I CONSTANTLY get it backwards on the JL, to the point I just don't use it except on super rare occasions.

I can confirm my challenger and my JL are both down to go up in gear as expected for Mopar.

 

[heamick]

I've owned my Jeep since July and literally just noticed this option last week. I don't recall seeing it mentioned in the manual (yes, I'm a nerd and read the whole thing), but might have glossed over it.

Is there any real benefits to using this, or is it just to feel more sporty? Any dangers with it, or ways that I could mis-use it accidentally and cause damage?

all the time, I downshift it m=myself and up shift

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