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Automatic Tranny Questions
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Author:  BoyNamedSue [ Tue Apr 10, 2007 1:12 am ]
Post subject:  Automatic Tranny Questions
I'm new to an automatic and had some questions:

1. When should you use 2 and 1?

2. What should you use going up a steep highway to the top of a mountain to a ski resort?

3. Say you're going up a steep trail which doesn't require 4-LO. I've read that using 4-HIGH can lead to overheating. Should you be using 4-LO even though the extra traction isn't needed, or can you use the 1 or 2 setting combined with 4-HIGH?

4. Why does using 4-HIGH in the above situation lead to overheating? I read an explanation in another thread, but I still don't get it.
Author:  Blue KJ in PA [ Tue Apr 10, 2007 7:25 am ]
Post subject: 
See page 224 of your 2007 KJ owners manual or download it from Jeep.com

2 (Second) for moderate grades and to assist braking on dry pavement or in mud and snow. Begins at a stop in low gear with automatic upshift to 2nd gear. Will not shift to 3rd.

1 (First) For hard pulling at low speeds in mud, sand, snow, or on steep grades. Begins and stays in low gear with no upshift. Provides engine compression braking at low speeds.

Going up a hill leave it in D maybe turn off the OD but let the tranny shift on its own. Downhill do the same unless you are towing.

I'll leave the rest for someone else... :)
Author:  sleeve84028 [ Tue Apr 10, 2007 12:29 pm ]
Post subject:  Re: Automatic Tranny Questions
BoyNamedSue wrote:
1. When should you use 2 and 1?


For daily driving - you'll probably never need to use 1st or second gear.

1st gear has a maximum speed of maybe 25MPH? (I've never actually tried to top it out) and is good for stump pulling or situations where slow speeds and high RPM's are needed

2nd gear - I've never used, unless I accidently put the gear selector in that postion

BoyNamedSue wrote:
2. What should you use going up a steep highway to the top of a mountain to a ski resort?


Depends on the snow / ice situation but I'd say Part Time four wheel drive, OD turned off and the gear selector left in the drive positon
For me, it'd be Full Time 4wd, OD off and in D

BoyNamedSue wrote:
3. Say you're going up a steep trail which doesn't require 4-LO. I've read that using 4-HIGH can lead to overheating. Should you be using 4-LO even though the extra traction isn't needed, or can you use the 1 or 2 setting combined with 4-HIGH?


Slow and steady is better than fast and broken. Or if it's possible move into and out of 4-low when you are getting ready for a very steep climb / steep decent.

BoyNamedSue wrote:
4. Why does using 4-HIGH in the above situation lead to overheating? I read an explanation in another thread, but I still don't get it.


This relates back to Fluid temperatures..

When you are in 4-high and try to do a very long & steep climb you are relying on the engine / transmission alone to provide the power & gearing to give you the forward momentum you want (by pressing the gas pedal). By doing this, the transmission fluid gets hotter and with little to no air flow moving past the transmission cooler or transmission oil pan there is really no way for that heat to be transfered out of the fluid. Thus the hot fluid is recirculated back into the system and it just continues to get hotter and hotter until the fluid turns to water and your transmission becomes a piece of toast.

By using 4-low you take the output of the drivetrain and multiply it by it's mechanical advantage (14 to 1 is it?) and this then reduces the amount of work that the transmission needs to perform on it's own. In turn, reducing the amount of work will automatically reduce the amount of heat generated and this is what saves your transmission.
Author:  BoyNamedSue [ Tue Apr 10, 2007 12:54 pm ]
Post subject: 
Thanks for the info.
It's starting to make sense now.

Is this correct:
1. When in the "1" position it starts and stays in 1st gear, no matter what.
2. When in the "2" position it starts and stays in 2nd gear, no matter what.
3. When you deactivate "overdrive" it starts in 1st gear, goes to 2nd, then 3rd, but never ever goes into 4th.
Author:  tjkj2002 [ Tue Apr 10, 2007 12:59 pm ]
Post subject: 
Quote:
. When in the "2" position it starts and stays in 2nd gear, no matter what
Starts in 1st gear then shifts in 2nd,but not into 3rd or 4th.It will shift back into 1st when needed also,putting it in 2nd just locks out 3rd and 4th.
Author:  sleeve84028 [ Tue Apr 10, 2007 1:04 pm ]
Post subject: 
but everything else is correct (other than what tjkj pointed out)
Author:  BoyNamedSue [ Tue Apr 10, 2007 1:16 pm ]
Post subject: 
I'm glad to be finding out I still have a little control over the gears since I traded in my manual for an automatic.

A couple other questions:
1. Can I switch to "overdrive", "1", "2" while moving or do I need to be stopped? (I'm pretty sure I can switch in and out of overdrive whenever I want to, not sure about "1" and "2").

2. What mode would you use to pull a car out with a tire stuck in a ditch?
Author:  tjkj2002 [ Tue Apr 10, 2007 1:22 pm ]
Post subject: 
BoyNamedSue wrote:
I'm glad to be finding out I still have a little control over the gears since I traded in my manual for an automatic.

A couple other questions:
1. Can I switch to "overdrive", "1", "2" while moving or do I need to be stopped? (I'm pretty sure I can switch in and out of overdrive whenever I want to, not sure about "1" and "2").

2. What mode would you use to pull a car out with a tire stuck in a ditch?
You can shift into 2nd or 1st at there relitive speeds,you should be going no more than say 35-40 mph to go into 2nd and 10-15 mph to go into first.Since our trannies are electronic they won't shift down even when you put the shifter in the lower gear until the vehicle speed is "safe" to shift into anyway.As far as pulling someone out of a ditch I saty in drive with the overdrive locked out,and if needed I'll put in 4-lo.
Author:  BoyNamedSue [ Tue Apr 10, 2007 2:34 pm ]
Post subject:  Re: Automatic Tranny Questions
Quote:
This relates back to Fluid temperatures..

When you are in 4-high and try to do a very long & steep climb you are relying on the engine / transmission alone to provide the power & gearing to give you the forward momentum you want (by pressing the gas pedal). By doing this, the transmission fluid gets hotter and with little to no air flow moving past the transmission cooler or transmission oil pan there is really no way for that heat to be transfered out of the fluid. Thus the hot fluid is recirculated back into the system and it just continues to get hotter and hotter until the fluid turns to water and your transmission becomes a piece of toast.

By using 4-low you take the output of the drivetrain and multiply it by it's mechanical advantage (14 to 1 is it?) and this then reduces the amount of work that the transmission needs to perform on it's own. In turn, reducing the amount of work will automatically reduce the amount of heat generated and this is what saves your transmission.

Ok. One last question for now:
What if you are driving up a very steep paved road where you can not use 4WD because there's too much traction. How do you keep from overheating in that type of situation?
Author:  carroll952 [ Tue Apr 10, 2007 2:43 pm ]
Post subject:  Re: Automatic Tranny Questions
BoyNamedSue wrote:
Quote:
This relates back to Fluid temperatures..

When you are in 4-high and try to do a very long & steep climb you are relying on the engine / transmission alone to provide the power & gearing to give you the forward momentum you want (by pressing the gas pedal). By doing this, the transmission fluid gets hotter and with little to no air flow moving past the transmission cooler or transmission oil pan there is really no way for that heat to be transfered out of the fluid. Thus the hot fluid is recirculated back into the system and it just continues to get hotter and hotter until the fluid turns to water and your transmission becomes a piece of toast.

By using 4-low you take the output of the drivetrain and multiply it by it's mechanical advantage (14 to 1 is it?) and this then reduces the amount of work that the transmission needs to perform on it's own. In turn, reducing the amount of work will automatically reduce the amount of heat generated and this is what saves your transmission.

Ok. One last question for now:
What if you are driving up a very steep paved road where you can not use 4WD because there's too much traction. How do you keep from overheating in that type of situation?


Depending how steep the road is you might have to use 4-Low. It really depends on the incline on the road. There are times where you will use 4-Low in high traction areas (Moab) and things will break. In Hawaii, on the Big Island I think, there are a few paved roads that have signs requiring a vehicle with a 4-low because of the incline.

Hope that helps, some folks may know better. I'd say it's very circumstancial. Most steep paved roads (for example going up to the crest a mountain) should be fine in 2wd.

Edit - Just thought of something, in those cases, you might want to turn off your AC and any big accesories if you're worried about your engine getting hot.

Justin
Author:  sleeve84028 [ Tue Apr 10, 2007 3:32 pm ]
Post subject: 
Yeah, any paved road should be safe in 2WD. Just turn off the OD and head on up... If you get stuck in traffic or the speeds start to drop to a point where there isn't much air moving across the transmission cooler than you might start to "think" about taking a break. But in most cases, driving up and down a paved mountian road will be fine as you should be fine.

I've only visited the state of Hawaii - I wish I could return!

Another trick that aids the engines ability to remove heat: Turn the Heater on full blast and roll down the windows (for fresh air). Since the heater core is basically a mini-radiator; any and all heat that is removed from it will only aid in your quest to keep the engine running cooler. And if your transmission cooler is plumbed through the engine radiator, this can help cool your transmission fluid in extreme situations

In all of my experiences with the Liberty I've never had the transmission light come on and while a few others have - it wasn't anything that a cool down wasn't able to cure.
Author:  BoyNamedSue [ Thu Apr 12, 2007 1:53 am ]
Post subject: 
1. The manual says if going up a steep trail put the gear selector in low or "1" and use 4WD-Low.
Why does it say to put the gear selector in low? If you're going up a steep hill at a slow speed won't the vehicle stay in the lowest gear anyway as long as you don't speed up?

2. And just to clarify, It is recommended to shift into "2" or "1" or in and out of overdrive while moving as long I'm at a safe speed for the gear I'm moving into..........I don't have to be at a stop for any of this?

3. And the final question:
When you shift into 4-Low it says to use neutral gear at 2-3mph. After you make the shift do you move the gear back into Drive or "1" or "2" while moving, or do you have to stop first. My guess is you shift into 4WD-LOW, then while still moving you shift into your chosen Gear and just press the pedal. What would happen if you shift into 4-LOW and stop first?
Author:  sleeve84028 [ Thu Apr 12, 2007 7:44 am ]
Post subject: 
BoyNamedSue wrote:
1. The manual says if going up a steep trail put the gear selector in low or "1" and use 4WD-Low.
Why does it say to put the gear selector in low? If you're going up a steep hill at a slow speed won't the vehicle stay in the lowest gear anyway as long as you don't speed up?


The logic behind this statement in the owners manual is two fold:

1) As you pointed out - the legal team at DCX doesn't want you to have grounds to sue them if you grenade your T-case after driving around at 50 mhp in the 4-low setting. So they stipulate that you should be in the 1st gear setting to avoid overspeeding

2) It gives some people an idea of what the "speed limit" is for the 4-low setting. But as you stated, as long as you are going less than 15mph (and in Drive) the transmission will automatically stay in first gear. I've done it but you have to go SLOW or the transmission will shift gears and depending on what surface you're on that might not be a very happy experience


BoyNamedSue wrote:
2. And just to clarify, It is recommended to shift into "2" or "1" or in and out of overdrive while moving as long I'm at a safe speed for the gear I'm moving into..........I don't have to be at a stop for any of this?


Correct - the clutches are all automatic so you only tell the car what gear you want

BoyNamedSue wrote:
3. And the final question:
When you shift into 4-Low it says to use neutral gear at 2-3mph. After you make the shift do you move the gear back into Drive or "1" or "2" while moving, or do you have to stop first. My guess is you shift into 4WD-LOW, then while still moving you shift into your chosen Gear and just press the pedal. What would happen if you shift into 4-LOW and stop first?


No stopping involved...

PRNDL goes to N
T-case lever goes to N
(coast down to 2 or 3mph)
Pull T-case lever to 4-low setting (some grinding might occur or lever might be hard to pull)
PRNDL goes to desired gear
continue along the trail


If you select 4-low and then stop, I don't think anything bad will happen as you've already selected the correct transfercase postion. Thus the transmission is in Netural. Selecting the proper gear from a stand still would be safe... But just remember you need to be moving in a forward direction while selecting the 4-low postion.
Author:  BoyNamedSue [ Fri Apr 13, 2007 11:39 am ]
Post subject: 
Hope I don't drive anyone crazy with all my questions, but I have a couple more. I just like to learn all of this stuff. It's amazing how clueless the people I know with automatics are. They think "overdrive" is something that makes you go faster like some kind of turbo setting, and they have no clue what the "1" and "2" gear settings are for. Plus nobody changes their transmission fluid and they seem proud of it.

1. If the transmission is electronic does that mean the gear selector lever doesn't really move anything. Is it just the equivalent of pressing a button? For example if you had the same P,R,D,1,2 on some buttons on the console would this accomplish the exact same thing?

2. How come the manual recommends putting the Jeep in "neutral" when sitting for a long time, or when overheating? Why is "neutral" better than "park" in those situations?
Author:  dirtykj [ Fri Apr 13, 2007 11:45 am ]
Post subject: 
Blue KJ in PA wrote:
1 (First) For hard pulling at low speeds in mud, sand, snow, or on steep grades. Begins and stays in low gear with no upshift. Provides engine compression braking at low speeds.


They lie :evil: There's no engine compression to speak of in my '05 ... it's horrible.
Author:  dirtykj [ Fri Apr 13, 2007 11:49 am ]
Post subject:  Re: Automatic Tranny Questions
BoyNamedSue wrote:
What if you are driving up a very steep paved road where you can not use 4WD because there's too much traction. How do you keep from overheating in that type of situation?


2nd. I've only driven on some roads in Big Bear where I felt I needed to lock out 3 and 4.
Author:  FastTRX [ Fri Apr 13, 2007 11:55 am ]
Post subject: 
sleeve84028 wrote:

1) As you pointed out - the legal team at DCX doesn't want you to have grounds to sue them if you grenade your T-case after driving around at 50 mhp in the 4-low setting. So they stipulate that you should be in the 1st gear setting to avoid overspeeding

2) It gives some people an idea of what the "speed limit" is for the 4-low setting. But as you stated, as long as you are going less than 15mph (and in Drive) the transmission will automatically stay in first gear. I've done it but you have to go SLOW or the transmission will shift gears and depending on what surface you're on that might not be a very happy experience


It's always been a habit of mine to leave the tranny in 2nd when using 4-Lo....or 1st when wheeling in 4-Lo. Leaving it in drive is fine, but if you came to a point where you had wheel spin, you could possibly be spinning the wheels over 25mph, and over that speed you have a chance of blowing up the T-case as you said. So I kinda follow the manual just to be safe in certain situations.
Author:  sleeve84028 [ Fri Apr 13, 2007 12:36 pm ]
Post subject: 
BoyNamedSue wrote:
Hope I don't drive anyone crazy with all my questions, but I have a couple more. I just like to learn all of this stuff. It's amazing how clueless the people I know with automatics are. They think "overdrive" is something that makes you go faster like some kind of turbo setting, and they have no clue what the "1" and "2" gear settings are for. Plus nobody changes their transmission fluid and they seem proud of it.


Trust me - there's plenty of these people out there who don't know a whole lot about the questions you are asking so don't feel bad... If knowledge is power than this thread must be very powerful. (pat's self on back)

BoyNamedSue wrote:
1. If the transmission is electronic does that mean the gear selector lever doesn't really move anything. Is it just the equivalent of pressing a button? For example if you had the same P,R,D,1,2 on some buttons on the console would this accomplish the exact same thing?


The PRNDL (Park, Reverse, Neutral, Drive, Low) has 2 seperate cable attached to it so there is still something mechanical happening when you select different gears.

1) The first cable I'll attempt to descirbe is the Shifter/Key interlock cable. This cable prevents the transmission from being shifted out of park when you are not stepping on the brake pedal. It also prevents the key from being removed if you are not in Park or Neutral. The cable attaches at the PRNDL and is then sent up to the ignition switch. An electronic plunger switch is routed to the brake pedal (from the IGN switch)

2) The gear selector cable is next. This one is the cable that runs to your transmission. On the transmission end is typically a pull-style lever that moves a toggle with the programed detents. Those detented postions are then tranfered to a voltage and then from that voltage your tranmission is put in gear.. (phew that is a lot to chew on!)

BoyNamedSue wrote:
2. How come the manual recommends putting the Jeep in "neutral" when sitting for a long time, or when overheating? Why is "neutral" better than "park" in those situations?


I don't have a good answer for this one - but I'll give you my theory. Park is the selection of two opisite gears (typically reverse and 1 forward gear) and quite possibly if they are engaged for too long could become froozen together as all of the transmission fluid drains from the interfacing components.

Also by using neutral - this forces you to use the parking brake. Which, when neglected, can become non-functional over time.

Neutral also unloads the engine from the transmission (not physically but in a sense) to free up the engine to work more effeceintly... The less load on the engine can trasnlate into less heat generated and this will free up the cooling system to remove the exisiting heat from the car.

As an aside: I've never once heard of the liberty overheating... Some have problems with cracked radiators but I've not heard of a case where the liberty overheated under normal use (not including you guys with mudded up electric fans on the trail)

Edit: coding problems on my quotes...
Author:  sleeve84028 [ Fri Apr 13, 2007 12:40 pm ]
Post subject: 
FastTRX wrote:
It's always been a habit of mine to leave the tranny in 2nd when using 4-Lo....or 1st when wheeling in 4-Lo. Leaving it in drive is fine, but if you came to a point where you had wheel spin, you could possibly be spinning the wheels over 25mph, and over that speed you have a chance of blowing up the T-case as you said. So I kinda follow the manual just to be safe in certain situations.


And here you bring up a very good point. Safety is key! While I've never had to replace a busted transfer case (thank my lucky stars) I don't want to offer any advice to someone online that might potentially have something go wrong... So please use the best judgement you have on gear postions.
Author:  FastTRX [ Fri Apr 13, 2007 2:51 pm ]
Post subject: 
sleeve84028 wrote:
FastTRX wrote:
It's always been a habit of mine to leave the tranny in 2nd when using 4-Lo....or 1st when wheeling in 4-Lo. Leaving it in drive is fine, but if you came to a point where you had wheel spin, you could possibly be spinning the wheels over 25mph, and over that speed you have a chance of blowing up the T-case as you said. So I kinda follow the manual just to be safe in certain situations.


And here you bring up a very good point. Safety is key! While I've never had to replace a busted transfer case (thank my lucky stars) I don't want to offer any advice to someone online that might potentially have something go wrong... So please use the best judgement you have on gear postions.

In other words, sleeve84028 doesn't want to be held liable for your actions that could possibly lead to a blown t-case. Ha...I sound like a lawyer now!! :lol:

Safety is key*, don't ever forget it!!
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