'Newb' question about 8 Speed Shifting...

[Maverickxeo]

Just wondering - what is the 'actual' procedure for shifting manually? I *thought* I read in the manual to let off the throttle completely, shift gears, and then get back on the throttle (similar to an actual manual). Is that correct, or can I just 'shift' without letting off throttle? Also, will it automatically shift up at a certain RPM (even in manual mode), or will it actually go to redline and hit the rev limiter?

Sponsored

 

[dchemphill1]

I use it mostly for slowing to save brakes, but have shifted through gears after stop. I usually ease off gas during a shift. Really use the manual mode when in 4lo. Can't help on redline question.

 

[jludave]

Also, will it automatically shift up at a certain RPM (even in manual mode), or will it actually go to redline and hit the rev limiter?

In manual mode it will hold whatever gear you are in.

 

[garyji]

. . . except, that if you come to a stop in 2nd, it will shift to 1st. Not sure about the redline thing. I use mine all the time in the Western NC mountain roads, and just use it like a manual. Never really thought about it, but I think you could shift without "letting-up" but not so sure that's a great idea.
I also use mine to save brakes, and have been doing that for years with no issues.

G.

also . . . if you try to downshift beyond the RPM range, it knows not to do the shift.

G.

 

[Initial-Jeep]

Oh, no, don't let off the throttle completely when shifting an automatic; that'd be dangerous and would be rough on the drivetrain (and possibly your neck).

Manual/Standard transmissions have a clutch that disconnects the transmission from the engine--that's why we let off the gas when engaging the clutch; otherwise, the engine would rev up quickly, having its load suddenly removed with throttle still applied. cf. power shifting

Regular automatics (not the dual-clutch transmissions--a completely different animal) such as ours have a fluidic connection via the torque converter. Since the engine and transmission are always connected, completely letting up on the throttle will completely reverse the momentum in the entire drivetrain and suddenly decelerate the vehicle. Up-shifting at this time (where downshifting would be what's called for, depending on how much the vehicle decelerated) would exacerbate the stress within the transmission and the (lack of) responsiveness of the vehicle.

If your concern is smoothness and being easy on the drivetrain, just up-shift with a moderate-to-low load on the drivetrain, pretty much as it does on its own, not in manual mode.

If your concern is performance, you wouldn't want to let up on the accelerator anyway and that is perfectly fine.

Definitely read the manual. pp. 162-163 explains Autostick:

 

[jeepoch]

@Maverickxeo,

Modern automatic tranny's all have a dedicated Transmission Control Module (TCM). The AutoStick (manual mode) feature is primarily a function of software.

It works by using the shifter or paddles to 'request" either an up or down shift from it's current gear overriding the computer (automatic) control. However, this manual shift is still just a request.

The TCM continues to monitor for any and all transmission fault conditions. It WILL step in and temporarily shift into an appropriate gear (automatically) to prevent any potential damage, to either itself or the engine, such as redlining (if it can).

It will however try to 'honor' your requested gear as best as it can. And overall, it is pretty good at honoring your manual selection.

Also, as per the post above by @Initial-Jeep, the torque converter is always still in-play. Do you ever let off the throttle in full automatic? Can you anticipate when the TCM is going to shift and compensate with the throttle? Of course not.

AutoStick mode is no different. In fact with a well implemented TCM and Engine Control Module (ECM), these two controllers perform a very finely coordinated ballet. They dance an intricate choreography over the internal CAN bus with lots of electronic information exchanged while performing the art of shifting. The throttle can be altered by the TCM, thus overriding the value from the accelerator pedal.

Recall here that the JL, as with almost all modern vehicles, no longer have a mechanical throttle linkage. The accelerator pedal is nothing more than a sophisticated potentiometer which simply inputs a requested throttle position to the ECM. The ECM however is the ultimate authority on where it chooses to get it's throttle data from. When shifting (of any type), the TCM can alter this digital throttle information.

When in AutoStick when you manually shift, the TCM receives your request and will do all of the same things it would normally do just as if the computer decided to do it. This digital CAN dance unfolds without any regard to where the gear selection request came from. Even better, all this happens in typically a few hundreds of milliseconds.

Try that with your left foot on the clutch!

So no, there is absolutely no need to perform any throttle management. This intricate digital dance is all accomplished without any intervention required on your part. It will just auto-magically happen.

Lastly as a side-note, I've personally adjusted my Cluster's EVIC settings (via the setup page) to show the current gear. When I'm in Drive the display will show me Dn where n = [1-8]. Or just n when in AutoStick (manual). In this way I always have a reference to the currently active gear. Recall unlike a manual trans where you can select any gear at any time, AutoStick allows only an upshift or downshift. So knowing what gear your starting from when shifting it over to 'M' is beneficial, especially while off-road in 4Lo.

Hope this helps.
Jay

 

[hiimmike]

Only one way to know about the redline.... put it in first, floor it for 10 minutes and see if your engine blows up! I have no idea but I think initially it will just bounce off the redline and you'll potentially do damage and overheat and once it starts to overheat, the Jeep will give you the finger, call you an idiot and turn off the autostick feature. All speculation.

 

[blnewt]

Give your hill decent control some work when you get a chance when running 4Lo too, it's a useful feature, at least I've found it useful And when using it on trials that you may want it beware, there are some interesting noises as it functions

 

[Maverickxeo]

Give your hill decent control some work when you get a chance when running 4Lo too, it's a useful feature, at least I've found it useful And when using it on trials that you may want it beware, there are some interesting noises as it functions

I don't know if I have hill descent - I have 'selec-speed' which I did have to try out (and I was worried it was broken due to the noises it was making; so I'm familiar haha!)

 

[DavidArmen]

It absolutely goes to redline but I am unsure if it hold it or for how long. I can say though that the 392 definitely holds it for at least a few seconds; I floored one in manual mode and it was holding it at redline with the classic redline oscillation but I didn’t wanna take it any farther and I upshifted after a few seconds.

 

[Jeeps2Little]

I don't know if I have hill descent - I have 'selec-speed' which I did have to try out (and I was worried it was broken due to the noises it was making; so I'm familiar haha!)

I also have a sport s and it has the hill descent feature. Only works in 4lo and it is activated by a dedicated button on the dash and then you bump the +/- on the shifter to raise and lower your desired speed. It does make some funky noises but works incredibly well. Used it for the first time last weekend on a long rocky descent and was pleasantly surprised.

Sponsored