JL Transmission shifting

[sherpaJL]

Anyone know what triggers the automatics to shift.
I imagine it to be a series of sensors feeding back to the PCM / TCM.
Wheel speed, load on the engine, rpms, etc ??

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[grimmjeeper]

It's all computer control. And it's coordinatd with engine data. Throttle position, engine load (air flow), engine speed, transmission input speed, transmission output speed (or wheel speed), and a bunch more.

 

[Obi Wan]

What Grimm said exactly.

More interestingly, why the question? What's cooking up in that mind of yours?

 

[AFD]

I could be wrong, but it seems to also take into account your incline angle (if any) by downshifting when coasting down a steep hill. Probably the same going up hills, though this seems less aggressive and imo, tries to stay in the higher gears for far too long.

 

[Heimkehr]

I could be wrong, but it seems to also take into account your incline angle (if any) by downshifting when coasting down a steep hill. Probably the same going up hills, though this seems less aggressive and imo, tries to stay in the higher gears for far too long.

The 850RE is a computer-controlled adaptive transmission. That is to say, the shift points will adjust over time based on monitored user inputs. That was exactly my experience, which I knew to expect when I took delivery of my new JLU. Said differently, the ZF knows if you have a light or a heavy right foot, and adapts accordingly.

 

[grimmjeeper]

I could be wrong, but it seems to also take into account your incline angle (if any) by downshifting when coasting down a steep hill. Probably the same going up hills, though this seems less aggressive and imo, tries to stay in the higher gears for far too long.

That's based on throttle position most likely. Take your foot off the gas and apply the brake and it will stay in gear to hold speed until you hit the gas. It may also let off and up shift if it can't hold speed.

 

[Tool Guy]

The 850RE is a computer-controlled adaptive transmission. That is to say, the shift points will adjust over time based on monitored user inputs. That was exactly my experience, which I knew to expect when I took delivery of my new JLU. Said differently, the ZF knows if you have a light or a heavy right foot, and adapts accordingly.

And it's an outstanding transmission. I have it (or a variant of it) in the JLUR, a BMW Z4 M40i and a BMW X3 M40i. It performs amazingly in all three. Now compare that to the POS 6 speed auto trans in my Tacoma and that's whole different discussion.

 

[Heimkehr]

And it's an outstanding transmission. I have it (or a variant of it) in the JL, BMW Z4 M40i and a BMW X3 M40i. It performs amazingly in all three.

I wanted the third pedal in my Jeep. There just wasn't a love connection during the test drive process, though, so I selected the 8-speed. I can't say enough good things about the 850RE. It's superlative.

 

[AFD]

That's based on throttle position most likely. Take your foot off the gas and apply the brake and it will stay in gear to hold speed until you hit the gas. It may also let off and up shift if it can't hold speed.

Could be, but I've tried it different ways on my commute. Flat to steep hill descent without applying any brake or gas still quickly downshifts and slows on its own. Same grade transition with just a very light brake tap just gives a sooner downshift. If applying very light throttle instead, it seems to maintain gear and momentum downhill. I also have the eTorque, so maybe the belt-drive regeneration is coming into play?

No idea, but my JL definitely has an incline sensor that's displayed on the dash, so figured it wasn't completely out of the realm of possibility for the transmission to also make use of that sensor. Whatever it's doing sure as heck feels like intentional engine braking when going downhill. And when going up hill, I always have to really get into the throttle to maintain speed and encourage a downshift, when a manual downshift with less throttle would've been adequate ?

 

[Reinen]

I could be wrong, but it seems to also take into account your incline angle (if any) by downshifting when coasting down a steep hill. Probably the same going up hills, though this seems less aggressive and imo, tries to stay in the higher gears for far too long.

I go up and down long steep hills all the time.

If you don't hit the gas going down (or brake) it will hold lower gears to reduce speed increase. It will become more aggressive about it if you often switch to manual and force it to hold a lower gear.

Going up, it all depends on your accelerator input. If you're light on the gas it will hold higher gears longer. If you routinely give heavier "corrections" on the pedal it will learn to hold lower gears longer.

 

[Richardrocks]

And it's an outstanding transmission. I have it (or a variant of it) in the JLUR, a BMW Z4 M40i and a BMW X3 M40i. It performs amazingly in all three. Now compare that to the POS 6 speed auto trans in my Tacoma and that's whole different discussion.

My 2018 Tacoma had the worst transmission I’ve ever experienced… it’s like the engine and transmission fought. A TSB helped a little, but it was seriously demoralizing. I have zero complaints about the JL one!

 

[Tool Guy]

I've got a full tune on my 2020 Tacoma and it still sucks. I love my Toyota's but they really dropped the ball on these transmissions.

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