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-   -   8 speed transmission behavior (http://www.jeepgarage.org/f109/8-speed-transmission-behavior-69405.html)

200sxr 12-19-2013 06:34 PM

8 speed transmission behavior
 
Just want to validate the behavior of the transmission in paddle shift mode.

My GC is a export Diesel, here is what I have found;

* In paddle shift mode (and in both Sport mode and ECO mode) the transmission will kick down one gear; eg select a gear using the paddle, say with the engine speed around 1500rpm and if you go WOT the transmission will go down a gear.

* Again in paddle shift mode, the transmission will shift up a gear when it approaches the designed engine speed when a up shift occurs (~3700rpm - 3900rpm). The behavior is the same in either ECO or sport mode.

Is the behavior the same with the non diesel engines?

SNUKE 12-19-2013 09:17 PM

Re: 8 speed transmission behavior
 
Could just be my brain, but I have read that a few times and do not know what you are saying.

What does "WOT" mean?

jbjones85 12-19-2013 09:20 PM

I can't comment on the diesel part but wot is wide open throttle.

SNUKE 12-20-2013 03:16 AM

Re: 8 speed transmission behavior
 
Thanks, it makes sense now.
So up and down shifting by itself when you are supposed to have manual control over it, and rather than hold a gear, it changes it.

Manual suggests it will do this

"In Paddle Shift mode, the transmission will shift up or down when (+/-) is manually selected by the driver, unless an engine lugging or overspeed condition would result. It will remain in the selected gear until another upshift or downshift is chosen, except as described below.
• The transmission will automatically downshift as the vehicle slows (to prevent engine lugging) and will display the current gear."

I have not used the shifters, i will give it a try tomorrow.

200sxr 12-20-2013 05:32 PM

Re: 8 speed transmission behavior
 
Yes WOT is wide open throttle, I guess it is a bit misleading as mechanically there is no real throttle in a diesel engine. Maybe I should just call it "flooring it" :)

What I have found in manual or paddle mode is the transmission will not hang on to the selected gear. It will down shift as I "floor it" and it will also upshift to the next gear as I approach the programmed up shift engine speed.

I understand the exception is as the car slows down or coming to a stop the transmission would shift down to the appropriate gear.

I really would prefer if I have selected a gear in manual mode the transmission would stay in that gear no matter what, just like a good old manual transmission.

bill_de 12-20-2013 05:51 PM

Re: 8 speed transmission behavior
 
Have you tried it in Sport mode?

My last vehicle, non Jeep, would let the paddles over ride normal shift points when in sport, but not in drive.


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loveracing1988 12-20-2013 09:11 PM

Our V6 will stay in whatever gear you command unless it will over rev the engine or lug the engine. If you put it in 8th gear going 40 and floor it it will stay in 8th gear.

SNUKE 12-20-2013 09:31 PM

Re: 8 speed transmission behavior
 
1 Attachment(s)
I took the GC for a quick run up to Bilpin, to play with it through the twisty hill climb.'It changes up like it is in full auto mode.

Here is a video of it doing it in Sport mode. I selected first and it did the rest itself.
I didn't really try the downshift though. The two times i tried it wouldn't do it.

If it wasn't stupid enough to be filming this myself while driving I would have gotten the tacho in shot too.

200sxr 12-21-2013 02:52 AM

Re: 8 speed transmission behavior
 
So it looks like the diesel transmission is programmed differently to the V6. It will not hold gear in paddle / manual mode in ECO, non ECO or sport mode which is a little bit disappointing!

loveracing1988 12-21-2013 07:55 AM

Quote:

Originally Posted by 200sxr (Post 948596)
So it looks like the diesel transmission is programmed differently to the V6. It will not hold gear in paddle / manual mode in ECO, non ECO or sport mode which is a little bit disappointing!

I have read conflicting stories on this. I have read of other people having theirs act just like yours. You are just limiting the top gear the transmission goes into. That makes sense to me because ours acts the same whether you use the paddles in sport mode or normal mode. To me it should act the way yours does in non eco mode and the way ours does in sport mode. If you want to limit your highest gear for towing or something like that all you do is put it in say 6th gear and it will go 1-6 all by itself, but if you want to control what gear it goes in, switch to sport mode and use the paddles and you can do that too.

SNUKE 12-21-2013 08:10 AM

Re: 8 speed transmission behavior
 
But you can't get it to hold the gear selected, it won't hit a rev limiter it just shifts up.
I couldn't get it to drop into second for a tight corner, it would not drop lower than 3rd until it was past the point of use as an engine brake combined with actual brakes.

loveracing1988 12-21-2013 08:17 AM

Quote:

Originally Posted by SNUKE (Post 948643)
But you can't get it to hold the gear selected, it won't hit a rev limiter it just shifts up.
I couldn't get it to drop into second for a tight corner, it would not drop lower than 3rd until it was past the point of use as an engine brake combined with actual brakes.

In that respect the diesel might be differnt since you don't have true engine braking. It might be designed that way to control boost and such. Im thinking if you wanted a vehicle you can hustle around like that a grand cherokee with the diesel might not be your best choice.


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