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SRT8 W5A580 Trans Question

5K views 13 replies 5 participants last post by  soontobesrt 
#1 ·
Anyone know if the programming has been updated for this trans in SRT8 that allows for RPM matched downshifts since it has paddle shifters on the steering wheel? That would be sweet!
 
#3 ·
Very good question! I know that the older A580s did not have the feature as downshifts weren't seamless and actually allowed for engine breaking. The downshift rev matching I believe HAS BEEN introduced on the new transmission tuning but dont quote me.

Don't remember where I read it, probably Milous info or WK2 jeeps maybe but one of the modes sport/track had this feature I think as they control the trans/suspension/engine tuning and it allowed for rev matching for ideal use of the paddles :) Hope Im recollecting correctly, maybe someone knows for sure?
 
#4 ·
Wouldn't it have to be ? Otherwise wouldn't it just be moving the old shifting from the console up to the paddles? So that is not much of an imporvment in my mind.

True paddle shifting matches revs...
 
#5 · (Edited)
Well, the AMG folks might beg to differ, none of theirs do it and they use the same trans. Personally, I'm of the belief anything short of a dual clutch or sequential auto-manual isn't "paddle shift" but merely an extension of the slap stick shifting on a slushbox that goes by a number of different names.
 
#8 ·
^^^^

The WV DSG, Porsche PDK both rev match on downshift via fly by wire and I'm sure others like the BMW and Ferrari systems do as well. My wife's SE5 Can-Am Spyder rev matches or "blips" the throttle on downshifts via a hard cabled servo setup.
 
#9 · (Edited)
hmmm, have any information on these systems? Im googling as I type as I may edit this once I stumble upon it. Seems to make sense based on what you are saying. Im guessing the TCM communicates with the TPS system and automatically blips the throttle the appropriate calculated amount based on the rev change.

The only thing Im still wondering about is the physical transmission action. For a true rev match like in a MT,the trans has to be effectively disengaged, throttle blipped, then reengaged in the lower gear. So guessing for a rev match the computer obviously does it all when the paddle shift down is signaled. Guess its not too much to design into the system, I just dont know exaclty how they do it and what it takes. Seems simple enough, I just figured its not something youd normally see in a Jeep nut then again WHO THE HECK thought they'd ever see FLAPPY PADDLES in a JEEP :eek: Im not against it :)


EDIT: Interesting reads on some newer cars and other forums talking about similar stuff. Apparently the 370Z claims it has this but I too wonder exactly how it does it?

http://www.bimmerfest.com/forums/archive/index.php/t-510059.html
http://www.the370z.com/nissan-370z-...synchrorev-match-vs-non-synchrorev-match.html
 
#10 ·
On our GTI with the DSG the electronic throttle increases the revs when the trans shifts to a lower gear but because it's a dual clutch there is no neutral or a time when the clutch is disengaged since it engages the second clutch AS it's disengaging the first. I've noticed that if you paddle shift down and aren't slowing down it will rev match to the lower gear but if you don't also push down the throttle it will engine brake as it comes back to your commanded throttle position. When the throttle position is zero and you downshift it rev matches then removes the throttle so engine braking is more abrupt but not as abrupt as dropping the clutch on a manual without adding throttle. From what I've read it's a much about reducing shock loads to the trans as it is about performance.

On a slushbox with a torque converter there's so much going on based on hydraulic pressures that aren't controlled by the ECU that it would make it next to impossible to program the e-throttle to correctly compensate. I imagine it could be done but I suspect there's so little payback that it's not worth the effort.
 
#11 · (Edited)
Exactly, yea Im with you. So from this the chances that "revmatching" has been built intot his trans programing is slim to none and i think well . . . you know how it goes :lol:

Would have been sweet and may have significantly aided in tranny life but at the same time as has mentioned time and time again, this 580 NAG is a proven performer and handle tons of power, more than anything any SRT8 has thrown at it yet :) Im happy with it and think its a god fit for the new Jeep. Id personally hate an 8 speed (not suggesting anything of course) as Id feel like im in an 18 wheeler with all the gear changes and such close ratios ughhh would suck around town, although it would probably pull like a mofo at any and every speed :D I think a nice 6 speed ZF would be the bees knees though a 5 speed with OD for some nice highway mileage :)
 
#13 · (Edited)
If you want to talk trick, a dual clutch executed the way Porsche did with the 500hp turbo would be beyond sweet.

cool link about 6 speed from x3's/3 series - impressive stats, maybe with some srt tuning this could be the new trans haha
http://www.topspeed.com/cars/car-ne...lows-by-nissan-gt-r-in-drag-race-ar90261.html
OH YESS! Very nice, love the PDK's and anything dual clutch is certainly going to be better as long as its executed propel. I mean just the idea of being able to have a separate clutch is appealing as far as time and power delay goes :) I really like the older SMGs in the BMW and have only heard good things about the new DCT they have. The 135i shifted awesome when I test drove it, very fast and put me back into my seat through third gear easily!

*cool link below on trans used in some x3/3 series. Maybe with some srt tuning it would make a nice 6 speed auto for the SRT? Has some nice #s to support

http://www.oneseriesbmw.com/forums/...f-6-speed-automatic-transmission-details.html

Realistically the cost associated with that kind of trans technology isn't something I can see being thrown into the Jeep just due to the market and their target MSRP's but I really cant say it wont happen either. Maybe the '13 will get a new ZF 7DT like that of the PDK in the Porsches. To me any new dual clutch trans with a rev matching feature programmed into the sports system is a win :eek:

Im all for any performance improvement of that stature if they keep the sticker under $50k! . . . give or take a few thousand I guess :rolleyes:
 
#14 · (Edited)
Well just to note, it has been confirmed in car and driver article it doesn't rev match as expected :(

But as far as I understand, at least w/ the nag trans in the srt8 for now, there is no way to have it really revmatch without changing all tcm/pcm tuning and some other things :( Only because in an auto the transmission is never really disengaged from the motor and during a downshift in an auto the tcm would have to somehow signal the valvebody and stop the hydraulic operation for a brief moment so that the converter fluid pumped into the VB doesn't signal the system to change gears immediately. THEN the pcm would have to signal the throttle control module to blip the throttle to increase the revs the calculated difference for that gear and THEN the hydraulic operation would have to reengage the next lower planetary set immediately. With this all said, I dont know how feasible it would be to make this all happen and the costs of it. So is it possible? YES. Is it likely to happen ever for the WA580, NO.

Maybe w/ the new 8-speed (if they can make it work w/ the 6.4) itll be incorporated, I mean enough demand and enough hype building to get the word to them, and maybe they will make it happen.

I think they have bigger issues though w/ this high (for a Jeep) price-tag. In my mind its still a deal as they given us A LOT more for our $ with this new one it seems. Sure its a Jeep but were trying to move up in th car world and price will and has to reflect that if you want true quality materials. Im not against it, Id love to see Jeep climb up to the BMW/Range with one of their models.
 
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