Transmission tuning for quicker shifts.

[fumanchu182]

I was talking with a well known tuner who has a twin turbo Challenger. We were discussing techniques for having the trans shift super fast. One item of discussion was dropping minimum spark on shifts to zero or negative values so the shifts happen super fast. Has anyone used this technique? I'm thinking the table to modify these values on would be the minimum spark table but haven't found a table that correlates to spark as a shift occurs. Would anyone happen to know what table that might be?

 

[16GoManGoHC2]

For a auto or manual? This would be interesting for both!!

 

[fumanchu182]

This is primarily focused on the A8. The speed of the shift is determined by the individual between the clutch and the shifter for M6s.

 

[16GoManGoHC2]

This is primarily focused on the A8. The speed of the shift is determined by the individual between the clutch and the shifter for M6s.

True, but not in my case, I can shift my G5 Trans based Capri lighting fast, to the point of being accused at the track of running a auto (clutch automatic setup if you’ve ever heard of such) in the stick class. This boy can shift trust me. Getting the trans unloaded from the engine and dropping in RPMS quick helps quicker shifting on a stick, it’s how a no lift shift helps. When I time my shifts just right as to hit the rev limiter just after the shift starts, so the rev limiter kills fuel at the same time I’m starting the shift the shift is as butter smooth and quick as if the car was sitting still with the engine off. Having negative timing helps us stick guys too but doing it by boost reference or aircharge isn’t quick enough. It’s why the curiousness in what your trying to accomplish.

 

[Speedy!]

The table you want is Spark Minimum Torque Reduction I believe. I have mine set slightly negative in the very upper RPM and Aircharge area. That was more to protect the trans than help shifts though.

Logs show sometimes it kicks in and sometimes it doesn't so there's something else that also influences it. Logging "Trans Engine Torque Request" will show what's occurring at shift. For example I'll see it on the 1-2 and 2-3 but not 3-4 then again on 4-5. May have to do with how much torque is being requested, dunno, but I'd imagine the shifts are faster when it doesn't kick in but again I wanna protect the trans.

 

[jonx96]

Lots more things I think would actually increase shift speed. As speedy said timing is usually pulled for safety.
Slip time - Ramp time - Fill time combined with shift pressures are all things that will do what you are looking for. The Hellcat is already pretty aggressive on most of these. I have made adjustments to get quicker firmer shifts. But to quick and your trans will not live very long. All of these were stock for me (besides pressures) until right before winter and I only had 2 test pulls playing with these settings and think I found a happy safe place. The first revision just felt to aggressive and I felt the trans would not last like that.
There is less info out there on the trans for these cars than the engine portion. These settings you should proceed with caution.

 

[vortecd]

@Hpindy may have some insight on shifting

 

[Hpindy]

@Hpindy may have some insight on shifting

I'm working on my transmission tuning over the winter so I have no testing yet .. But the transmission tuning definitely holds some time in it ... I'm working with a hydraulic engineer ( there is that word again lol) on the fundamentals of this type of system ... I will definitely share some stuff once I have tested it ...

Sent from my Armor 8 Pro using Tapatalk

 

[fumanchu182]

Lots more things I think would actually increase shift speed. As speedy said timing is usually pulled for safety.
Slip time - Ramp time - Fill time combined with shift pressures are all things that will do what you are looking for…
There is less info out there on the trans for these cars than the engine portion. These settings you should proceed with caution.

I have finally hit these tables and agree. Hellcats from the factory are pretty aggressive. The books recommend not going below certain values but then I see what they say for “aggressive” and Im like yeah… ill be towing it home with values like that…

 

[Speedy!]

Examples from the books?

 

[jonx96]

I have finally hit these tables and agree. Hellcats from the factory are pretty aggressive. The books recommend not going below certain values but then I see what they say for “aggressive” and Im like yeah… ill be towing it home with values like that…

What's the problem there you have a trailer

Examples from the books?

These are the tables he is referring to. None of my changes to these tables are very much but you can feel a difference from minor changes. When we are talking about every 10th possible everything helps.

 

[Speedy!]

I'm asking what settings the book recommends and what are considered aggressive.

 

[fumanchu182]

What's the problem there you have a trailer

These are the tables he is referring to. None of my changes to these tables are very much but you can feel a difference from minor changes. When we are talking about every 10th possible everything helps.
View attachment 68729

Hey hey, I borrowed that trailer to just go to VMP, but am actively looking for a rollback or easy loader. In regards to the time to remove from the fill values, -50, -75 and -100 are way to agressive in the perf/sport/max tables. I was thinking -25ms to start off with in those tables. Thoughts @jonx96 ?

 

[fumanchu182]

@Speedy! the books use -50/-75/-100 ms increments for mild/moderate/aggressive respectively. Issue is for some tables you dont want to go below 50ms or 20ms in certain tables based on the guidance. Even with mild changes you’d have to bring those values right back up to the minimum.

 

[Jack_Toepfer]

For those of you that experienced quicker shifts, how much quicker? I imagine you can see it in the logs.

 

[jonx96]

Hey hey, I borrowed that trailer to just go to VMP, but am actively looking for a rollback or easy loader. In regards to the time to remove from the fill values, -50, -75 and -100 are way to agressive in the perf/sport/max tables. I was thinking -25ms to start off with in those tables. Thoughts @jonx96 ?

I’ll have to take a look when I get back to my laptop. I didn’t just subtract 25 across the board. I will post what I did Shortly. I don’t think I went as aggressive as 25 in track or sport.
i ended up getting stuck in a 6 hour meeting today about Network routes and now my brain is fryed for a few minutes here

 

[vortecd]

I’ll have to take a look when I get back to my laptop. I didn’t just subtract 25 across the board. I will post what I did Shortly. I don’t think I went as aggressive as 25 in track or sport.
i ended up getting stuck in a 6 hour meeting today about Network routes and now my brain is fryed for a few minutes here

His work wanted him to "work" today

 

[fumanchu182]

I’ll have to take a look when I get back to my laptop. I didn’t just subtract 25 across the board. I will post what I did Shortly. I don’t think I went as aggressive as 25 in track or sport.
i ended up getting stuck in a 6 hour meeting today about Network routes and now my brain is fryed for a few minutes here

Same here, after that post I went even lower, I only went for -10 and not in all spots. Just to smooth some things over. @Jack_Toepfer this Friday I'll be testing WOT but I had an incomplete trans tune at VMP, I was afraid to touch the "fill" tables at all as well as touch some of the TCC lockup and especially the torque management tables. So all I did was up line pressure and raise shift points. This will get you somewhat far but as you command more and more pressure and want higher RPM shifts you HAVE to change those tables. They all work in unison. For me I moderately removed how much spark would be removed from the shifts, changed some fill times and even just those the car feels completely different. Here is a graph from a log 4/17 before the changes.


3-4 shift was flaring, torque management was also being a pita, see those sloppy U peaks, keep in mind this was just me going to approximately 30mph, nice and soft around town. Here is a log of me today with all the changes in unison.



Torque managemnet was in and out, peaks are nice and razor sharp, still going ot approxmiately ~30mph cruising around town.

 

[Speedy!]

What's the yellow line in the graph?

On mine so far all I've messed with is the shift pressures and slight changes to slip time. From memory I used a 2018 Demon and 2019 RE as a model using the more performance oriented value from each and adjusted some of the slip times from there but it's been a while since I worked on the trans. I didn't mess with the fill times.

 

[fumanchu182]

What's the yellow line in the graph?

On mine so far all I've messed with is the shift pressures and slight changes to slip time. From memory I used a 2018 Demon and 2019 RE as a model using the more performance oriented value from each and adjusted some of the slip times from there but it's been a while since I worked on the trans. I didn't mess with the fill times.

Yellow is expected torque, orange is actual torque.