ZF8 shift pressures and timing - for Steven@HP

[ic3man5]

I haven't messed with the clutch pressures on mine, only the line pressure.

The base line pressure for each gear under general? What results are you seeing there?

I bypassed that because on the 6L80 that was more of just what is available and didn't do anything unless the line pressure was lower than the requested pressure for the clutches.

[Speedy!]

Sorry, was doing it from memory and I used the wrong term (I corrected my post).

I've not adjusted any of the ramp settings, only the on coming clutch pressures on the Upshift tab and I only increased the last 2 or 3 rows. This basically firms up shifts at WOT.

[ic3man5]

Sorry, was doing it from memory and I used the wrong term (I corrected my post).

I've not adjusted any of the ramp settings, only the on coming clutch pressures on the Upshift tab and I only increased the last 2 or 3 rows. This basically firms up shifts at WOT.

Okay cool, how much higher have you gone? I've gone double stock so far and it seems to not care much - this is with messing with the ramps also though. I think I'm going to revert everything to stock, increase all the oncoming pressures by 25% and decrease the ramps by 25% and see how that works out.

[Speedy!]

You can use a Demon calibration as a guide. Just be careful with the trans stuff, you can hurt them pretty easy if you get the settings wrong.

[ic3man5]

You can use a Demon calibration as a guide. Just be careful with the trans stuff, you can hurt them pretty easy if you get the settings wrong.

I looked at a 2018 demon file I found on the forums and now I just have more wants. Demon seems to have lower pressures compared to the RAM which makes sense. I've tuned the 6L80 wrong before, I for sure know what wrong feels like; I've applied so much pressure before I thought I was going to snap the driveshaft in half, lol. This ZF seems like its on par or better than the 6L80 when it comes to strength even though its too soon to tell.


I've circled all the values missing on my files. Not sure if this just isn't mapped yet for the RAM or it isn't available on the 2019+. I guess if I don't hear anything from HP tuners here soon I'll submit another support ticket.
missing_parameters.JPG

[DAVECS2]

I have taken this approach when remapping the 850RE on the Gladiator. The issue I currently have is if I drop the airflow anymore in order to engage 8th gear at cruise, 70-85, I cannot set the torque in the pedal demand tables to something that will generate enough power to hold cruise in 8th and 9th reliably.

I would really appreciate the ability to bump up the entrance torque by gear an not set of the torque request to high DTC. The max limit on the Gladiator seems to be 406. When I set 8th gear normal to 506 the transmission slides right into 8th like factory, but ahortly after the fault trips and I am stuck in 8th until I key cycle.

The ability to manage the max torque by gear and eliminate that fault got ng off would pretty much complete my tune for the supercharged Gladiator.

[ic3man5]

I've had a chance to experiment with stuff more. Take this with a grain of salt as this could be completely incorrect and only based on my experience and tuning so far.

Shift Pressures -> Upshift -> Oncoming Ramp
Shift Timing -> Upshift -> Ramp Time
These two seem to correlate to each other. I'm going to call this the Oncoming Clutch apply rate. I've zeroed out these two tables and its actually the "proper" way I'd go about it for tuning the correct pressure since this seems to mask any issues with correct pressures and timing. If everything is zeroed out you can think of the oncoming clutch pressure as "on" and 0 torque (clutch plates just touching) as off, it is instant and as fast as possible. The ramp smooths out how fast this happens. 50ms and a ramp of 0.5 is a good starting point for initial tuning.

I don't completely understand the math behind these two parameters but it seems to be inverted from what you'd normally think. The lower the ramp rate (bar/s) the less it dampens.

EDIT: 1.0 ramp near the upper torque rows is probably better to start on.

Shift Pressures -> Upshift -> Oncoming Clutch
This is the actual pressure that gets applied to the clutches and is what you feel as the final portion of the shift or the RPM differences from what I can tell. If the ramp is too aggressive it makes this stage really hard to tune. 6 bars is about the max you want to use here. I've gone to 9 bars and at the point where it feels like your going to break internals or driveshafts. 0.6-1.0 bar seems like a decent place to be on lower torque areas and 5-6 is a good spot for firm shifts in the higher torque areas. 2.5-4 seems to be the sweet spot for "smooth" shifts.

Shift Pressures -> Upshift -> Offgoing Clutch
This is just how much pressure is used to hold the current clutch while phasing in the next clutch. When going for aggressive tuning, I always zero this out. My theory is if the shift is fast and firm enough you don't need to hold this and its too hard to tell if you are doing premature wear until its too late.

Shift Pressures -> Upshift -> Fill Offset
I don't have as much experience with these tables but this seems to pre 0 torque condition of both plates slipping. Not enough pressure here and you'll see a flare and too much and you'll have an overlap condition. The ZF8HP75 on the 2019 RAM for example I couldn't figure out for the life of me why the 3-4 shift was "binding" until I lowered these. My advice is if you increase oncoming clutch pressure by say 20% you should lower the fill offset by at least 10%.

EDIT: After more tuning, increasing the oncoming pressure, less ramp, and possibly holding the offgoing clutch longer is a lot easier. The values in the fill offset are extremely sensitive. Changing by 0.01 bar was enough to make it flare 100-200RPM during the shift. 3-4 on my vehicle (2019 RAM) the fill offset on the low end were too low by ~10% and the upper I couldn't change from stock without flare so I increased the ramp (pressure not time) to avoid binding.

EDIT2: After more tuning I realized I was getting owned by adapts. It seems the current settings here are only good until a key cycle. The second ignition cycle the adapts adjust everything and will mess up tuning in this section. The stock tune for example on the 3-4 has a lot of values that are way too low on the low end torque and low RPM. (0.10 bar @ 74 lb-ft / 1702RPM). After driving on the first engine start and having flares, the second start would see the majority of the flare go away, third even more. The farther away from "correct" the more key cycles it takes. The same value I mentioned before took almost x3 more pressure to not flare after an adapt reset. I suspect without an adapt reset any added pressure is too much as the adapts have already adjusted for it and its too dumb to know we modified the tables.

Edit3: This seems more like a preliminary stage of the oncoming clutch pressure. If the fill offset is 1.0 bars and the oncoming shift pressure is set to 2.0 bars and there is a ramp the actual pressure applied seems to be 1.0 to 2.0 bars. the fill offset is the "floor" or base of when the pressure gets applied. I don't believe this should be above the oncoming shift pressure. Consider it fine tuning for the ramp and a way to move the shifts closer together.

Shift Pressures -> Upshift -> Flare Adder
I haven't actually played with this one yet but it seems pretty self explanatory. If the Fill offset isn't high enough these tables say how much pressure needs to be added to make up for the slip.

Shift Timing -> Upshift -> Nominal Slip Time
As far as I can tell this doesn't have any say on how fast the shift actually takes place. This held true for my tuning of the 6L80 (GM) also and I'm going to assume it applies here also. This is more or less the time it takes for the Torque Reduction stage to happen, the shorter this time the faster and less time the engine pulls back torque (timing). If you have a flat spot or hang in the middle of the shift, more than likely this is too long.

Torque Management -> Upshift -> Forced Torque Intervention
I didn't play in this area too much but this seems to be the pre-cursor torque management stage. I played around with this by making it so the all the values would equal 0 engine torque (5500 turbine speed @ 350 ft-lb = -350) would actually cause the transmission to never shift even at WOT because it guaranteed the output shaft speed never hit the right speed to shift. It went into a really fun bounce back and forth of the RPMs but never shifted. If I added power to the engine I would account for it here to protect the transmission.

Torque Management -> Upshift -> Main Torque Intervention
This is basically the same as forced torque intervention but is applied DURING the shift instead. Again if I added power to the engine I would account for it here to protect the transmission. From what I can tell on the RAM 200 ft-lb is roughly what OEM spec'd at as reliable; This is a huge increase from the 6L80 as it usually never seen over 40-70 ft-lb on a shift.

EDIT: WOT drops the torque a little bit lower. Roughly around 130 ft-lb which is what I'd expect.



NEW 5/19/22:

Shift Timing -> Oncoming Inertia Mode Delay
I haven't quite figured this one out but reducing this and keeping this LONGER than the offgoing inertia mode delay seems to help the shift timing. I believe this is when the clutch start to engage.

Shift Timing -> Offgoing Inertia Mode Delay
I haven't quite figured this one out but reducing this and keeping this SHORTER than the ongoing inertia mode delay seems to help the shift timing. I believe this is when the clutch start to disengage.

Shift Timing -> Fill Time
I've had really strange delays in WOT shifts and randomly in other spots (very obvious in WOT shifts). Reducing this when increasing the shift pressure seems to have helped here. I suspect too long of a fill time causes the transmission to attempt to reduce or "bleed" the pressure before the shift actually happens causing a really long delay that can be felt. 100ms seems okay here across all temperatures so far. I haven't tested in cold weather yet, this will have to come in the winter months.

Shift Pressures -> Downshift -> Oncoming Clutch
Removed: Update later

Shift Pressures -> Downshift -> Offcoming Clutch
Removed: Update later

NEW 8/6/22:

Downshifts: REMOVED, will update later with better information.

I have found that almost all the pressures in the stock tune are way too low. This is the opposite of the 6L80 tuning GM does where the pressures are set high and the adapts bring it down. The ZF8HP75 has the stock pressures low and the adapts increase pressures.

[james1595]

I'm having an issue with my 2019 challenger rt with the 5.7, in where is doesn't want to shift from 1st to 2nd during a wide open pull. I've tried increasing and decreasing torque management and nothing has worked. I've had other look at my tune but they couldn't find anything wrong. Everything I ask what it could be, everyone says the tune, but never how to fix.

[ic3man5]

I'm having an issue with my 2019 challenger rt with the 5.7, in where is doesn't want to shift from 1st to 2nd during a wide open pull. I've tried increasing and decreasing torque management and nothing has worked. I've had other look at my tune but they couldn't find anything wrong. Everything I ask what it could be, everyone says the tune, but never how to fix.

Try lowering the shift point (rpms) and see if that helps. When I raised mine I had really strange issues I wasn't able to correct (I'm sure there was a limiter somewhere else but didn't have time to find it).

[james1595]

I have it shifting at 5600 rpm, and last I was at the track it was shifting at 6700 rpm. not what I want. I have been messing around a little and think I might have found a solution? I've increased line pressure and torque reduction quite a bit and that seems to have helped, but I won't know for sure till I go back to the track

[ic3man5]

I have it shifting at 5600 rpm, and last I was at the track it was shifting at 6700 rpm. not what I want. I have been messing around a little and think I might have found a solution? I've increased line pressure and torque reduction quite a bit and that seems to have helped, but I won't know for sure till I go back to the track

You might not have enough pressure in the upshift oncoming clutch pressure tables depending on how much power you added. There is a Flare Adder table (on the same tab) that adds more pressure the more it slips. I haven't actually played with the flare adder table and I'm not sure if there is a PID that shows it actually in action.

[JoshCP527]

Torque Management -> Upshift -> Forced Torque Intervention
This is a turbine speed delta by engine trq map. After the shift has gone through and tries to apply line pressure at the end. If its botched and still cant make the hand off this is the map that kicks in and pulls trq to get the gear back in line. Its the final trq reduction and a last ditch hope. You see this usually as timing that doesn't come back right after a slip shift. I found out during the early days disabling some or all trq management cant remember but 4-5 slipper was the outcome with that table able to change how much timing at the end was held till the gear came in line.

[JoshCP527]

I'll also add back in the infancy I played with shift time. I lowered it in the low trq areas and got my trans to damn near chirp tires cruising around without changing anything else. I also increased them and got slippy shifts. The thought process after that was the learning the trans does is also effected by it. IE you drag them out it will slow the adaptive pressure hand off. You shorten it the faster it will adaptive hand off. This was a long long time ago. Also before demon and red-eye cals the only bind up I ever had shifting was when I was lowering the line pressure trq axes numbers to bring in more line pressure earlier in the gears. This was with a max of 10bar wot shift first hand full of gears and 4 or 5 bar high trq last few gears on a 2.5 hellcat on e85.

[james1595]

You might not have enough pressure in the upshift oncoming clutch pressure tables depending on how much power you added. There is a Flare Adder table (on the same tab) that adds more pressure the more it slips. I haven't actually played with the flare adder table and I'm not sure if there is a PID that shows it actually in action.

im not sure either, and test and tunes i get 1, maybe 2 passes down the track so its hard to get it tuned right. but as for the flare adder i did increase it slightly just because i dont know how much pressure the trans can take. here is what i have in it right now, and what i went to the track with, maybe you can have some insight

trans tune 4-22.6.hpt
trans tune 4-22.5.hpt

[james1595]

I'll also add back in the infancy I played with shift time. I lowered it in the low trq areas and got my trans to damn near chirp tires cruising around without changing anything else. I also increased them and got slippy shifts. The thought process after that was the learning the trans does is also effected by it. IE you drag them out it will slow the adaptive pressure hand off. You shorten it the faster it will adaptive hand off. This was a long long time ago. Also before demon and red-eye cals the only bind up I ever had shifting was when I was lowering the line pressure trq axes numbers to bring in more line pressure earlier in the gears. This was with a max of 10bar wot shift first hand full of gears and 4 or 5 bar high trq last few gears on a 2.5 hellcat on e85.

Torque Management -> Upshift -> Forced Torque Intervention
This is a turbine speed delta by engine trq map. After the shift has gone through and tries to apply line pressure at the end. If its botched and still cant make the hand off this is the map that kicks in and pulls trq to get the gear back in line. Its the final trq reduction and a last ditch hope. You see this usually as timing that doesn't come back right after a slip shift. I found out during the early days disabling some or all trq management cant remember but 4-5 slipper was the outcome with that table able to change how much timing at the end was held till the gear came in line.

so what would you recommend i do? increase the delta torque intervention and shorten my shift time? and if yes then by how much

[ic3man5]

so what would you recommend i do? increase the delta torque intervention and shorten my shift time? and if yes then by how much

What is actually happening when it doesn't shift from 1st to 2nd? I would correlate shift pressure to shift time more than the torque intervention. If you increase power on the clutches then you will need increased pressure to have the clutches engage at the same time. From what I can tell the ECU will always attempt to apply the torque reduction based on the shift time. I'm not sure what happens when you go past the physical limits of how quick timing can be pulled and pressure being applied to the clutches.

What happens if you manually shift near WOT RPM while only 50-75% throttle? Sometimes when I manually shift above the intended shift point it will bring out bad tuning that is easier to catch.

[ic3man5]

I updated my post above, I managed to finally tune out the damn bump felt near idle on the 3-2 and 2-1 downshifts especially when the idle is increased.

[james1595]

What is actually happening when it doesn't shift from 1st to 2nd? I would correlate shift pressure to shift time more than the torque intervention. If you increase power on the clutches then you will need increased pressure to have the clutches engage at the same time. From what I can tell the ECU will always attempt to apply the torque reduction based on the shift time. I'm not sure what happens when you go past the physical limits of how quick timing can be pulled and pressure being applied to the clutches.

What happens if you manually shift near WOT RPM while only 50-75% throttle? Sometimes when I manually shift above the intended shift point it will bring out bad tuning that is easier to catch.

It just doesnt shift. It goes past the shift and doesnt try to shift. Ive gotten in the right direction now, it shifts, just instead of 5600, its 6700. Not great, but a step. Aslo i havent really tried using the manual shift in higher rpms, but i know at wot it still just shoots past the shift just like in auto

[ezhik89rus]

I've had a chance to experiment with stuff more. Take this with a grain of salt as this could be completely incorrect and only based on my experience and tuning so far.

Shift Pressures -> Upshift -> Oncoming Ramp
Shift Timing -> Upshift -> Ramp Time
These two seem to correlate to each other. I'm going to call this the Oncoming Clutch apply rate. I've zeroed out these two tables and its actually the "proper" way I'd go about it for tuning the correct pressure since this seems to mask any issues with correct pressures and timing. If everything is zeroed out you can think of the oncoming clutch pressure as "on" and 0 torque (clutch plates just touching) as off, it is instant and as fast as possible. The ramp smooths out how fast this happens. 50ms and a ramp of 0.5 is a good starting point for initial tuning.

I don't completely understand the math behind these two parameters but it seems to be inverted from what you'd normally think. The lower the ramp rate (bar/s) the less it dampens.

EDIT: 1.0 ramp near the upper torque rows is probably better to start on.

Shift Pressures -> Upshift -> Oncoming Clutch
This is the actual pressure that gets applied to the clutches and is what you feel as the final portion of the shift or the RPM differences from what I can tell. If the ramp is too aggressive it makes this stage really hard to tune. 6 bars is about the max you want to use here. I've gone to 9 bars and at the point where it feels like your going to break internals or driveshafts. 0.6-1.0 bar seems like a decent place to be on lower torque areas and 5-6 is a good spot for firm shifts in the higher torque areas. 2.5-4 seems to be the sweet spot for "smooth" shifts.

Shift Pressures -> Upshift -> Offgoing Clutch
This is just how much pressure is used to hold the current clutch while phasing in the next clutch. When going for aggressive tuning, I always zero this out. My theory is if the shift is fast and firm enough you don't need to hold this and its too hard to tell if you are doing premature wear until its too late.

Shift Pressures -> Upshift -> Fill Offset
I don't have as much experience with these tables but this seems to pre 0 torque condition of both plates slipping. Not enough pressure here and you'll see a flare and too much and you'll have an overlap condition. The ZF8HP75 on the 2019 RAM for example I couldn't figure out for the life of me why the 3-4 shift was "binding" until I lowered these. My advice is if you increase oncoming clutch pressure by say 20% you should lower the fill offset by at least 10%.

EDIT: After more tuning, increasing the oncoming pressure, less ramp, and possibly holding the offgoing clutch longer is a lot easier. The values in the fill offset are extremely sensitive. Changing by 0.01 bar was enough to make it flare 100-200RPM during the shift. 3-4 on my vehicle (2019 RAM) the fill offset on the low end were too low by ~10% and the upper I couldn't change from stock without flare so I increased the ramp (pressure not time) to avoid binding.

EDIT2: After more tuning I realized I was getting owned by adapts. It seems the current settings here are only good until a key cycle. The second ignition cycle the adapts adjust everything and will mess up tuning in this section. The stock tune for example on the 3-4 has a lot of values that are way too low on the low end torque and low RPM. (0.10 bar @ 74 lb-ft / 1702RPM). After driving on the first engine start and having flares, the second start would see the majority of the flare go away, third even more. The farther away from "correct" the more key cycles it takes. The same value I mentioned before took almost x3 more pressure to not flare after an adapt reset. I suspect without an adapt reset any added pressure is too much as the adapts have already adjusted for it and its too dumb to know we modified the tables.

Edit3: This seems more like a preliminary stage of the oncoming clutch pressure. If the fill offset is 1.0 bars and the oncoming shift pressure is set to 2.0 bars and there is a ramp the actual pressure applied seems to be 1.0 to 2.0 bars. the fill offset is the "floor" or base of when the pressure gets applied. I don't believe this should be above the oncoming shift pressure. Consider it fine tuning for the ramp and a way to move the shifts closer together.

Shift Pressures -> Upshift -> Flare Adder
I haven't actually played with this one yet but it seems pretty self explanatory. If the Fill offset isn't high enough these tables say how much pressure needs to be added to make up for the slip.

Shift Timing -> Upshift -> Nominal Slip Time
As far as I can tell this doesn't have any say on how fast the shift actually takes place. This held true for my tuning of the 6L80 (GM) also and I'm going to assume it applies here also. This is more or less the time it takes for the Torque Reduction stage to happen, the shorter this time the faster and less time the engine pulls back torque (timing). If you have a flat spot or hang in the middle of the shift, more than likely this is too long.

Torque Management -> Upshift -> Forced Torque Intervention
I didn't play in this area too much but this seems to be the pre-cursor torque management stage. I played around with this by making it so the all the values would equal 0 engine torque (5500 turbine speed @ 350 ft-lb = -350) would actually cause the transmission to never shift even at WOT because it guaranteed the output shaft speed never hit the right speed to shift. It went into a really fun bounce back and forth of the RPMs but never shifted. If I added power to the engine I would account for it here to protect the transmission.

Torque Management -> Upshift -> Main Torque Intervention
This is basically the same as forced torque intervention but is applied DURING the shift instead. Again if I added power to the engine I would account for it here to protect the transmission. From what I can tell on the RAM 200 ft-lb is roughly what OEM spec'd at as reliable; This is a huge increase from the 6L80 as it usually never seen over 40-70 ft-lb on a shift.

EDIT: WOT drops the torque a little bit lower. Roughly around 130 ft-lb which is what I'd expect.



NEW 5/19/22:

Shift Timing -> Oncoming Inertia Mode Delay
I haven't quite figured this one out but reducing this and keeping this LONGER than the offgoing inertia mode delay seems to help the shift timing. I believe this is when the clutch start to engage.

Shift Timing -> Offgoing Inertia Mode Delay
I haven't quite figured this one out but reducing this and keeping this SHORTER than the ongoing inertia mode delay seems to help the shift timing. I believe this is when the clutch start to disengage.

Shift Timing -> Fill Time
I've had really strange delays in WOT shifts and randomly in other spots (very obvious in WOT shifts). Reducing this when increasing the shift pressure seems to have helped here. I suspect too long of a fill time causes the transmission to attempt to reduce or "bleed" the pressure before the shift actually happens causing a really long delay that can be felt. 100ms seems okay here across all temperatures so far. I haven't tested in cold weather yet, this will have to come in the winter months.

Shift Pressures -> Downshift -> Oncoming Clutch
This is named backwards and might actually consider this a bug in HP Tuners or the ZF naming scheme is just strange. I've successfully zero'd out all these tables and the shifts have all improved. Most notable is 3-2 and 2-1 downshifts near idle. The ECU seems to keep the RPMs from dropping so holding the clutch on the downshift isn't needed IMO.

Shift Pressures -> Downshift -> Offcoming Clutch
Like above, this is named backwards and might actually consider this a bug in HP Tuners or the ZF naming scheme is just strange. I've gone and increased all these pressures by 20% without issues. The stock pressures are too weak if you downshift with the torque converter unlocked IMO. I've reduced the pressure around idle shifts by 50% to smooth out the downshifts. There is little to no "bump" felt now.

Good information! I look forward to continuing! I'm trying to set up thanks to you ZF8HP55. I feel that sometimes I am on the right path, but I do not fully understand and the result does not bring results.

[ic3man5]

Thanks! I just reset all the transmission parameters to stock and realized I'm not actually resetting the adapts as much as I thought I was. The scanner seems to do a little bit to reset the adapts but its not a complete reset. I had a 1-2 shift I couldn't get the aggressiveness out and its now finally gone after 100+ miles of driving on the stock parameters. I've done every reset I could find in the scanner. I don't think we have the ability to do a 100% reset of the adapts and I haven't found a setting to disable adapts.

I do need to figure out how to detune/disable the aggression mapping as that will push your tune over the edge as I found out after having to drive to the hospital extremely fast the other day.