6R80 3-4 Shift Flare

[Spooled]

Yeah. I'm not sure exactly what I changed on that one.. I'll have to go back through my notes. I think I upped offgoing and oncoming pressure some more. Like a lot. Not exactly sure how far you can safely up the values though...

[CKrueg]

I think you can increase them as much as you want, until it starts to slam into gear, or the solenoids can't increase pressure anymore. I agree, looks like they crossed at a higher pressure. Not sure if you've tried it but I would increase boost pressure and time. For the Off going element

[gilgamesh]

I think there's a general pressure limit you might end up needing to increase as well. I've seen some people up that from 150PSI to 250PSI.

[Spooled]

This one was a little better yet. Upped the Boost pressure on Element D some more. It flared a little bit still, but finally making some progess. 8.JPG


Now, I have a question. Does anyone the know the relationship between Clutch fill time and oncoming/offgoing pressure? Say the shift is demanded and your clutch fill time is .500. Does the trans shift after .500 goes by regardless of if the desired oncoming/offgoing pressure is met? I guess I'm thinking in my head the clutch can only fill so fast. If you let it fill all the way and meet desired pressure the shift should be better correct? Or am I thinking it wrong?

[gilgamesh]

I think you are thinking correctly. From what was described here it sounds like some slip will happen if the clutch is not allowed enough time to fill.
https://forum.hptuners.com/showthrea...l=1#post454845

[CKrueg]

The way I understand it, clutch fill time is the time before the oncoming clutch begins to ramp up. So if it is too short, the oncoming will apply to before the Off going is released. If its too long, the oncoming will ramp up slowly/later causing a soft shift.

[gilgamesh]

That makes good sense CKrueg.

I found this image and thought it might be helpful for referencing the clutch sequence. It's not ford specific and doesn't contain boost but it sure looks familiar from looking at our logs.
ShiftDiagram.PNG

[murfie]

You need to log engine brake torque, so that you can make sure you are making changes in the correct spots. With things like TQ source trans shift mod happening you might be applying changes at the 410ftlb when really it is using the 110ftlb line. Input shaft and output shaft speeds are good. Line pressure is good as well, it gives you an idea of the pressure the clutches are seeing.
Your shift solenoid pressures are not the pressures the clutches are seeing. They only control latches and regulator valve positions. Those control the pressure to the clutches. So you will not see oncoming, offgoing, boost pressures in the log for each clutch.
If you pick up a 6r80 service manual you can see how the solenoids control the latches and regulators and control pressures. Its a lot to study and quite complicated, but needed.

Clutch fill time is the time it takes to fill the off going clutch circuit with low pressure once the high regulated pressure is removed. If this is too short the clutch is not fully disengaged and you can get RPM drag when the ramp on the oncoming clutch happens.

In your case B is off going and E is on coming for a 3>4 shift. solenoid D controls pressure to clutch E when solenoid E turns on. Solenoid E is just and on/off and positions the latch and regulator that D is controlling, whether it is low/reverse or 4,5,6. It would be nice to log just to make sure its not lagging behind, but you might need support to add it to your scanner.

[CKrueg]

You need to log engine brake torque, so that you can make sure you are making changes in the correct spots. With things like TQ source trans shift mod happening you might be applying changes at the 410ftlb when really it is using the 110ftlb line. Input shaft and output shaft speeds are good. Line pressure is good as well, it gives you an idea of the pressure the clutches are seeing.
Your shift solenoid pressures are not the pressures the clutches are seeing. They only control latches and regulator valve positions. Those control the pressure to the clutches. So you will not see oncoming, offgoing, boost pressures in the log for each clutch.
If you pick up a 6r80 service manual you can see how the solenoids control the latches and regulators and control pressures. Its a lot to study and quite complicated, but needed.

Clutch fill time is the time it takes to fill the off going clutch circuit with low pressure once the high regulated pressure is removed. If this is too short the clutch is not fully disengaged and you can get RPM drag when the ramp on the oncoming clutch happens.

In your case B is off going and E is on coming for a 3>4 shift. solenoid D controls pressure to clutch E when solenoid E turns on. Solenoid E is just and on/off and positions the latch and regulator that D is controlling, whether it is low/reverse or 4,5,6. It would be nice to log just to make sure its not lagging behind, but you might need support to add it to your scanner.

So does that mean that when the pressure for solenoid D starts increasing in the log above, that is essentially sending the line pressure to clutch E? and when the pressure of solenoid B is reduced it is taking the high pressure fluid off of clutch B?

[Spooled]

I added engine brake torque to the log. Here is a screen shot


Murf - it doesn't look like I can currently log clutch E currently.

[gilgamesh]

Send a support ticket - maybe they'll include it someday. I've been waiting a year for the 6.7 PIDs to be even close to what you've got available.

[Spooled]

Should the oncoming clutch be ramping up before the offgoing starts releasing? I feel like this is also part of the problem, but I haven't been able to change anything to make this any better



If there are any experienced 6R80 tuners lurking in here, I will pay you to take a look at my tune and get these shifts better. They are killing my acceleration and performance. Just shoot me a PM and we can work something out.

[murfie]

So does that mean that when the pressure for solenoid D starts increasing in the log above, that is essentially sending the line pressure to clutch E? and when the pressure of solenoid B is reduced it is taking the high pressure fluid off of clutch B?

Yes. service manual is a must have to understand any of it.

Should the oncoming clutch be ramping up before the offgoing starts releasing? I feel like this is also part of the problem, but I haven't been able to change anything to make this any better

That is normal. All gear shifts from 1st to 6th or from 6th to 1st are power-on overlapping shifts. That is, during the shift, one of the clutches must continue to transmit the drive at lower main pressure until the other clutch is able to accept the input torque.

No need to scan for solenoid E. Don't bother support. Its only an on/off, and 4th and above it is on, 3rd and below it is off.

[Kcc0521]

I think I am having the same issue with one of the larger names tuners out there using SCT. I bought HP tuners and I plan to try it myself. I added 2lbs of boost to my car and the rpm ramp appears to show some slip and it is not tire slip. My tuner said he thinks it is the clutches but I am not so sure. What should I log to help diagnose it?

[veeefour]

I had the same problem but for 2-3 and 4-5 (B clutch Oncoming) - was able to solve it. I can now force the trans to RPM flare at any gear, 2-3, 3-4 doesn't matter.

Asked OP to post a tune before but tunes are secret as we know You can also PM me your tune - problem is in ramp rates.

And BTW I believe they are named incorrectly in HPT. Oncoming should be named 2M-3M, 3M-4M not 3M-2M, 4M-3M - or they are swapped?

Anyways, you have to match the ramp rates for oncoming and offgoing - the RPM flare is when one clutch is engaging too fast at the other is disengaging too slow.
Or the other way around. RPM flare can happen either during up or down shift. You have to ramp the off-going clutch slower compared to on-coming.

Hope it makes sense.

[Spooled]

I had the same problem but for 2-3 and 4-5 (B clutch Oncoming) - was able to solve it. I can now force the trans to RPM flare at any gear, 2-3, 3-4 doesn't matter.

Asked OP to post a tune before but tunes are secret as we know You can also PM me your tune - problem is in ramp rates.

And BTW I believe they are named incorrectly in HPT. Oncoming should be named 2M-3M, 3M-4M not 3M-2M, 4M-3M - or they are swapped?

Anyways, you have to match the ramp rates for oncoming and offgoing - the RPM flare is when one clutch is engaging too fast at the other is disengaging too slow.
Or the other way around. RPM flare can happen either during up or down shift. You have to ramp the off-going clutch slower compared to on-coming.

Hope it makes sense.

I'll PM you the tune when I get my truck back up and running. I've been away for work and had a fuel system issue arise and had to turn the boost down. Changing up the fuel system this weekend hopefully.