4L80E Tuning Assistance

[TransGo Robert]

The hub of the converter kind of slips into the flex plate- the holes match size.

Correct, it needs to float int here and move back and forth with the flexplate absorbing the energy or else the pump would break.

And the distance from the bolt area to the hub is the bending or torque apply force, e.g. when the bolts are farther away from the center of the flex plate, there is more bending or torque applied at the center.

Actually I found what I Was looking for I think this is what I am imagining
Attachment 137659
https://www.atesteo.com/en/flexplate/

The flexplate is simply a spring, it is there to absorbed and store the energy that makes the converter move forward towards the engine up until the the point where internal clearance of the converter components is taken up. It does not multiply in anyway the force applied to the crank or pump, it simply allows for movement in both direction.

[kingtal0n]

Thanks. For anyone following I found this as well
https://ls1tech.com/forums/automatic...l#post19292425


And this

From "Powerglide Transmission Handbook" by Carl H. Munroe:

p. 54: In addition, the oil pressure in the converter forces it forward. This action can be compared to a hydraulic jack. Converter charge pressure from the transmission enters the converter and pushes it forward toward the engine. In stock applications, the thin flexplate isolates this movement from the thrust bearing. Race applications often use heavy duty flexplates that will not "give"; in these instances, minimizing flow restrictions through the converter will maximize thrust bearing life. The problem is greatly aggravated should the cooler lines or cooler become restricted. Any restriction in the cooler or lines restricts fluid flow from the converter.

https://forums.maxperformanceinc.com...0&postcount=54

Ofc I am using a 'stiff' SFI flex plate and a lube-to-line PR valve from Sonnax.

I think... I think I will try to measure my cooler return line pressure and take a second look at how its routed. If anything that is something I learned is more important than I Realized. Thank you

[TransGo Robert]

Thanks. For anyone following I found this as well
https://ls1tech.com/forums/automatic...l#post19292425


And this

https://forums.maxperformanceinc.com...0&postcount=54

Ofc I am using a 'stiff' SFI flex plate and a lube-to-line PR valve from Sonnax.

I think... I think I will try to measure my cooler return line pressure and take a second look at how its routed. If anything that is something I learned is more important than I Realized. Thank you

This is not a 400, it is a 4L80E, quite the different animal. In a 4L80E you have the converter limit valve that prevents converter charge pressure from ever going too high when not in lock-up no matter what line is or if it has line to converter charged drilled or have that valve you have in there which does the same as the hole.

Once it locks up, the pressure is then regulated by the TCC regulator valve also limiting it to a safe level. Cooler line pressure will only give you an relative idea of what the converter charge pressure might be when out of lock-up (in lock-up it is no longer related to converter charge pressure) but it is not going to be as high as the actual converter charge pressure since it is downstream of an orifice.

[kingtal0n]

That leaves me wondering what the difference is when commanding higher and higher TCC PWM % since the regulator valve is just going to clamp it off anyways apparently. It seems like there may be a chance that 80% and 99% PWM give the same final converter pressures for example once line pressure is past a certain point. I guess it isn't possible to know the converter pressure in lockup using a typical measurement from outside- however there are tables for TCC apply that increase line pressure for the Lockup situation, which makes me think that a percentage of the pressure during lockup is a percentage of total line pressure supplied by the EPC. For example the TCC can slip with 100% PWM and 150psi of line but doesn't slip with 80% PWM and 200psi of line. The PWM is only a part consideration of converter pressure that holds the clutches from slipping.

[TransGo Robert]

That leaves me wondering what the difference is when commanding higher and higher TCC PWM % since the regulator valve is just going to clamp it off anyways apparently. It seems like there may be a chance that 80% and 99% PWM give the same final converter pressures for example once line pressure is past a certain point. I guess it isn't possible to know the converter pressure in lockup using a typical measurement from outside- however there are tables for TCC apply that increase line pressure for the Lockup situation, which makes me think that a percentage of the pressure during lockup is a percentage of total line pressure supplied by the EPC. For example the TCC can slip with 100% PWM and 150psi of line but doesn't slip with 80% PWM and 200psi of line. The PWM is only a part consideration of converter pressure that holds the clutches from slipping.

99% is going to yield more converter charge pressure then 80% for as long as the solenoid is not maxed out in it's physical ability to flow. That limit will simply be reached sooner if line is higher.

By the way you can eliminate any of those worries by simply using our 4L80E-TCC Kit https://transgo.com/product-details/4l80-tcc-regulator/ and setting it up with the optional full ON/OFF option. That takes the solenoid and computer completely out of the equation and limit the converter pressure to a safe level no matter what line does.

[TheMechanic]

99% is going to yield more converter charge pressure then 80% for as long as the solenoid is not maxed out in it's physical ability to flow. That limit will simply be reached sooner if line is higher.

By the way you can eliminate any of those worries by simply using our 4L80E-TCC Kit https://transgo.com/product-details/4l80-tcc-regulator/ and setting it up with the optional full ON/OFF option. That takes the solenoid and computer completely out of the equation and limit the converter pressure to a safe level no matter what line does.

Wow that's nice. Only $40. That's a must do mod.

[kingtal0n]

99% is going to yield more converter charge pressure then 80% for as long as the solenoid is not maxed out in it's physical ability to flow. That limit will simply be reached sooner if line is higher.

By the way you can eliminate any of those worries by simply using our 4L80E-TCC Kit https://transgo.com/product-details/4l80-tcc-regulator/ and setting it up with the optional full ON/OFF option. That takes the solenoid and computer completely out of the equation and limit the converter pressure to a safe level no matter what line does.

Yeah thats kinda what started all of this. I recently went through my trans @ 25k and everything looks great and I changed to a slightly higher stall SS3200 Yank converter and was thinking what else I could do while in there. But its already back in the car for now and I am *sick* of transmission stuff for a while. Until the bumps on my head and cuts on my hands heal up for a while anyways. Getting a 4l80e onto a jack under the car is nothing to laugh about, well maybe hysterically while crying.

Thanks for all your input its been superior to anything else I read so far online even from people that build these transmissions for a living. I wonder what you think about the no-walk bushing backwards and the triple plate jingle at neutral- the plates stop making noise in gear, I worry that means they are being applied slightly. But everybody so far says that is 'normal'. Do you think they should still jingle in gear? Do I need a larger lube-to-line ? Just wondering it seems fine there is no drag.

[TransGo Robert]

Yeah thats kinda what started all of this. I recently went through my trans @ 25k and everything looks great and I changed to a slightly higher stall SS3200 Yank converter and was thinking what else I could do while in there. But its already back in the car for now and I am *sick* of transmission stuff for a while. Until the bumps on my head and cuts on my hands heal up for a while anyways. Getting a 4l80e onto a jack under the car is nothing to laugh about, well maybe hysterically while crying.

Thanks for all your input its been superior to anything else I read so far online even from people that build these transmissions for a living. I wonder what you think about the no-walk bushing backwards and the triple plate jingle at neutral- the plates stop making noise in gear, I worry that means they are being applied slightly. But everybody so far says that is 'normal'. Do you think they should still jingle in gear? Do I need a larger lube-to-line ? Just wondering it seems fine there is no drag.

I totally understand and you are very welcome.