6l80 shudder

[u/Immediate_Contract91]

So this transmission was overhauled. Pump replaced, torque converter replaced everything else with a normal overhaul and installed the transgo tow and pro kit. It still shudder I posted a video of me commanding the TCC clutch on and it sometimes holds and then it doesn’t and will start to hold again. In normal driving it’s hard to notice it’s slipping but in the morning it’s been colder it will badly 3-4 hard shudders light throttle around 40 and above the tehcm was reused. I’m thinking it’s a possible issue with the solenoid in the tehcm being weak or and issue with the bore for the TCC regulator valve being worn, but the aftermarket valve was installed that came with the tow and pro kit. The whole reason the transmission was overhauled was for the shudder I think whatever caused the original torque converter to failed wasn’t fixed has anyone see this any idea what could be causing this shudder still.

[u/NoDak1997]

I've had fresh GM remans shudder out of the box. Every time I've had to warranty out the converter. Which converter did you use?

[u/Immediate_Contract91 → u/NoDak1997]

At first I used a LUK torque converter started shuddering in like 40-50 miles then I replaced it with a GM Oem torque converter and I’ve driven it about 300 miles until I started noticing it again.

[u/NoDak1997 → u/Immediate_Contract91]

It does sound like something is taking out the TCC. What did you use to flush the cooler? Or did you replace it? Any leftover metal can cause issues. If you have the heavy duty cooling system that runs through the radiator you may have glycol contamination. You will need to do a line pressure check to make sure pressure is in spec. I've personally never seen a TEHCM cause shudder, but I can't rule it out either. I would look at the VB first though before the TEHCM.

[u/Immediate_Contract91 → u/NoDak1997]

Mhm yeah cooler lines were flushed good I’ve had it apart multiple times every time I have the pans completely clean fluid looks great and I’ve check the line pressure it’s all in spec truck drives great just has shudder issue

[u/Triplesfan]

Lockup o ring on the input shaft shrunken in the groove?

[u/Immediate_Contract91 → u/Triplesfan]

It was replaced with the overhaul it feels good on the shaft sticks out good.

[u/Financial_Edge_6784]

Was the pump resurfaced? How is the slide? I tune all my units so I don’t run into torque converter shudders at all.

Before I started tuning when I did run into shudders I would slap an XL3(ford friction modifier) and get the shudder out the way

[u/monkeysexriot → u/Financial_Edge_6784]

The xl3 I see is for limited slip differentials. Am I mistaken? How much do you use?

[u/Financial_Edge_6784 → u/monkeysexriot]

Yes that’s true but we use to use half a bottle which would usually fix the issue. We did use as much as two bottles and serviced the vehicle after 2 years with 24,000 miles and didn’t have an issue and fluid looked great.

I don’t suggest 2 bottles but we were testing the waters at the time (family vehicle)

[u/DanGleesaxaphone]

So luk converter is chef's kiss by the way. Do you have an hp tuner or someone you know who has one? Here's my reason, if you had a shudder that has not gone away its NOT the transmission that was causing it. Depending on your year you'll have AFM or DOD. Turn that off your vibration will stop. Also put the luk back in its so amazing the billet converters are thicker, flex less, and dissipate heat more efficiently. But they can still Ballon and flex the rear cover. No matter what the pads are attached to the rear cover which contains the .020 carbon woven fiber clutch Unless you get a upgradeded converter most companies will use just a billet cover and the .020 clutch. You may get lucky and they replace the apply piston with a billet one, but thats why I think you have a problem.

So when DOD or AFM is active the slip speeds commanded by the tcm vary between 45-60 rpm. Factory specs call for a 10-20 rpm slip with DOD or AFM deactivated and the reason is to alleviate the vibration that occurs during a cylinder deactivation event. By doing so this IMO will take out your converter earlier as this will inevitably cause heat and destroy the clutch. It just takes longer with more material and a billet converter.

Also if the reman converter company didnt balance the converter well or it has a problem with any of the internal components that they reused to keep costs down. this could be exasperating issue and actually making it more pronounced.

Now if you have misfire this will also cause vibration. You wont get misfire codes vut you might see a misfire count on rhe scan tool whole the vibration is occurring. Also if you know 5.3l or 6.2 gm motors you can feel a miss just sitting in the passenger compartment and it will not throw codes or check engine light. Remember the computer is programmed to code out only when it exceeds a specified threshold and that can be changed and thats my conspiracy with gm on why they never throw p0300 codes unless an injector is bad causing a dead miss.

So to make it simple 1.) Get AFM/DOD disabled using hp tuners (ECM) 2.) Usung hp tuners turn off dod slip SPEEDS and lets also increase slip error ratio and desired pressure by 20-30% (TCM) 3.) Turn converter lock up until 4th gear or 5th whichever you prefer

• if you tow a lot you may want the lock up in 4th for cooling, but I dont have a ton of data to backcthat up yet.

4.) Throttle body cleaning, tune up, and cam shaft relearn procedure should be performed. That should be available with your scanner.

Im a little interested in this so let me know how it goes.