Hello guys, this is a continuation of this thread from a couple of months ago.
I had to rebuild a 2013 6L80 (new clutches, steels, seals, and most bushings, torque converter, Transgo TCC valves, new solenoid pack/ TCM) .

The problem is I've got a bad shift flare on the 2-3 and 3-4 shifts; in fact, I don't even know if I should call it a flare, as it feels almost like the transmission is downshifting for a second or two. The 3-4 shift is especially bad.
Line pressure doesn't make any changes when this occurs.

All clutch packs passed air checks.
The truck does have a code P0121 (Throttle position sensor A circuit performance), but it is not going into "reduced power" mode.

I'd really appreciate any input anyone can give me, as this truck/ transmission has fought me every step of the way (I'll give more details/ warnings later).

 

fix the throttle position code before you diagnose anything with the trans

These are a torque based, synchronous shift, fully computer controlled trans.
If there is anything messed up with the torque modeling (like misfires, throttle position codes, airflow codes, etc) they must be corrected before you try tracking down a trans issue

 

Okay guys, I fixed the TPS issue with a new throttle body; I relearned it accordingly, AND IT'S STILL DOING THE SAME ****.

While I had the scanner hooked up, I looked at the shift times, and the bad shifts were really fast (.10 seconds), whereas the good shifts were about .5 seconds.

One thing I forgot to mention before was that the truck also has a P0011 cam position sensor code (cam isn'tretarding as commanded); I wouldn't think that would cause a shifting issue.

Shift solenoid pressures matched the commanded pressures.
Last of all, when I was assembling the parts, I don't think I aligned the snap ring for the sprag with the blind spline on the hub. My friend with the transmission shop said it doesn't matter. Is he wrong?

I'd really appreciate any help, because I'm running out of ideas.

 

UPDATE: I spoke to my friend about an hour ago, and he said that based on the symptoms, it sounds like the apply piston for the 3-5-Reverse piston probably has a small crack that I missed during the assembly process. He says that he always inspects those with a large magnifying glass; I didn't do that, I just looked it over in the sunlight.

If that's correct, then I have to pull this thing out again, which I REALLY don't want to do.
Please tell me it's something else.

 

more likely that the drum would crack than the 35R piston.
being a 2013 it's less likely than the earlier units but still possible to crack the drum along the weld joint.

If you're convinced this isn't a computer control issue...then at minimum you're pulling the valve body, but more than likely the unit needs to come out for inspection.

 

Well the thing is that I'm not sure it ISN'T a computer issue; this is my first time messing with one of these, and I've never had these complications before.

Are there any other computer issues I should check?
Because I really don't want to take this thing out again.

Thanks for your input.

 

I have seen some similar or odd behavior end up being caused by Compensator Fluid leaks...

 

Okay, Vortec, you've got my attention.
I'll admit that I didn't vacuum check this valvebody because it was originally supposed to be a "weekend job," and as I mentioned in the other thread: IT SHIFTED JUST FINE ONCE THE TRUCK GOT MOVING. Even with all the jacked-up parts inside of it.

I'm not saying that I regret taking on this job, but I'm disappointed with how it's turning out.
I guess I'll pull the valvebody and do a full vacuum check.
I'll let y'all know the results soon.

In the meantime, do you think the cam position sensor code could be causing this? The cam position sensor is not listed as one of the inputs for the TECHM, and it had that code when I first checked the truck.

 

i'm not familiar with this transmissions, but i would be fixing all check engines codes before going any further. i'll admit if its something like EVAP, whatever, but anything powertrain related should be corrected. ive seen transmissions blamed for poor running engines..most recently a friends ford explorer,gutless and left like it was slipping at highway speeds. ended up being a weak fuel pump.

 

Here's an update: I called the tech support line for the company who remanufacters the TECHMs (it's a re-man unit), and the tech over there (actual mechanic? Engineer? Guy who's been there the longest? Who knows.) doesn't think that the P0011 would cause the issue.

Instead, he wants to warranty the TECHM. So they are going to ship one down here, and I'll exchange it, all for free.
I kind of don't think that's the issue, since there are no transmission codes, but I guess it can't hurt.

 

UPDATE: I installed new TECHM, SAME ****.

So I pulled the transmission. Here's what I found:

The 1-2-3-4 balance piston (#412 in ATSG) seal had a chip taken out of it. I have no idea when/ how this happened, because it was not there when I assembled the unit. I'll be getting a new one tomorrow.



Next, I've got two questions:

Which snap ring goes where in the center support for the 2-6 clutches? The ATSG manual has two different ID numbers for them (450 & 455), but they do not give any information on how to identify them, and they can both fit in the same grooves.
One is beveled, the other isn't. I used the beveled ring on top, for the clutches, because that gave me the best clutch clearance.
WHAT IS THE PURPOSE OF THE BEVEL ON THE SNAP RING?



Last of all, I did something a little unorthodox to get my 1234 clutch clearance correct: I cut the friction material off of one side of a clutch plate. This got me within specs.
I know that @MaroonMonsterLS1 is probably slapping his forehead and screaming at his computer right now, but this is where I'm at.

 

I'm really curious if you figured out what the problem is? I'm having a similar problem. My engine sometimes revs between gears, making a hard shift. I first replaced the TCM, then I replaced the transmission...then replaced the ECM...nothing worked! I had a failing fuel pump that was not giving me enough pressure and the shifting issued seemed to get a bit better, but it still happens. I have one more thing to fix: a leaking fuel injector, but I'm not sure that would cause this annoying problem.

 

He showed what the problem was in the post right above your post. The 1-2-3-4 balance piston seal was cut.

 

Couldnt you of swapped snap rings to achieve your clearance here? Just curious on why you went this route?

.085-.089 - yellow marking
.095-.099 - no marking
.106 -.110 - purple marking
.117 - .120 - light blue marking
.127 - .131 - orange marking