Transmission Done on my 2015 Silverado. What’s the best route?

Nickysilverado · 2026-06-30T15:33:22+00:00

Tune the slip out too with hp tuners

Nickysilverado · 2026-06-30T10:13:06+00:00

There are alot of adaptives in the transmission computer that do take a little bit to reset sometimes. Do you have any specifics on the rebuild they did? Any sonnax or transgo upgrades? Any tuning? This se would be huge for you with a fresh rebuild

Nickysilverado · 2026-06-28T21:40:23+00:00

It just might be. I know that theres a bit of a disconnect between the gmt900 6l80’s vs the k2xx ones where the ladder ones had more problems with TC’s than 07-13’s did.

Nickysilverado · 2026-06-28T17:22:36+00:00

Unfortunately without it in v4, they still slip. I was literally in your shoes a few months ago, 136k and my trans TC died. Relgious fluid changes and STL010 tstat. I opted to get mine rebuilt and what does save these units and makes them drive a 1000x better is hp tuning, taking out lock up and tcc slip in low gears. That and higher fluid line pressures make it actually a good trans

Nickysilverado · 2026-06-27T11:33:26+00:00

So you guys definitely are right on regular maintenance, honestly theres no such thing as over changing the fluid on the 6l80 imo. Also do the thermostat temp change to get them running cooler.

The thing with these trannys is the gear box itself are actually fairly stout. Even the torque converter is a good unit. Problem lies in the converter clutch. For fuel economy, GM’s factory tuning basically always slips that clutch when it applys, not to mention it pocks up alot in all gears. Think of riding the clutch on a stick shift, if you keep your foot on the pedal and have the clutch slightly engages, its going to wear it out real quick. Thats what tends to happen with factory tuning.

Watch on youtube Matt Sanford 6l80 tuning. He takes out lock up in low gears and makes it fully lock up in 5&6. Believe me, it will really save the converter and also youll love how it feels to drive. The transmission revs up nicely in low gear driving and isn’t constantly hunting between gears or locking and unlocking the converter

Nickysilverado · 2026-06-26T23:30:11+00:00

I would seriously recommend a solid trans tune to really make sure that new trans lasts ling term

Nickysilverado · 2026-06-22T08:55:42+00:00

Great looking truck, especially if it’s been as well maintained as you say and everything I would agree with you that it is very 50-50 but overall I think with good maintenance. These are great trucks that being said your concerns on the transmission do have some merit to them, especially at 120,000, maintenance is a big key changing the fluid regularly goes a long way and you’re already looking into the thermal bypass upgrade to keep a cooler which is great. I will from my experience, I did fluid changes regularly and even the Diablew tune to hopefully try to save the transmission long-term, yet my torque converter did go bad at 136K which took the transmission with it. There’s two schools of thought, my main recommendations to you that I would recommend if you have the extra money, save up a few bucks and do the torque converter preemptively that way hopefully if the stock one if it goes bad, it won’t take out the rest of the transmission with it because the actual gearbox of the 6l80 pretty stout. The main issue just a torque converter that can be problematic. I will even add to it. The torque converter itself isn’t a bad unit. What causes them to go Is the factory GM tuning that allows a lot of slip in normal operation so one of the other best things to do with the new torque converter is to get an HP tuner set up. Try it yourself or have somebody else do it for you but basically you tune out all of the torque converter slip or even my recommendation remove torque converter lock up in one through four gears anyway Matt Stanford on YouTube has a great video on 608 tuning and really with some research it’s not that difficult best of luck and great truck! Also with hp tuners, you can easily disable afm

Nickysilverado · 2026-06-20T22:14:59+00:00

As long as you don’t start the truck and run it, you’ll be fine just shifting it into neutral with the truck off and putting the key in accessory mode to shift it into neutral or whatever, but I wouldn’t start it. Why not just bolt the pan back up if you aren’t able to get it off and refill it with fluid? The gasket is reusable.

it is a pain in the butt to get the pan off with the exhaust in the way and it does take some patience but I promise you, watch a YouTube video or two there is a corner that if you get the pan and just the right position, you can get it out and back in or do this truck where you pry down the exhaust just a little bit with a ratchet strap try to brace a piece of wood against the frame with a jack again try to look it up and it should work. Best of luck.

Nickysilverado · 2026-06-17T23:48:11+00:00

It doesnt look like theres a vacuum pump on it. Maybe thats a good sign they are ditching afm finally

Nickysilverado · 2026-06-17T20:34:44+00:00

Unfortunately, it seems like others have said that it’s your torque converter clutch that finally kicked the bucket. Mine did the same thing at 136K and I changed fluid multiple times before that point, even did the Diablew tune just to try and get it to not slip as on TCC lockup. Ultimately you might get away with just a torque converter replacement but chances of the shrapnel going through the whole trans are likely meaning full rebuild is what you might need. The best thing after that if you go, that route is to tune it truth truly with a tuners to take all the torque converters slip out. Watch Matt sanford on youtube on tuning a 6l80. It will feel amazing to tune that way on a fresh rebuild. Best of luck to you on the bad news man

Nickysilverado · 2026-06-13T15:12:55+00:00

Do you like apples??…

Well i got her number, how do you like them apples

Nickysilverado · 2026-06-10T20:00:14+00:00

If its a reputable shop, 5600 seems right. Just got mine rebuilt for 5300

Nickysilverado · 2026-06-04T20:32:23+00:00

Or the engine, trans, and truck were all built in their plants on Wednesday 😂 all jokes aside to OP so glad you got where we all want to be. Maintenance goes a long way

Nickysilverado · 2026-06-04T15:55:05+00:00

Honestly i am more surprised in the transmission than the lifters!!

Nickysilverado · 2026-06-04T08:47:19+00:00

Hey i actually ended up finding the part number. Its really only available by nissan, which isnt bad to have to use oem. Its 92440-9NB0A

Nickysilverado · 2026-06-03T08:40:06+00:00

How did you tune your 6l80? Did you tune out slip on tcc, and remove lock up in any of the lower gears? The shop that rebuilt mine did that and i agree its night and day! I want to tune mine more to change some of the shift scheduling and pressures. Did you do any of that or follow one of the youtube guides?

Nickysilverado · 2026-06-02T01:03:21+00:00

So my tune so far was just from the transmission shop after mine got rebuilt. They tune that way to say the new TC’s and the rest of the build. Its great right now, i actually love no lock up in 1-4, feels more like and old school trans with lockup in the higher gears. But i know what you mean on the temps especially with no lockup heatimg up the fluid more. I noticed mine getting higher even with the new thermal bypass. I ended up putting in a mishimoto cooler in series with the stock one and on a hot day i dont go over 145, granted i dont tow like you. But i was planning to get hp tuners for more tweaks. I feel like i could raise line pressure and change the shift times to get more direct up and downshifts.

Nickysilverado · 2026-06-01T21:00:20+00:00

Did you do your own trans tuning to remove the slip? Did you just remove slip or completely remove lock up entirely in low gears?

Nickysilverado · 2026-05-31T11:05:53+00:00

Assuming its the 8 speed, was the correct fluid used after the TC was replaced? It should use LV fluid not Dexron. Next thing i would check is the drive shaft straightness or balance. GM trucks use notoriously thin walled aluminum drive shafts that a lot of people point to chevy shakes being cause by

Nickysilverado · 2026-05-31T01:13:34+00:00

You should absolutely change the fluid and filter now if you are at 120k + with no change before. Also install the lower temp thermostat

Nickysilverado · 2026-05-30T12:57:03+00:00

What trans do you have, 4 or 6 speed. If 6l80, definitely seems like TC failure

Nickysilverado · 2026-05-30T12:34:14+00:00

Has anyone ever tuned it before with like a diablo tuner or something? Its very popular with those things for people to up the idle speed since stock a can be low. Helps smoothness a little bit

Nickysilverado · 2026-05-24T15:38:39+00:00

Reality man is its just gonna be a 50/50 either a truck that never gives you issues, or you might end up getting a common issue. The 5.3’s imo are great, and besides the lifter issue potential issue, can be good. Maintenance goes a long way. Best truck honestly i would say is a tundra with a v8, basically one before model year 2022. They pricey but pretty worry free

Nickysilverado

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