Torque Converter or Transmission

[Brian1133]

I have a 2014 tahoe with the 6speed transmission. At times my transmission will act like it goes neutral under moderate to hard acceleration, I would have to let off the gas to snap back in. The first time I noticed it was on a 10 hour drive from MD to Nashville and my truck had about 25,000 miles. I accelerated hard from a stop, and around 60mph @ 3500rpm it revved to 6000rpm, let off the gas and then kicked into gear no codes or anything. As I drove more over the years on the highway, it became more prominent. Now I can be riding about 50 and hit the gas moderately it will rev like it's in neutral sometimes til I let off the gas, or get into gear but as if someone was letting go of a clutch (for the old guys like me that used to drive a stick). I'm driving more on the highway nowbeen and it's starting to bother me, albeit it hasn't done it in about a week. I have 170,000 miles on my truck. No one has ever able to find out what the issue is. Does anyone have any experience with this on the 6speed 5.3?

 

[B-train]

What is the service history? Have you kept an eye on the fluid level? These may not be the issue at hand, but needed info nonetheless. I'm going to say torque converter based on the actions and the fact that these transmissions seem to have an inherent fail date. Either way, you're looking at a bigger job. If you catch it before failure and it is the torque converter, then you can save yourself some money before the whole trans is shot. But, with the number of miles, it may be time for a GM Certa trans if you like the truck and want to keep it.

 

[Geotrash]

I have a 2014 tahoe with the 6speed transmission. At times my transmission will act like it goes neutral under moderate to hard acceleration, I would have to let off the gas to snap back in. The first time I noticed it was on a 10 hour drive from MD to Nashville and my truck had about 25,000 miles. I accelerated hard from a stop, and around 60mph @ 3500rpm it revved to 6000rpm, let off the gas and then kicked into gear no codes or anything. As I drove more over the years on the highway, it became more prominent. Now I can be riding about 50 and hit the gas moderately it will rev like it's in neutral sometimes til I let off the gas, or get into gear but as if someone was letting go of a clutch (for the old guys like me that used to drive a stick). I'm driving more on the highway nowbeen and it's starting to bother me, albeit it hasn't done it in about a week. I have 170,000 miles on my truck. No one has ever able to find out what the issue is. Does anyone have any experience with this on the 6speed 5.3?

My take is that something is releasing the hydraulic pressure on one of the clutch packs, causing it to disengage. If it were the TC, I wouldn't expect it to fully disengage the drive because it's essentially a turbine so it can't release the torque instantly like that. My money is on one of the pressure regulators in the valvebody being defective from get get-go. Time to get that transmission out though and have it rebuilt properly.

 

[Foggy]

Def not torque converter imo... Your trans is on it's way out, even if just low
on fluid ;it sounds like it's been acting like this for a while
No info on mileage/usage/ service history/ etc as of this point

 

[Brian1133]

What is the service history? Have you kept an eye on the fluid level? These may not be the issue at hand, but needed info nonetheless. I'm going to say torque converter based on the actions and the fact that these transmissions seem to have an inherent fail date. Either way, you're looking at a bigger job. If you catch it before failure and it is the torque converter, then you can save yourself some money before the whole trans is shot. But, with the number of miles, it may be time for a GM Certa trans if you like the truck and want to keep it.

So I've changed the filter and fluid just about every 45,000 miles and I have no leaks. What's a Certa Trans? I want to keep my for as long as I can.

 

[Brian1133]

What is the service history? Have you kept an eye on the fluid level? These may not be the issue at hand, but needed info nonetheless. I'm going to say torque converter based on the actions and the fact that these transmissions seem to have an inherent fail date. Either way, you're looking at a bigger job. If you catch it before failure and it is the torque converter, then you can save yourself some money before the whole trans is shot. But, with the number of miles, it may be time for a GM Certa trans if you like the truck and want to keep it.

Thanks, how much should I be saving up? Last time I bought a transmission, not sure what brand, I paid 3600 for a new one with 36,000 warranty for my wife's 5 speed explorer from an independent shop. The new one went out a few weeks before the warranty expired so I really lucked out. But I'm sure it wasn't a ford tranny.

 

[Geotrash]

So I've changed the filter and fluid just about every 45,000 miles and I have no leaks. What's a Certa Trans? I want to keep my for as long as I can.

Certified. GM offers a fantastic warranty on their certified transmissions that can be used at any GM dealer.

 

[Geotrash]

Thanks, how much should I be saving up? Last time I bought a transmission, not sure what brand, I paid 3600 for a new one with 36,000 warranty for my wife's 5 speed explorer from an independent shop. The new one went out a few weeks before the warranty expired so I really lucked out. But I'm sure it wasn't a ford tranny.

For a dealer-installed GM certified transmission you're looking at around $5-5.5K. My local indy transmission shop here that does really good work quoted me $3.5K for a rebuild on my 2007 including an upgraded billet TC. Fortunately I don't need it yet, but it's good to know the price anyway.

 

[Just Fishing]

I'm curious about this.
Does it do it in all gears or just one?

Off the top of my head, it sounds like the "1-2-3-4 drum or piston has a crack in it.
burns clutch out, confuses rebuilders.
It's good times!

 

[Just Fishing]

6l80E Transmission Problems

www.transmissionrepaircostguide.com

Cracks in the 1-2-3-4 piston​

Early versions of this transmission are known to develop cracks in the 1234 piston and sometimes in the piston itself. Transmission re-manufacturers like Street Smart Transmission will install an updated 6L80 1234 piston and housing to properly correct the problem.

Cracked drum​

Many times, 3-5-R clutch problems and failures can be traced back to a failed drum weld. Many rebuilders will simply weld the cracks, but that generally leads to more issues later on. Transmission re-manufacturers like Street Smart Transmission will install an updated 6L80 clutch drum to properly correct the problem.

4-5-6 clutch hub and intermediate shaft​

Due to issues with the original manufacturing process, cracks and other damage can cause a catastrophic failure of the 4-5-6 clutch pump and intermediate shaft. These common 6L80E transmission problems are very serious and can obviously cause a number of serious drivability issues. This is why remanufacturing companies often upgrade these components.

Low sprag failure​

When the vehicle starts off in first gear, it may feel as if the transmission has shifted into neutral because the low sprag is failing and the low/reverse clutch is the only thing holding the output carrier stationary during first gear.

Stator support shaft cracking and failed seals​

One of the most common 6L80E transmission problems is the failure of the stator support seals, and cracking of the stator support shaft. These issues can cause problems like delayed shifts, harsh shifts and clutch failure. Remanufacturing companies like Street Smart Transmission inspect each stator support shaft for signs of damage, then install upgraded seals to solve the problem.

 

[Just Fishing]

^ If it's just first gear, it sounds like a low sprag failure.

I'm also curious if using tow mode helps or not.

 

[Just Fishing]

Re-read this.
since you mentioned a speed that rules out first gear I searched a little.
Sounds almost like when the transmission goes into a fast learn.

Found this: https://forum.hptuners.com/showthread.php?79917-6L80E-TCM-random-disconnect-at-WOT-drops-in-neutral

Possible cause electrical!
"Power wire from the alternator that goes by the head got really close to the header and was randomly arcing"

 

[Doubeleive]

Thanks, how much should I be saving up? Last time I bought a transmission, not sure what brand, I paid 3600 for a new one with 36,000 warranty for my wife's 5 speed explorer from an independent shop. The new one went out a few weeks before the warranty expired so I really lucked out. But I'm sure it wasn't a ford tranny.

about $4k and take it to the best shop in town. a experienced rebuilder should get it done right and it will be less than what the dealer will charge.
tell them you want a billet torque converter & rebuild.

 

[Charlie207]

Every time I read one of these threads my anxiety starts spiking.

 

[Just Fishing]

Due to it going into "N" when WOT and at speed.
I'm leaning towards an electrical issue like a short/grounding issue.

These are clutch to clutch transmissions.
valve body and computer controls everything!
If the TCM was to shut down suddenly it makes sense that the cutches would release.

In the one link, it showed he was doing data logging and the data from the TCM froze when it happened.
Suggesting the TCM shut down and possibly rebooted.

I also wonder if the op also has an engine/transmission mount that failed.
Allowing the engine to rock and bam short or ground getting pulled!

 

[Tozan]

I just had mine rebuilt with a new TC the cost was around $4300.

 

[Plimbob]

I had mine rebuilt with Billet TC, Sonnax valves and the updated thermostat = $5,200.00.

 

[Just Fishing]

Parts all by itself when I did my own with a new pump (stator housing, bell housing, and pump) w/ a circle d 6l80 double disk converter ran me about 3k

that included some proactive replacements, all new bushings, clutches, 90% new steels, bearings, seals, sonnax upgrades like the heavy duty 6 gear piston, sonnax billet piston upgrade for the 1-2-3-4 + proactive replacement of that drum @ $250, I also sprung for the "Blue" heavy duty pistons.

before that I had already gone through the valve body, rebuilding the pressure switches, and upgrading everything with a transgo shiftkit + all of their extras.
Part of that kit I had upgrades for the transmission pump when I did the actual rebuild.

I thought it was an easy transmission compared to the first/last automatic I rebuilt, a 700r4/4l60.

Also, to note my transmission didn't fail, it was more of a proactive rebuild while it was easy to get to.
So, I didn't have much wrong with it.
It just needed the basics, updates, and upgrades that I saw fit to use.

I did have a broken wave plate in my 2-6 clutch pack, apparently that's somewhat common.
No signs that there might have been an issue before tear down.


I can see these getting expensive to rebuild once you add in labor for removal, install + the time it took to blue print the fk out of it.
Like getting the clutch pack clearances perfect, endplay within spec, testing, etc.
But man, what a pleasure to rebuild that transmission was.

 

[Swaggerwagon]

For a dealer-installed GM certified transmission you're looking at around $5-5.5K. My local indy transmission shop here that does really good work quoted me $3.5K for a rebuild on my 2007 including an upgraded billet TC. Fortunately I don't need it yet, but it's good to know the price anyway.

Would your 2007 have the six speed trans?

 

[Geotrash]

Would your 2007 have the six speed trans?

Yes, it does. The Denalis got the 6L80 in 2007.