Gearbox about to die? Advice welcomed

[Kapitein]

Hello folks,

07 Yukon XL Denali. 175k miles. Car is new to me (purchased a month ago).

Sometimes (and recently more frequently) the gearbox is starting to worry me.

When gently accelerating, the revs on the engine will sometimes fluctuate and jump around at the point I feel like the gearbox should be shifting.... this can be 1-2, 2-3 and 3-4. It can also do this at highway speeds when just cruising along. Normally this would be a torque convertor problem, right?

I also have the infamous clunk at low speeds when letting off the gas, which I presumed to be the slip-yoke. This is on my list of things to do.

The box doesnt always do it. But its getting more frequent.

I have a bluedriver OBD scanner. Zero codes on the motor or box.

Has anybody had this rev jumping issue, it actually makes car rock back and forth, almost like as if you were driving a stick-shift car (badly)!

Advice welcomed

 

[Geotrash]

Hello folks,

07 Yukon XL Denali. 175k miles. Car is new to me (purchased a month ago).

Sometimes (and recently more frequently) the gearbox is starting to worry me.

When gently accelerating, the revs on the engine will sometimes fluctuate and jump around at the point I feel like the gearbox should be shifting.... this can be 1-2, 2-3 and 3-4. It can also do this at highway speeds when just cruising along. Normally this would be a torque convertor problem, right?

I also have the infamous clunk at low speeds when letting off the gas, which I presumed to be the slip-yoke. This is on my list of things to do.

The box doesnt always do it. But its getting more frequent.

I have a bluedriver OBD scanner. Zero codes on the motor or box.

Has anybody had this rev jumping issue, it actually makes car rock back and forth, almost like as if you were driving a stick-shift car (badly)!

Advice welcomed

The valvebodies on the 6L80E have some issues that will cause the behavior that you describe. Luckily, they're easy to repair with a kit on the workbench, with the transmission still in the truck. @swathdiver has all of the details, so hopefully he'll chime in.

 

[Kapitein]

I like the sound of that repair!

 

[Joseph Garcia]

Regarding the clunk, if it turns out not to be the slip yoke, check the differential mounts (2 steel arms with bushings on each side). I replaced my slip yoke, thinking that was the source of my clunk issue, but instead, it turned out to be the differential mounts.

 

[swathdiver]

The valvebodies on the 6L80E have some issues that will cause the behavior that you describe. Luckily, they're easy to repair with a kit on the workbench, with the transmission still in the truck. @swathdiver has all of the details, so hopefully he'll chime in.

I like the sound of that repair!

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GM 6L80 Transmission

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[Kapitein]

That repair kit states the box needs to be removed from the vehicle? Is it possible to leave it in?

 

[swathdiver]

That repair kit states the box needs to be removed from the vehicle? Is it possible to leave it in?

You have to remove the TECHM from the vehicle. You can get to it from the pan, so the transmission does not have to come out.

 

[Kapitein]

Thanks @swathdiver

The second link you posted, linking to the Sonnax website. What exactly should I look to be purchasing from there? The remanufactured valve body?

Thanks

 

[Kapitein]

Would a low fluid level also cause these kind of symptoms?

Im talking 1 to 1.5 qts too low.....

 

[swathdiver]

Thanks @swathdiver

The second link you posted, linking to the Sonnax website. What exactly should I look to be purchasing from there? The remanufactured valve body?

Thanks

The purpose of the Sonnax link was so you can read up on the part mentioned in the first link to Amazon. You can of course purchase a whole new TECHM but they need to be programmed to your vehicle and not sure you can access ACDelco's TDS system in Europe. Just buy the kit and rebuild the solenoids yourself and put the original back in. No programming needed.