07 Yukon Transmission Hammering/hard Shifting issues

[cjsly172]

Hi all,

I had my transmission serviced (fluid flush) last June on my 2007 5.3L GMC Yukon. At the time it had approximately 55k miles and today has 64k miles. A few months later I started to experience very random transmission issues that have recently become more persistent. The first issue is the transmission seems to hammer when the car rocks back when coming to a normal stop (It doesn't always do it when you come to a very slow stop). Once it has hammered after the stop, it will do it again within a second or so after accelerating.

Now it seems to be occasionally shifting hard between first and second and/or second and third gear. I have stepped on the gas a few times to experience either a hard shift or an initial dogging of speed until I get in an upper gear.

Has anyone had a similar experience? What did you do to resolve this?

 

[KMeloney]

Adding a bump (no pun intended) here, since my '09 has started to make a noise during more-pronounced hard shifting.

 

[gitrduun]

Take it to gm, get your warrantys worth

 

[cjsly172]

I am out of the 5 year...even though mileage is really low.

 

[GM Customer Service]

Hi all,

I had my transmission serviced (fluid flush) last June on my 2007 5.3L GMC Yukon. At the time it had approximately 55k miles and today has 64k miles. A few months later I started to experience very random transmission issues that have recently become more persistent. The first issue is the transmission seems to hammer when the car rocks back when coming to a normal stop (It doesn't always do it when you come to a very slow stop). Once it has hammered after the stop, it will do it again within a second or so after accelerating.

Now it seems to be occasionally shifting hard between first and second and/or second and third gear. I have stepped on the gas a few times to experience either a hard shift or an initial dogging of speed until I get in an upper gear.

Has anyone had a similar experience? What did you do to resolve this?

I'm sorry you are experiencing this issue with your Yukon vehicle. Has the vehicle been inspected for this issue? Any codes? This issue may be due to the 2-4 band apply time extending through the 1-2 accumulator stroke. Another possibility is the accumulator valve sticking in the bore due to chips or debris. These are just suggestions, they are not meant as a diagnosis.

I encourage you to consult with a certified technician for an official diagnosis. They will be able to assist you further after inspecting the vehicle.

Please keep us posted.

Louis
GM Customer Service

 

[Zed 71]

The first issue is the transmission seems to hammer when the car rocks back when coming to a normal stop (It doesn't always do it when you come to a very slow stop). Once it has hammered after the stop, it will do it again within a second or so after accelerating.

Search for the TSB regarding rear end clunk. That might be your issue for this symptom.

Adding a bump (no pun intended) here, since my '09 has started to make a noise during more-pronounced hard shifting.

Does yours have the 6L80E tranny (6 speed)?

 

[KMeloney]

Search for the TSB regarding rear end clunk. That might be your issue for this symptom.



Does yours have the 6L80E tranny (6 speed)?

I'm not sure just yet, but my clunk sounds like it's coming from the front of the truck, not the rear.

And yes, I have the 6-speed. Have I mentioned lately that I hate it?

 

[Zed 71]

And yes, I have the 6-speed. Have I mentioned lately that I hate it?

Ahhhh I remember you trying to adjust it with a tranny tune. I have not been on here for a while.