[jpiltin]

I have an '11 STS V6 RWD w/50k miles. Last week I started noticing a harsh clunk or bang when releasing the accelerator, slowing slightly then light to mid reacceleration. I've been trying to find a way to drive without causing this until I find a fix but it happens frequently. I inspected all mounts, bushing, flex joints, ect today but everything still looks great. I'm almost positive it's in my transmission and wondering if anyone else has experienced this. Any help would be appreciated, thanks.

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[Doctyler2015]

Rear upper differential bushing. They junk and makes alot of noise.

 

[curtc]

Definitely sounds like a differential bushing.

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[Glenn06STS]

Agree with above, and have a question-is there the same clunk when you shift from Park to Drive or Reverse, and/or back and forth from Drive & Reverse? Usually with the upper differential bushing #89058605, you'll hear that least a soft clunk when shifting at rest, before it becomes audible at speed changes.

 

[jpiltin]

Agree with above, and have a question-is there the same clunk when you shift from Park to Drive or Reverse, and/or back and forth from Drive & Reverse? Usually with the upper differential bushing #89058605, you'll hear that least a soft clunk when shifting at rest, before it becomes audible at speed changes.

It doesn't, I did a hard reset (left the batt disconnected overnight) and I'm pretty sure it's back to normal. Tried to get it to happen this am but it was as smooth as ever. I have had to replace PCM's in Lexus's before for similar issues but I haven't had my Caddy long so I'm not familiar with it.

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[curtc]

When my diff bushing was bad it would "buck" back at me during downshifts, along with a very noticeable thud when shifting out of P to R, and from R to D.

 

[jpiltin]

Rear upper differential bushing. They junk and makes alot of noise.

Agree with above, and have a question-is there the same clunk when you shift from Park to Drive or Reverse, and/or back and forth from Drive & Reverse? Usually with the upper differential bushing #89058605, you'll hear that least a soft clunk when shifting at rest, before it becomes audible at speed changes.

When shifting to drive, reverse or power braking I can't hear or feel it clunk. No more than most cars anyway.

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[jpiltin]

Thanks for the help. I've owned my STS for about a year and its been awesome until this, not sure but I'm hoping the hard reset was a permanent fix. If not I'll look into the rear carrier bushing. Thanks guys.

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[Doctyler2015]

Thanks for the help. I've owned my STS for about a year and its been awesome until this, not sure but I'm hoping the hard reset was a permanent fix. If not I'll look into the rear carrier bushing. Thanks guys.

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Good luck. If it works or not. Let us know. Please. I like to know solutions just in case lol

 

[Glenn06STS]

Thanks for the help. I've owned my STS for about a year and its been awesome until this, not sure but I'm hoping the hard reset was a permanent fix. If not I'll look into the rear carrier bushing. Thanks guys.

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If it went away from having the battery disconnected, even for one day, it's not the upper bushing at the differential. When the bushing is shot, it's like a badly worn u-joint or loosely fitted torque tunnel/tube on cars that have them. Any change in driveshaft direction or even change in throttle causes the slack to be taken up with a clunk.