Major Shudder over speed bumps

[ahuyghe]

Hello:
I'm hoping someone out there can help me on this ....

I am driving a 2007 STS4. I have had the transmission shudder at low speed repaired, but still seems to read it's ugly head now and then, but what has bothered me for quite some time is a major shudder through out the car when passing over speed bumps at low speed.

If you pass over the Speed bump at low speed with your hand on the shifter, the shudder is unmistakable, and you can feel it throughout the car, almost as though the transmission is going to fall out. I have never owned a vehicle that does thi...ever. I mean you can expect some suspension bounce etc, but the entire drivetrain seems to move quite violently. Has anyone else experienced this?

Thanks

Al

[dkozloski]

Originally Posted by ahuyghe

Hello:
I'm hoping someone out there can help me on this ....

I am driving a 2007 STS4. I have had the transmission shudder at low speed repaired, but still seems to read it's ugly head now and then, but what has bothered me for quite some time is a major shudder through out the car when passing over speed bumps at low speed.

If you pass over the Speed bump at low speed with your hand on the shifter, the shudder is unmistakable, and you can feel it throughout the car, almost as though the transmission is going to fall out. I have never owned a vehicle that does thi...ever. I mean you can expect some suspension bounce etc, but the entire drivetrain seems to move quite violently. Has anyone else experienced this?

Thanks

Al

Slow down. That's what speed bumps are for.

[next2pool]

Noise and Vibration complaints are very difficult to evaluate on line for obvious reasons, but let's talk through this a bit. Between the engine, trans and differential, there is a lot of mass bouncing around. The mounting of those is always a tradeoff between isolation and enough control. The shifter is one of the main feedback connections on the STS and a lot of people complain about it--partially because it's a natural place to rest your hand. There is some level of adjustment that may help. I would get the car on a hoist and carefully check the engine, trans, and differential mounts for looseness or ground outs. Since your vehicle is almost new, I doubt you have any broken mounts, but you never know. I would also look closely at the cradle mounts to make sure non are loose. Based on my experience with just a RWD version, I'd have to say this is not normal.

[jmyrick]

My 06 rwd does the same thing.

[CStradling24]

There is a service bulletin for a software update where the rear suspension is over compensating for bumps at slow speeds. Its described as a groaning sound. You may also need a clutch pack or a fluid flush in the rear diff. All of this has been done to my 05 under warranty and problem solved. If someone has access to AllData they could post that bulletin.