shudders on the highway

I have a 2002 Chrysler Concorde LXI with a 3.5L V6. When I'm on the highway (between 55 and 70mph) the car will occasionally shudder. Usually, it's very subtle and slight, but about twice on any 20 mile trip, it will be very noticeable. This seems to happen either with or without the cruise control on. I have not noticed this at speeds below 55. I do not notice any hesitation when accelerating or when changing gears.

If anybody has a good idea what may be causing this problem, please, let me know.

Thanks, PaulH

Reply to
PaulH
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Check all engine mounts to make sure they are solid, not oil soaked or broken.

Have all wheels checked in a wheel balancer, you may have thrown a weight. They need to check for a busted belt in a tire as well. (will show up as a lump in the tire) You may also have run into a curb and bent a rim. That should show in a balancer if the tech knows what he's doing.

Check all wheel bearings for side-play

Check car for alignment/check for tie rod loosness, both inner and outer.

Check to see that no part of the frame is cracked. (what there is of a frame, of course)

And this is the tricky one:

Have the engine/transaxle checked for proper alignment -in-the-engine-bay-.

The obvious question - has the car ever been in a collision? If it HAS been in a collision then they may not have straightened it back out properly.

Ted

Reply to
Ted Mittelstaedt

No, the car has never been in an accident.

I check (and had checked) all of those items you mentioned. Nothing seemed to be wrong with those.

Any other ideas?

Thanks, Paul

Reply to
PaulH

Yes, one but you won't like it. Put the car in a frame rack and have the frame checked for straightness.

When you have a resonance shudder like this, you have only 3 areas it can be in:

1) The drivetrain, ie: drivelines/axles, transmission.

2) The suspension, alignment & wheels & tires

3) The frame/unibody

You know it's not in the engine because in your lower gears your hitting the same RPM that the car hits in the top gear where the resonance shudder is and your getting no shudder.

And while it could be in the transmission, it's very unlikely since the transmission parts that spin at the output RPM that this shudder occurs in, don't have a lot of mass in the drivetrain.

Now, you are positive that it's not the suspension. Your positive that it's not the wheels or tires. And your positive it's not the alignment.

Thus, the only logical answer is that the car frame is bent.

I personally think that it's in the drivetrain, such as wheels & tires or a bad bearing in the axles. Despite your claim that you checked it, my gut feel is that you missed something.

Ted

Reply to
Ted Mittelstaedt

This post looks old but if you have not found a solution I suggest the inner tie rods. These are a bear to get to and expensive to have done. It is hard to see if they are bad because the cover plate hides the ends. It solved my problem which sounds a lot like yours.

Reply to
peedeesuave

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