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Vibration under acceleration at freeway speed

8K views 1 reply 2 participants last post by  FusionDiffusion 
#1 ·
OK, I have a 2006 V-6 SEL with 137K on the clock. It had a new (factory refurb) transmission at about 75K and haven't had trouble since then.

Recently, the car has developed a vibration from the drivetrain, but only under acceleration at speeds over 55 MPH or so. From a stoplight up to that speed, no problem. When coasting or just maintaining speed, even up to 80 or 90 or so, no problem. There aren't any noises at any speed or with parking lot maneuvers.

Any ideas? My gut feel says CV joint/axle, but a recent inspection at the dealer didn't catch anything (and I feel sure they'd jump at a chance to sell an axle job). No other driveability issues have been seen.

Thanks for any ideas!

Brad
 
#2 · (Edited)
What happens if you put it in L at freeway speed and coast (this will cause engine braking and a reverse load on the joints)?

CV joints are easy enough to inspect if you jack it up and take off the front wheels. Don't count on them having been inspected. Look for any cracks or tears in the inner and outer boots on each side. They will usually be between the folds and most visible on the outside of the bend where the folds are furthest apart. With the front end in the air you can have someone turn the wheel on the opposite side so you can see all the way around the boots. Make sure the bands are intact and tight. Also grab the axle and pull on it sharply. It should be firm.

Another test is axle play. In park, jack up one wheel (opposite one on the ground) and rotate it CW and CCW by hand until it stops. Note how much rotation you can get. It shouldn't be more than a few degrees.

The problem may also be with the transmission. If you can, try accelerating in different gears to see if it still happens. If it happens regardless of gears then you know it's something in or after the output side of the transmission (like the CV joints).
 
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