Extreme Vibration during acceleration between 40 and 70 MPH

oldsmobile
silhouette

#1

My 2001 Silhouette started misfiring so I replaced plugs and wires about 7 months ago. Right after all was fine. But over the past 7 months the car has developed a vibration under heavy acceleration between 40 and 70 MPH. There is almost no vibration when I’m not accelerating. There are no ODBII trouble codes. Engine mounts look good. There is no sound but the car shakes so hard that stuff bounces in the cup holders but there is NO vibration in the brake peddle nor in the steering wheel. Could this be a wheel bearing or a bad CV joint? Please help.


#2

Bad inner CV joint would be my first guess. This is a classic symptom. Now, which one…? Start with a boot inspection. If you find one torn with characteristic grease splatter I’d start there.


#3

I’ll bet you hit the nail on the head. My past experience with CV joints wearing out was noise and steering wheel feel at LOW speeds when making sharp turns so I didn’t think of CV joints but after eliminating other items I was beginning to suspect this. I’ve found OLD hard grease near the CV joints but I can’t find any tears in the boots so I assumed it was old spillover from when the dealership put in a rebuilt transmission three years ago. They didn’t replace the CV joints but certainly had to remove and reinstall them. What are the odds that they did something wrong verses the CV just wore out? This car has 160,000 miles. Ann thanks so much for your quick response!


#4

If you’re saying that your half-shafts have 160K miles on them, and/or the transmission install was 3 years ago then there is certainly nothing to wonder about in terms of a bad CV joint. The boots and joints are wear and tear items so they do just go eventually.

There are 2 CV joints on each halfshaft/half axle. A bad outer joint will make noise, especially noticeable on low speed/stationary turning. But an bad inner joint, while it might also make noise, will often show up as acceleration vibration. Bad outer joints are certainly more common b/c they take more abuse.


#5

Cigroller,
You were 100% correct. Changed both half axles and now the ride is smooth again. Thanks very much for your help!