Car shakes @ highway speed when accelerating

This seems to be a tricky one. There is a subtle shake to the car when accelerating at city speeds, but when I hit about 60 it really starts to shake. It feels as though it is the front end, and I feel the shake rise through the floor, up the seat, the dash, etc. Stuff in the door well starts to rattle around.

Brought to mechanic. The found some loose bolts on left front suspension and tightened, but shake continued. They checked ball joints, CV, axle\drive train, brakes… all good, no escaping lube. Left front brake heats up more than the others, but that isn’t the issue. Tires have even wear. Can’t figure out what causes the shake. The shake only happens with acceleration. Let off the gas, it stops. Brake, it stops (shaking). Touch the pedal, it starts.

One thing I do notice is a clunking sound in the wheel wells when hitting bumps. Thought it was crappy struts, but that isn’t the case. Mechanic didn’t feel play in the steering components (tie rods, joints etc).

Thoughts? This is a 2007 S60 AWD 2.5T with about 206K miles. Have a Ford Maverick on order since June to replace this, but no idea when I’ll see it.

Based on the acceleration relationship, my guess is some sort of problem in the front drive axles or wheel bearings. Good idea to have your shop check the axle nuts haven’t come loose as a first step. Does the shaking change, or related sounds seem to shift location during turning? If you’ve never replaced the front axles in 206K, I’d probably start there if I had this problem. CV joints can definitely fail even though there’s no grease leaking out. While the half-shafts are out might be a good time to replace the front wheel bearings too. They’re getting to the point where failure isn’t entirely unexpected.

I was going to also say front axels but you say they are good. have them check the wheel bearing on the side that is hotter. also check the motor mounts.

Have someone follow you in another vehicle to see if your vehicle is experiencing tire bounce from a worn strut.

Tester

all good points. I hope they checked the bearings. In terms of struts - had them replaced in spring 2020. I’d say, at most 20K miles. I don’t have the exact info anymore

“Does the shaking change, or related sounds seem to shift location during turning?” --I have to say that subjectively, at times I’ve felt that cornering at high speed (as in a fairly sharp highway curve) stops the shaking. I don’t have 100% confidence in saying that though

One other thing I can say - the car really started shaking on a trip from NYC to Boston after the July 4th weekend. Brought it in to a tire shop, since I had tires replaced just prior, and they told me that it was balancing. They did a balance job, and the shaking stopped for months. Now, it’s back. Don’t know if that info is useful at all

Sounds like a very useful clue to me. Perhaps you have thrown a balancing weight or two. Try getting the wheels balanced again.

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Or the tires could be out of round. But agreed on having the balancing checked too.

Good point. Those weights do tend to come off. As evidence, I have two coffee cans completely full of those weights I’ve found along-side the road, found during my daily walks over the past few years. Sort of a questionable design to place the weights at the edge of the rim, given they seem to fall off in considerable numbers. Add to that, over time weights placed in that location can cause air leaks. Do tire shops continue to install weights on the rim, or have they moved them to somewhere else now? Occasionally I’ll find a wheel weight along side the road that appears like it has been glued on somewhere, doesn’t have the rim attachment gadget.

Tape on wheel weights. 99% of the vehicles I work on have no lip to accept a clip-on weight, these are all alloy wheels.
Example below of a Volvo wheel.

image

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