If the shake comes on when you press the gas and fades when you lift off, it's usually an inner CV joint or a broken engine mount. If it shakes at a certain speed whether you're on the gas or coasting, it's a tire or wheel, and balancing is $37 to $55 (RepairPal).
None of these will strand you tonight. All of them get worse, and a CV joint that finally lets go can leave you with no drive at all. Get it looked at within a couple of weeks.
The one test that sorts most cases
Drive at the speed where it shakes, then take your foot off the gas and coast. If the shake stops, the problem is in the driveline or engine: CV joints, mounts, driveshaft, or a misfire. If the shake continues at the same speed on and off the throttle, the problem spins with the wheel: tire balance, a bent wheel, a bearing, or a dragging brake.
That one observation changes which shop you go to and saves a diagnostic fee. Tire shops fix the second group. Mechanics fix the first.
Most likely causes, in order
For a shake that's only under load, inner CV joints and engine mounts lead, in that order on front-wheel-drive cars. For a speed-related shake, tire balance leads by a mile.
Cause | How it feels | Shop cost (RepairPal) |
|---|---|---|
Worn inner CV joint | Shudder on acceleration, worse under load and uphill, gone when coasting | $1,010–$1,132 for a CV axle shaft |
Broken or collapsed engine mount | Clunk when you shift to drive, shake on takeoff, engine visibly rocks | $643–$798 per mount |
Unbalanced tire | Steady shake in one highway speed band, on or off the gas | $37–$55 to balance |
Bent wheel or bulged tire | Like imbalance but balancing doesn't fix it | New tire or wheel |
Loose lug nuts | Wobble that started after a tire change | Free to tighten |
Worn wheel bearing | Hum or growl that changes when you steer, plus vibration | $346–$504 |
Bent driveshaft or worn U-joint (rear-drive, 4x4) | Vibration from the middle or back of the car under power | Varies |
Dragging brake caliper | Shake plus pulling and a hot wheel | $898–$968 per caliper |
Engine misfire | Shudder that's worst under load, check engine light, rough idle | $238–$399 for a coil or plugs |
RepairPal's figures are national parts-and-labor averages and don't include tax. They also vary a lot by car. A CV joint alone is $320 to $434 on a Chevy Trailblazer and $1,923 to $2,020 on a Honda Accord on the same site, which is why most shops replace the whole axle shaft instead of the joint.
The inner CV joint is the one people miss. The outer joint clicks on turns and everyone knows that symptom. The inner joint doesn't click. It develops play in its tripod bearing, and under torque that play turns into a side-to-side shudder you feel through the whole car. The Drive points out the only thing protecting either joint is a rubber boot, so a torn boot and a ring of grease flung on the inside of the wheel is the tell.
Engine mounts fail quietly. The rubber cracks or the fluid-filled kind leaks, and the engine starts to rock on takeoff. The SHO forum thread on this exact symptom is a good example: a shudder under acceleration and engine braking, smooth at steady speed, with a broken front mount as the lead suspect. The owner replaced brakes first and the shake stayed, which is a brake job's worth of lesson in testing before buying parts.
Tire balance is the cheap one, and The Drive's advice to "count yourself lucky" if that's it is right. A wheel weight falls off, or a new tire wasn't balanced well, and you get a shake in a narrow speed band. The giveaway is that it doesn't care whether you're accelerating.
Can you keep driving, and for how long
A tire-balance shake: yes, for as long as you can stand it, though it wears the tire and suspension faster. Fix it this month.
An engine mount: yes, for a few weeks. The risk is secondary. A rocking engine strains hoses, wiring, the exhaust and the other mounts, so one dead mount tends to kill its neighbors. RepairPal also warns that cheap aftermarket mounts can bring vibration of their own, so pay for a decent part.
A CV joint: a couple of weeks of gentle driving if it's just a shudder. If it's also clicking, clunking, or the boot is torn and slinging grease, sooner. A joint that fails completely on a front-wheel-drive car means that wheel stops being driven, and the broken shaft can damage the transmission case or the brake line on its way out.
Loose lug nuts: stop now and tighten them. A wheel that started wobbling right after a tire rotation needs checking today, not next week.
A misfire shake with a flashing check engine light: stop and tow. That's a catalytic converter problem in progress, not a vibration problem.
What it costs
Cheapest to dearest: tighten lug nuts (free), balance tires ($37 to $55), a coil or plugs ($238 to $399), a wheel bearing ($346 to $504), an engine mount ($643 to $798), a CV axle ($1,010 to $1,132), a caliper ($898 to $968). All RepairPal.
Budget for more than one mount. Shops often recommend replacing the pair, because the surviving one has been carrying extra load. And on a CV axle, ask whether they're fitting a remanufactured or new aftermarket part and what the warranty is. Cheap axles with out-of-spec joints are a known cause of a shake that comes back.
What to do today
- Do the coast test. Note the speed the shake starts, then lift off the gas. Shake gone means driveline or engine; shake stays means tire or wheel.
- Walk around the car. Look for grease on the inside of a front wheel (torn CV boot), a bulge on a tire sidewall, or a missing wheel weight.
- Open the hood with someone holding the brake, and have them shift between drive and reverse at idle. If the engine lurches an inch or more, a mount is gone.
- Check lug nut torque if the wheels came off recently. Any tire shop will do it in two minutes.
- Book the right shop. Tire shop for a speed-related shake, mechanic for a load-related one, and tell them the result of the coast test.
Sources
- RepairPal: Axle Shaft Replacement Cost
- RepairPal: CV Joint Replacement Cost
- RepairPal: Engine Mount Replacement Cost
- RepairPal: Tire Balancing Cost
- RepairPal: Wheel Bearing Replacement Cost
- RepairPal: Brake Caliper Replacement Cost
- RepairPal: Ignition Coil Replacement Cost
- RepairPal: Spark Plug Replacement Cost
- The Drive: Here's Why Your Car Vibrates When Accelerating
- Rerev: Car Shakes When Accelerating but Not When Coasting
- SHO Forum: Bad Shuddering on Acceleration, CV Joints or Motor Mounts
Featured image: CV Joint with broken tone ring by Kiwiev (CC0). Source
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