Q: Car shakes when I slow down.

asked by on

On the interstate I had to put the gas to the floor to speed up and get past someone then after that the vehicle shook and vibrated when I slowed down.

My car has 164000 miles.
My car has an automatic transmission.

Hello. The imbalance of rotating parts on a car, such as your wheel and tire assemblies, is a function of speed but also "positioning". When you were traveling at a steady state rate, say 65 MPH, the suspension was clearly capable of withstanding whatever residual imbalance exists in the rotating assemblies and thus the residual imbalance is essentially invisible to you (not felt).

Nothing that rotates on a car is ever perfectly balanced. Rather, the components are balanced just to the point where the residual imbalance creates ONLY vibration that is below the threshold of detection. The imbalance is there; it’s so small though your car suspension doesn’t transmit it through (the steering) wheel or vehicle frame. What is happening in your case when you suddenly accelerate and then completely unload the drive train (by taking your foot off the gas and coating) is you are changing the position of the rotating elements (wheels and tires) such that the imbalance that does exist is "magnified" and thence transmitted through the vehicle. The practical causes of this are worn tires and worn suspension parts that are not holding the wheel/tire assemblies in the same fixed position during coasting as during acceleration. That is the likely cause.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Car shakes when I slow down.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My car is difficult to accelerate after running for sometime

I believe there is a fuel filter on your vehicle as well. Was that changed too? A new fuel pump cannot perform with a clogged or partially clogged fuel filter. For issues like this, a technician will be able to...

Q: Direly need advise on what to do here.

The problem you have with the cars engine and transmission will far exceed the costs to repair it and will not be worth the money to do any of the repairs. If you want to fix the head gasket leak...

Q: My fans stay on when I turn my car on and my temperature gauge stays on cool and will not move up even when the car is running

Hey there. This can be caused by a number of things such as low coolant levels, a faulty thermostat, or a failing coolant fan switch. As you may know, the coolant fan switch helps to maintain the proper coolant...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...