A shaking car when the brakes are applied is the last thing anyone wants on the interstate. Vibrations like this are almost always indicators of a small issue on its way to becoming a large problem.
So, can your brakes cause your car to shake? Yes they can, and you’ll need to have them inspected immediately. Noticeable vibrations could be an indication of imperfections in the rotors or drums, depending on your specific car model.
A vibrating car when brakes are applied is a serious issue that you don’t want to ignore, and ignorance on this topic is unlikely to be forgiving in the long run.
Possible causes
Remember, it is best to have your brakes inspected by a trained and experienced professional.
This isn’t something that should be solved with guesswork in your driveway on the weekend. With that being said, there are more than one pieces of the typical braking system that might fail – which means you have multiple points of possible failure on your car that may need to be checked.
On most modern cars, disc brakes are used in the front wheels. Disc brakes have a rotor (or disc) that rotates with your wheel, and is stopped by two brake pads that squeeze the disc to slow down your car.
Ideally, they should have a uniform thickness and should be flat on both sides without any waves or wobbles. Any variations in the material will prevent your brake pads from having constant contact with the rotors when you press your brake pedal.
The other most common type of brakes, drum brakes, may still be used on the backs of some less expensive modern cars, but are more likely to be found with older models. Drum brakes have two braking pads that press on the inside of a drum or cylinder that rotates with your wheel.
Vibrations from this configuration may be caused by problems similar to those found in the rotors: material thickness and surface uniformity. The brake pads inside the drum need to be able to contact the drum surface without interruptions from waves, wobbles, cracks, or other imperfections.
How Do Imperfections Happen?
These imperfections in disc or drum brakes can sometimes be caused by over worn rotors or drums. Brakes are a fairly simple concept – spinning wheels are slowed down with friction. Friction always generates heat, which is the reason sliding down a rope too quickly or too long can make your hands burn.
You solve your burning hand problem by removing your hands and waving them, possibly while saying a few choice words. Waving your hands dissipates the heat and cools down your skin.
Minus the profanity, brakes are pretty similar to us. The friction from slowing down your car generates heat, and that heat needs to be dissipated.
If the rotors or drums are worn down, which naturally happens over the course of their life, they may not be able to remove heat effectively. This can lead to warping of the material and uneven surfaces.
Vehicle vibrations love company, and these uneven surfaces will only lead to more issues, unfortunately. Like most problems, this is not going to solve itself.
But what if age and over-use aren’t the cause?
It is very possible that the lug nuts (the nuts used to fasten your wheels onto your vehicle) have been over tightened, or tightened without the needed uniformity.
These nuts need to be tightened with a torque wrench – a tool that lets the user choose the amount of force used. Other tools with less control (like an air-powered impact wrench) may end up over tightening the lug nuts, which can lead to warping of the rotor over time.
The torque needed for your specific car model can often be found in your owner’s manual or online.
Solutions
In any case, whether warping is caused by age, heat, corrosion, or excess tightening, your brakes need to be inspected by a mechanic – visually and with tools to measure any variations.
If the issue isn’t too serious, the rotors or drums may be able to be reused after some machining. More serious defects may mean that the rotors or drums need to be replaced.
On that note, remember that brake pads need to be replaced as they wear out. The recommended replacement frequency varies from 30,000 to 50,000 miles, give or take, but this can (again, see a pattern here?) be found online or in the owner’s manual for your vehicle.
If you have disc brakes and visually inspect your brake pads (and you should), remember that there should be at least 1/4 thickness of the braking material left, or more. Any less is evidence that you need to have your brake pads changed.
Even in the absence of any issues, don’t neglect to have your brakes checked at least once a year and whenever you have other work being done. The risk of neglect isn’t worth the cost.
Other Possible Causes of Vibration
- Poor Alignment can potentially cause vibrations and additional wear on your tires. Worn tires can also create shaking, if they wear unevenly. An inspection will help to determine your need for either a two wheel or four wheel alignment.
- Ball joints and tie rods can create alignment issues when then fail, leading to the issues noted above. These are part of your suspension system. If you only experience vibration while turning, you may want to have these and other parts of your suspension inspected.
- Wheel bearings are used to create smooth motion in most rotating objects, and that includes your wheels. A bearing that’s beginning to fail will often create noise and vibrations.A bearing that does fail can be a borderline horrifying experience if it happens while driving.
(Yes, it happened to me. No, I never want it to happen again.)
- Wheels, though we already mentioned these, remember that tires need to be balanced and rotated to avoid shaking and uneven wear. Consult your owner’s manual for the recommended inspection and service frequency for your vehicle model.
- Engine spark plugs can shake the engine if they wear out and begin to misfire. This can be fixed with a replacement, if the spark plug is the issue.
- Timing belts wear out eventually, and this can create misfiring in your engine, which in turn leads to vibrations. Remember that engine misfiring can potentially lead to much worse (and more expensive) issues if it is left unresolved.
This list is a good place to start, but is not exhaustive by any means. A vibrating car is never a good sign. Any noticeable issues need to be inspected and fixed immediately – before they destroy your suspension or cause an accident.
Vibrations rarely solve themselves, and will only lead to more (and worse) issues down the road. The cost of neglect is almost always higher than the cost of repair.