After man questions about steering wheel shaking causing people to replace everything from engine mounts to the kitchen sink, I’m tossing out my personal rules of thumb on the matter based on my experience. The following can certainly apply to any car, but in particular, my experience is in FWD cars. I boil it down pretty simply. Vibration while accelerating is commonly an axle issue, usually the inner joints. A vibration while cruising or costing is often a wheel or balance issue. A vibration while braking is an issue with rotors, most commonly pad deposits.
Shaking accompanied by clunking or clanking or other noises should definitely be checked out immediately and closely!
Shaking steering when…you accelerate:
You have an axle problem, usually caused by worn inner joints or possibly an axle balance issue. In highly worn axles a slow “walking” of the wheel back and forth while going straight at speeds under 10-15 mph can be noticed, but this may be dampened by power steering systems. Another sign an axle joint might be bad would be noises like knocking or rattling when turning in tight circles at slow/med speeds, indicating outer joint wear. Since your typical transaxle half shaft is not long enough to really exhibit a balance issue we recommend replacing the axles with new or rebuilt units OR IN THE CASE OF THE TSX, the inner joint only as this has been found to be the most reliable fix.
Shaking steering when…you coast:
You have a wheel balance issue, which can only really be truly diagnosed at 60 mph or higher. It can be noticed at slower speeds, but it usually won’t appear or be obvious until 60. However if it does not appear at 60-65 mph, there is a good chance the car does not have a balance issue.
First, make sure the tire pressures are accurate. Stick-on weights can fly off the wheel causing this issue so make sure there is no evidence of missing weights.
As tires wear (even or uneven) they can throw off the wheel balance as well, so make sure the tires are not excessively worn. Sometimes well-wearing tires may need a rebalancing before they actually need replacing.
We have also seen balance issues occur at minimal speeds in situations of juvenile joyrides. Off-roading after rain will cake wheels with mud causing severe balance issues.
Less common but also possible issues of coast-shaking include wheel damage like denting or gouging and tire damage such as tread delamination and sidewall bubbles. To test for a bad tire that might be causing a steering wheel shake, rotate the front tires to the rear to see if the vibration moves from the steering wheel and into the chassis.
Alternative to the vibration while the coasting issue would be a bad shock absorber, which would be accompanied by extremely poor handling and potentially odd “skipping” tire wear.
Shaking steering when…you are braking:
You have an issue with your brake rotors, most likely pad deposit build-up from sub-par brake pads. For the most part, these vibrations must be experienced under braking from speeds over the 60 mph marker. Vibrations at lower speeds than this are usually rotor warping issues but are also very rare. In these cases, one can feel the brakes sequentially grab and release with consistent, light pedal pressure at low speed. The fix here is to machine or replace the rotors.
More commonly, pad deposits formed unevenly on the rotor surface can cause vibrations usually at higher speeds, and heavy braking maneuvers or re-bedding can sometimes remedy the problem, and if it does this can be an indicator that the driver should try using different brake pads more suited to their driving style. Vibrations in the steering wheel indicate a front brake problem. A feeling of vibration in the car’s body or the seat of your pants usually indicates a rear problem. Pulsation in the pedal can be inconclusive as to front or rear issues while either or both of the issues can exist. To test a rear brake shimmy apply gentle pressure to the e-brake while coasting without touching the pedal. A rear-wheel vibration will be apparent then, depending on the car’s design.
Heeltoe does not cite alignment issues as cause for steering wheel vibration. Alignment problems cause pulling, poor handling, and uneven tire wear which can affect wheel balance, but a bad alignment itself will not manifest in shaking.
Also, wheel bearings will not cause vibrations until they are extremely worn, and at this point, the noise inside the car will be blatantly obvious. A wheel bearing can be heard long before it is felt (at least with regard to the Honda and Acura vehicles we have experience with dating back to 1980 and older).
Aside from these rules of thumb, one should consider that other problems can exist. Aftermarket wheels which are not hub-centric and do not have hub rings installed can cause vibrations in some cases. Also, loose suspension bolts can be problematic as well.