Mazda3 - Slight vibrations, noises and rocking

Question

I just bought a 2006 Mazda3 with a manual tranny (first time stick driver) and it so far has been a great car barring any newbie manual mistakes. I've noticed a couple things that I am curious of whether they are normal for the car or need to be checked out.

1. I have noticed slight shaking/rocking when letting off and pressing down the gas. I would describe it as a forward and backward, almost bouncy motion that rocks about 2-3 times quickly, rather than a shuddering of the entire car. Even if I feather the gas it still seems to do it about half the time, and the effect is less noticeable in higher gears.

2. At speeds around 50mph+, 2.8k+ RPM, and when in 5th gear the entire car sometimes shakes and can be felt in the steering wheel. I only notice it in a particular section on my drive to work which is slightly uphill so I could see there being too much load for that gear, though I haven't driven on the highway at cruise enough to see a pattern.

3. There seems to be a low vibration/humming throughout the entire car at idle and when driving. I can feel it in my steering wheel and in the dashboard. It's not strong so no loss of control but I definitely "feel the car" more than I did in my previous one. At idle the engine has a loud hum. The RPMs do not fluctuate at idle.

Thanks in advance for your help. I am a bit of a car noob so I don't have the materials to fix anything myself though if there's anything I can do to test/diagnosis these issues I'm all ears.

Answer 1

Welcome to the site. What you have described are typical nuances of any 10+ year old car that may need some work.

Vibrations and shaking can be caused by worn engine/transmission mounts, worn or out of balance tires, worn shocks/struts, worn wheel bearings, need for a tune up, bad gas, etc.

This answer is very general in suggesting what to check. You may find nothing more than the car is different than your previous one.

1) May not be anything. Check excessive movement in the engine & trans mounts.

2) This sounds like tire balancing. Have the tires inspected and balanced. That RPM at that speed should be OK on an incline. If the problem persists, it could be related to #1.

3) Feeling a vibration or "hum" may mean nothing other than this car is different than you are used to. Address the other issues first, then if this one is worse or unbearable, try to find the source. If it only happens when the car is rolling, and increases with vehicle speed, it could be wheel bearings. If it happens when the car is stopped, it could be related to #1.