Drive Train Vibration

[bmorgan9119]

When driving my 2009 CX-9 Sport - I often experience the sensation of driving over rumble strips when driving at low speeds (28 - 32mph). This usually happens within the first few miles of a trip - it doesn't seem to happen after I have driven for 10 miles or so. Any thoughts?

Could this be related to TSB 0300608 ?

[sts7049]

first thing i would check is tires. Any knots, etc? Then maybe check trans and diff fluids..

[ceric]

At 30mph, our tire (29.8" diameter) rotates about 5.8 revs/sec.
That definitely feels like driving on rumble strips.
It is likely the tires if it goes away.
Could be flat spotting. What tires do you have? OE?

[bmorgan9119]

I thought that new tires and an alignment etc would make it go away but it didnt. Different tires (not OEM) - same issue, so it's not the tires. Tire pressure is at spec btw

[Antonio DiMarco]

There have been instances of the awd system failing, my dealer has replaced a few of them, supposedly it's a Ford part that was manufactured out of spec. You may want to get that checked. The vibration maybe an early warning. Also these cars are extremely sensitive to out of balance tires. My 6 had to get a road force balance on each tire to get them rolling right. Many dealers won't do roadforce, due to added time, or can't.

[ceric]

In my opinion, suspension/drive shaft issue (including bearing) is unlikely to go away after warm-up, which you mentioned.
What goes away after warm-up usually has some sort of fluid/grease involved (better lubrication after heated up), or tires (flat spotting).
Brake is another one, which is not related here.

Hard to guess from afar. You need to give more clues.

P.S. OE tires have no flat spotting issue (that is why I asked). Some tires might have. The wider the tires, the more likely.

[helbigtw]

Many dealers won't do roadforce, due to added time, or can't.

Or, my local tire shop just down the street, part of a chain, (S&S Tire), which is not listed on The Hunter RFB's website, tells me that they have "one of those."
I peek my head into their shop, and all they have is a standard balancer.

Its pretty ignorant when a tire shop does not even know what kind of equipment they have, or what the difference is.

Needless to say, this shop down the road, I only take my company vehicle there, would never take my personal vehicle.

[55V8]

@OP: How often do you drive your Cx-9? If rarely (say once a week, every other few days or more), I would say the tires are just flat-spotting.

[ceric]

I used to have 255 rear tires on my BMW 540iA. It flat-spotted over night (about 12 hrs).
After a few miles of driving, it went away. The wider the tires, the more likely.
It is also tire-dependent (of the construction of the tires).

[sts7049]

does the rumbling change frequency or anything across gear shifts? meaning, if the engine RPM drops or speed drops does the rumbling change in any way?

[ceric]

Agree with sts. If it is gear related, then it could be the transmission or drive train.