Noise/vibration diagnostic help?

It's my daughter's 07 Honda Fit Sport automatic, ~180kmi, General Altimax Arctic tires with ~3k on them. 

She's been complaining of an intermittent noise & slight vibration. I got to experience it briefly a couple weeks ago from the passenger's seat - we were doing about 60mph down the highway when heard & felt what sounded like a tire getting ready to fail on the RF corner. It started gradually, got a bit louder, then stopped. All within a mile.

It seems to be happening more frequently though, and today I had her take it to a shop I trust(the same ones who installed the tires) to check out. The ball joints, tie rod ends, wheel bearings & CV shafts all seem good. There's no sign of damage or defects to the tires either. She's not hit any potholes or anything that could have damaged a tire either. 

Any idea what we might be overlooking?

I think a tire issue wouldn’t be (generally) intermittent.

How about alignment? Specifically caster? I created my own caster problem when lifting my first XJ Cherokee and it came on like that and went away like that too. What can cause a caster issue with those?

Have the tires been rebalanced recently?

Alignment & pressure checked? (D'oh, E&I beat me to it)

In reply to ebonyandivory :

We've not had it aligned in the year she's owned it, but it drives nice and straight. 

In reply to EastCoastMojo :

The tires only have ~3000 miles on them, so not yet. 

Sounds harmonic.  Maybe swap front tires to the back.   Check the wheels for trueness.

Sometime the belts on the tires go wonky.   A long shot may be the rotors.

In reply to Dirtydog :

I think it's too sporadic to be harmonic - at least what I felt/heard? It only happened once, for a mile, in 15-miles. 

Rotating tires is a good idea though & I'll have her do that at the next oil change. 

In reply to Pete Gossett :

If it’s speed (not rpm) related, make sure the caster is within spec.

Seems like it's something intermittent, you state that it stopped at some point out of the blue during a drive?  If this were a tire/wheel issue it would be present all the time at speed.  If the front end checked out per the mechanic, then I'd look at the brakes as a possibility.   A sticky caliper can cause a vibration and come and go.  I had this happen to me once with a BMW, I took the car out onto the highway and  and all of a sudden the front end felt like it was going to shake itself apart.  I pulled over and got out and checked the front end, then just placed my hand carefully on the front wheels (never touch a rotor unless a car is cooled off) and sure enough one of them was much hotter.  I let it cool off a bit, then drove home and replaced the caliper, all good from there.  

I'm a big fan of the idea of the sirometer, it's just that I've never had the opportunity use mine yet.

https://www.amazon.com/Briggs-Stratton-19200-Tachometer/dp/B0044AV5VK

Get the vibration to happen, place the sirometer on something solid and vibrating (ie the dashboard). Pull the wire out and read the rpm that it vibrates the most. Note vehicle speed and engine speed.

Do a little math to figure if the rpms of different spinney bits. Like the wheels and axles, crankshaft, cams, or accessories.

Then the RPM reading should match up with something you've calculated or possibly a multiple of the frequency.

I recall several Honda customers with similar concerns. Possible defective RF wheel speed sensor or harness connecting sensor to ABS harness.  Pull the wheel and inspect. Although you are not in the Rust Belt, check for rust jacking at the mounting point of the sensor or build up of iron particles on sensor.

Does it happen in a straight line? My 03 BMW 325i would get a severe vibration/wobble only during slight left turn-ins on the highway and it turned out to be one of the control arm bushings on the front right. 

In reply to outasite :

Actually she is in the rust belt, though the car was from FL. However the PO had it stolen once, but it was recovered with minimal damage(and a missing radio). It's possible there could be an issue with the speed sensor, but not be visually obvious. 

In reply to westsidetalon :

Yes, straight line only. 

In reply to RossD :

That's a(nother) tool I'd love to own! In this case just getting the problem to occur is causing the most difficulty in diagnosing it. 

Sticky caliper sounds plausible.   How about a wheel brng ?

    caster causing vibration .   As to how.

In reply to Pete Gossett :

The diagnosis was difficult with these Hondas because of sporadic events. The first car was repaired by replacing the sensor even though it tested good. After that, other cars with similar issues were road tested, inspected and the sensor was tested for output. If nothing proved bad, replacing the speed sensor solved the issue.

I have seen  ABS issues due to the previously mentioned rust jacking and the sensor covered in iron particles on other vehicle brands. A quick visual inspection without disassembly will not always catch these problems.

In reply to outasite :

Thanks! She's heading down here in May after graduation. Hopefully it'll hold up until I can get eyes on it. 

This happened to an old scion I had. Finally tracked it down via witness marks. At some random speeds and wind loads, the fender liner would rub the outside edge of the tire tread. Worth a look.