Let's play: Name that vibration!

Rio getting final preps for One Lap. Vibration that has been there for a bit is getting worse. 

Conditions it happens:

40-48mph (this morning stretched to 52 and more intense), coasting, under power, in gear, out of gear, braking.

What's been replaced in he last 16 months:

Axles (twice), control arms, lower engine mount, inner/outer tie rods, bearing/hub/knuckle both sides, rotors and pads. This has done it with 5 different wheels/tires and always in that same range. Happened later last summer, changed back to stock suspension still there, switched back to coilovers still there. 

Ordered a pair of rear hubs (SKF) mostly because they are OE with 118k miles so while I don't think this will fix it, it should be done anyway.

So slip on those internet diagnosis caps and GO!

photo for attention

Vibration in steering wheel?  Vibration in pedals?  Vibration in interior that isn't felt with the steering wheel?

Sounds like it's NOT engine related, but speed related.

When you said you had 5 different wheels and tires on it, do you mean sets of tires and wheels?  If not, 2 bent wheels could account for it.  

Oh, out of the blue thought...

I have had undertrays, mudflaps, rear bumper covers, etc flap like crazy at certain speeds that caused vibrations.  Check the plastic on the car.  Also, have somebody drive beside / around you and look for panels / pieces flapping around while in that speed range.

It's a rotational vibration. You feel it through the body and steering wheel. 

I've had 2 different sets of OE 17x6, 205/45/17 wheels tires(one set Falken all season, one set Ironman AS), one set of sparco 15x6.5 wih 195/60/15 Goodyear all seasons, one full set of 15x7.5 with 205/50 615's (along with 2 spares) and now the new 16x7.5 wih new 215/45 615's. 22 different wheel/tires have been on this car while it does the same thing. 

following up on the above questions: is there any sound associated with the vibration?

speed-related vs rpm-related, and independent of throttle, says it's something downstream/outboard of transaxle or perhaps not powertrain at all (ie could be aero-related).

no sound other than the  sound of 615's through hollow body panels on rough road surface.

steering rack bushings worn out and there's some kind of harmonic thing happening?

is the vibration present when turning?

There is a really cool app you can get if you have a smartphone with a G sensor (pretty sure any iPhone in the past ten years does) where you put the phone on the floor, do the vibration, and it analyzes the first/second/third order so you know if it is wheel speed or engine speed based or "other".

I mean, you covered all of the easy things, although new means Never Ever Worked so you may have got a run of bad hubs or something.  I'd get a dial indicator and check that the wheel studs are not offset (ignore the center bore).

Although that speed makes me think more drivetrain than wheel balance/out of round issues.

In reply to Pete. (l33t FS) :

Drivetrain is what I had thought as well. Which is why we are on our second set of axles. 
 

anything out of round "should" make the vibration at all speeds one would think. There are times you can "power " through that speed range and skip it. Get from 35-50 fast enough and you don't notice it. 

In reply to AngryCorvair (Forum Supporter) :

Yes turning it is still there. 

Put it [very safely] up on supports with the wheels off the ground and run it, with someone watching/looking for anything suspicious. 
 

Variations to try if it vibrates on stands:  without the wheels, without the rotors  

if it doesn't vibrate, it could be in the rear

any bearings on the cv axles?

Is there any opportunity in the motor mount replacement or related operations to introduce any preload into a mount bushing, on the drivetrain or exhaust?

The two related thoughts are that the motor mounts on my Mini were slotted and didn't force a "correct" orientation between engine and body, and that I had an engine-swapped E30 that had deeply terrible vibrations at some speeds until I remade the trans crossmember so that it wasn't squashing or stretching the bushings on installation.

The "powering through" aspect suggests the possibility that something sympathetic needs to get going, so passing through the needed frequency quickly avoids it. Or perhaps that the torque load from the powering through loads or unloads a bushing enough to obviate the issue or move the frequency.

bobzilla said:

In reply to Pete. (l33t FS) :

Drivetrain is what I had thought as well. Which is why we are on our second set of axles. 
 

anything out of round "should" make the vibration at all speeds one would think. There are times you can "power " through that speed range and skip it. Get from 35-50 fast enough and you don't notice it. 

Axles are USUALLY only under load.  Some vehicles (honda) do not tolerate aftermarket axles and will shudder horribly, too...

...under load only.

In reply to Jesse Ransom :

Not related to the lower mount replacement. That was done well over a year ago and it did not start happening until last fall. There's 3 mounts, one over the trans hanging it, one on the passenger side hangng the engne and a torque mount back by the diff to keep it all from rotating. nothing to preload or stress. 

In reply to Pete. (l33t FS) :

I had a tempo that would start vibrating he passenger axle (long axle) when it started to go bad similar to this but that was 30 years ago. I had hoped it might be as simple as a E36 M3 axle. 

Wild guess here, but are the low frequency noise dampeners installed on the rear calipers?

Not sure if they were missing if they would cause what your seeing, but an easy check to see if they are there in case there is some harmonic happening at those speeds. 

In reply to No Time :

Never even heard of this. Changed pads many times on this car, even changed calipers back there once. Did it before and after. Considering there is no noise not sure this would apply  

EDIT: just googled that and no, these cars dont come with that. This, the other rio, the forte, the other forte, the other other forte, the EGT nor the Tiburon. Not a Korean car thing at least on the lower end (below say a$50k genesis)

In reply to bobzilla :

Oh well.

Like I said, wild guess. Now updated to incorrect wild guess 

I had pulled up 2013 Rio on the RA site and they showed up under brake parts. 

In reply to No Time :

Hey it's worth a shot. I'm about >< close to paying our tech for the bs to find the damn vibration. 

Nothing useful on iATN, under Kia or Hyundai.

Name that vibration? My wife and I can barely talk about this game, much less post about it on the internet!!!

All joke aside, maybe a brake rotor is not in balance? Does the rear have drums? Could there be something wrong with those?

Maybe there is some crap on the hub beneath the rotor causing the rotor to not seat flat on hub and therefore the wheel doesn't sit flat to the hub either?

In reply to Robbie (Forum Supporter) :

4 wheel disc, had this vibration with 3 sets of rotors. Always wire brush the hubs when I change and relube with antisieze. 

Do you remember when you first noticed it? Maybe too obvious but what had you just done?

Also, maybe the stock axles have those rubber vibration dampers on them but replacement axles do not?

In reply to Robbie (Forum Supporter) :

first replacement axles did not, did not start vibrating until last fall. second replacement does, vibration did not change.