The NVH gear steered my away from the "WB" and basically sent me into a spin! I don't have the knowledge or experience with NVH diag to proceed, need some idea's on the next step.
my initial captured was with a accelerometer on driver seat rail inner (see attached pic and first file ie; not subframe). I then moved to 2x accelerometer both at the rear sub-frame mounting bolts each side. Hoping to narrow it down to which side of the car it was coming from..the results in my mind were inconclusive!?
I also tried 2x mic's in each foot well with nothing conclusive revealed(again in my mind).
how do you associate a frequency with a component when it isn't of one of the fundamental orders?
any idea's would be greatly appreciated!
Steve Smith is the man on NVH and I am sure he will pick this up as soon as he can. In the meantime can you confirm the exact vehicle details (the file says Kia Sportage but that is a bit vague!). Is it 2Wd or 4WD if 4WD does selecting 4WD change the complaint?
You say that your ears tell you that it is Left Front but you state that you "placed the accelerometers on the rear subframe". Did you mean that?
What mechanical checks have you carried out wheels, tyres, suspension, driveshafts etc. (Runout, deformity, lift, play etc.)
Have a look at this case study https://www.picoauto.com/library/case-s ... celeration as an example of the fun and games that HNV can draw you into.
Thanks for your reply, 2012 AWD diesel 2.0l vin KNAPC. Auto Trans with Gear ratio as per advanced settings page, can't find a rear differential ratio but I assume same as front.
Per checks zero physical measurements, I was hoping for direction from NVH equipment!
I did replace all oils(Trans/front diff combined; transfer box, rear diff)as it was almost due, with special care taken to capture any particals that any compartment might of been making. Nothing abnormal found. IE: only the normal amount of metal on the magnets and I filtered the oils through a rag and didn't see anything alarming.
Tyre pressures are good, AWD is selected automatically via PWM controlled constant torque coupling at the rear differential. There are no dtc present.
I'll read the topic you suggested.
Still unsure about exactly wher you placed the accelerometers.
On the bolts that secures the subframe to the chassis(each side see attached pic) which I would says sits about in line with each inner seat runner rail and approximately 15 cm in front on on each front seat. I should of said Rear mounting bolts of front subframe.
It is a heavy mass and I don't believe it would be prone to resonance for want of a better description.
Also notice that the disturbance in the .jpeg (1st post)was on the z axis. I've been racking my brain trying to think of things that would be prone to movement on the z axis at that those frequency?
Before we move on, I would like to eliminate any measurement error and clarify the captured data
Looking at the file “KiaSportageNoise17.1.2022”, could you confirm this is a 3-axis accelerometer mounted securely on the driver’s seat rail in the correct orientation (See image below)
The reason I ask is because of the high lateral amplitude you have captured (Green Channel C, Z Axis) and highlighted in your first image
This is present at varying amplitudes throughout your capture (not just during deceleration) and related to vehicle speed or vehicle motion.
To qualify could we repeat this test whist free revving the engine with the vehicle is stationary; noting the lateral vibration levels between 60 and 120 Hz?
I would hope they are low and only present once the vehicle is moving.
The peak of this lateral vibration level at the driver’s seat was during deceleration @ 18 mph (See below)
Note above how the peak lateral vibration is a 32nd order of T1. This is purely for “notes” at this stage (i.e., 32 disturbances for every one revelation of the wheel)
My line of thinking here is tyre tread pattern, tyre “out of round” and tyre contact “patch” with the road surface. Tyres tends to create a droaning noise under deceleration as they are loaded by the retardation of the vehicle mass. (They also “droan” down to very low road speeds too; almost 0 mph)
I know this may have been mentioned before but can we check for “out of round” of each tyre, their wear characteristics (any clues in the tread pattern) and their circumference.
Varying tyre circumferences will play havoc with 4WD and AWD drivetrains
Would the vehicle have “chunky” winter tyres installed? If so, are there 32 blocks of tread about the circumference of the tyre (i.e., perhaps 4 rows of 32 tread blocks per row)
Coming back to the vehicle history, has any work been carried out recently?
When was the noise first noticed?
Is the noise related to temperature of the vehicle and its components?
Is the noise related to the road surface/texture?
Can you feel lateral movement of the vehicle at low road speeds?
Moving onto “KiaSportageNoise17.1.2022_h_subFrame” and the image provided, thank you for the clarification on mounting location
Nice work on choosing a “heavy mass” location point too
Looking at your set up for this file, we have used 2 x accelerometers
One is measuring 3 axes at the Front subframe RH rear mounting bolt (Channels A, B and C)
Can you confirm the orientation of the accelerometer for this configuration? Was it vertically mounted with the screw thread facing forward, like the first image in this reply?
The other is measuring a single axis at the Front subframe LH rear mounting bolt but (Channel D) Which axis was chosen to measure the vibration?
Sorry to repeat this question again, can you confirm the orientation of the accelerometer for this configuration? Was it vertically mounted with the screw thread facing forward, like the first image in this reply?
I ask these questions to help clarify the test results; below we have the vehicle decelerating at 17 mph but with a much lower amplitude of vibration in our area of interest (60 … 120 Hz)
If our accelerometers are mounted vertically with the screw thread facing forward, then channel C is measuring the lateral vibration of the vehicle at the Front subframe RH rear mounting bolt whereby the vibration is lower than in the cabin
If channel D is capturing the lateral vibration at the Front subframe LH rear mounting bolt, then the same applies
What I have noticed, which is very interesting indeed, is the multiple harmonics you have captured below
These are characteristic of bearing wear and both channels A and D have captured such events during acceleration, not deceleration. Could you feel/hear the noise/vibration at this point in your capture?
We must be mindful of chasing peaks that are not related to the customer complaint, hence the question above. (Again, this data is for "notes" only at this stage)
You mentioned microphone recordings too, would you have this file, if so, could you post for review?
To recap on the above, I would tackle this vehicle as follows:
• Find a favorable road surface to demonstrate the noise/vibration at its peak
• Note if a change in the texture of the road surface changes the noise level
• Find the optimal engine and road speed condition to demonstrate the noise/vibration at its peak
• Try as hard as possible to maintain steady engine/road speed and load conditions such as to prolong the peak vibration/noise levels. (This makes analysis of captured data much easier)
• Note if selecting neutral reduces the vibration/noise level (try to maintain road speed)
• Measure the cabin noise/vibration levels using a 3-axis accelerometer and microphone (3-axis plus single channel mode) The Mic will allow you to narrate "events" during your road test, which is ideal when playing back the captured data
• Once you have identified the offending axis (displayed when the noise/vibration is at its peak) switch to “multiple sensor mode” and add an accelerometer outside the vehicle.(Keep one accelerometer in the cabin measuring the offending axis, this is your reference)
• Ensure the added accelerometer is mounted in the correct orientation and the relevant offending axis chosen for measurement matches the offending axis measured in the cabin
• Use multiple accelerometers in the same fashion as above or a single accelerometer as a stethoscope. N.B. multiple road tests will be required and notes must be kept to denote where accelerometers were installed. (Use the notes section of the “Set-up” tab)
The following forum posts will help in addition to the items above:
When it comes to listening to accelerometers for “suspect” wheel bearings and tyre noise, mounting the accelerometer on a caliper bolt works perfectly
I hope this helps, take care…….Steve
First I’m away at work and will only be able to complete the testing you require at earliest Thursday next.
I’m going to try answer your questions and Have a few I’d like to ask you if you don’t mind?
1. Yes, definitely correct orientation.
2. My ears tell me it’s not there during a free rev, but I’ll double check with NVH gear.
3. I’m able to bring across from memory 6 harmonic rulers how do you get 32?
4. No recent work
5. About 2 months back but being a mechanic and owning the vehicle I’ve down nothing about it…it seems to be getting worse, so I thought I better get to it.
6. Is it temp related no I can hear it as I first drive off…it seems to me more prone Ed on desal
7.Yes I can confirm same orientation hole facing forward, second sensor/chD the z-axis was selected, from the results of the first test with high vib’s on chC the z-axis
8. I had both sensors oriented the same way hole to the front, chD into the z-axis and yes I believe the noise is there but not as pronounced as during desal.
9. Unfortunately I don’t have the mike records, I’ll only be able to access them Thursday next.
Thanks for taking the time to answer, I’ll redo all the testing Thursday next and upload the files with particular care on the notes
Yes! Kev you not wrong he is a master!
Above everything else, this is your wife’s car and we need to get it sorted as none of us need that kind of pressure!!
I speak from a recent experience of misdiagnosing my wife’s car for an airflow issue which I will share in another forum post ASAP (Very embarrassing indeed)
Regarding multiple harmonic rulers, this forum post has the information required
Catch up soon, take care……Steve
I have run-out on the front tyres of 2mm see attached. I've never measured tyre run-out before I was quiet surprised at the results!
(internet search says this is acceptable?? spec says max allowable 0.125 of inch. 0.125 * 25.4mm = 3.125mm?? seems a lot to me)
No wear or play in any of the wheel bearings tie-rod or ball joints. Rotating tyres when jacket up doesn't reveal any audible noise.
I have taken multiple runs today see attached, I still can't identify anything obvious. The z-axis between 75 ->104 hz stands out to me in ever capture but I can't seem to reference it to anything??
I was thinking of rotating tyres front l/h to rear r/h and front r/h to l/h rear and see if I get a audible difference.
all attached files taken with accelerometer mounted on inner seat rail drivers side, hole facing forward & mic attached to the rear view mirror. (I would say chosen road surface is good to very good)
Any insight would be greatly appreciated!