2016 MKX rear suspension issue?

[Dewey]

At 60 mph or slightly under 100 kph there is a vibration/bounce that feels like wheel balance. The wheels have been replaced and balanced. Could the fancy shocks be a possibility 54000kms on vehicle. Or maybe a wheel bearing? No noises just a vibration in the seat of your pants and only noticeable at certain speed.

 

[bbf2530]

At 60 mph or slightly under 100 kph there is a vibration/bounce that feels like wheel balance. The wheels have been replaced and balanced. Could the fancy shocks be a possibility 54000kms on vehicle. Or maybe a wheel bearing? No noises just a vibration in the seat of your pants and only noticeable at certain speed.

Hi Dewey. Still within the 4 years of the 4 year/50,000 mile New Vehicle Warranty? If yes, make an appointment for a proper diagnosis and service.

If not: Although there are various and many possibilities, let's stick with the wheel balancing for a moment, since it would be the easiest to isolate and cure. Were they "Road Force Balanced", or just given a traditional spin balance?

If they were not Road Force balanced, I would recommend finding a good shop that will do so.

Spin balancing can let many wheel and tire issues slide by. Things such as bent or out of round wheels, out of round tires, defective tires etc.

The easiest way to explain it in a rough analogy? Even a cinder block can be spin balanced, if enough weights are added. But we all know that same"balanced" cinder block will not roll smoothly, even if it has been spin balanced.

If this is out of your own pocket, I would recommend starting there.

If it is not the wheels/tires...Do you only feel the vibration in the seat of your pants? No visible steering wheel shake? No change/less/more vibration if you apply the brakes?
Also, try putting the transmission in Neutral (Carefully!), while you are at speed and feeling the vibration. Any change?

I asm sure others will have some good advice, so keep us updated and good luck.

 

[Dewey]

Thanks for the input. Yes all have been Road Force balanced.
A little more info: Situation came to light when I put the winter wheels and tires on. Went from the 21” factory rims to equivalent diameter 18’s in steel. RF balancing revealed problems with the steel rims which could never be solved. I purchased a set of FAST aluminum rims to hopefully eliminate a problem. It’s “better” but not cured.
The only elimination step I haven’t done is to put the factory rims back on. Lots of salt on the roads up here so not inclined to try this at this time but realize this should be performed.
I should mention the tires are high end Continental winters.

 

[bbf2530]

Thanks for the input. Yes all have been Road Force balanced.
A little more info: Situation came to light when I put the winter wheels and tires on. Went from the 21” factory rims to equivalent diameter 18’s in steel. RF balancing revealed problems with the steel rims which could never be solved. I purchased a set of FAST aluminum rims to hopefully eliminate a problem. It’s “better” but not cured.
The only elimination step I haven’t done is to put the factory rims back on. Lots of salt on the roads up here so not inclined to try this at this time but realize this should be performed.
I should mention the tires are high end Continental winters.

Hi Dewey. Blind Internet diagnosis? Yes, if you did not have this issue with the factory wheels/tires, then it sounds like a problem with the aftermarket wheels/tires. Unfortunately. Or perhaps fortunately, since it is likely not an issue inherent to the vehicle itself, which would be more difficult to diagnose/solve.

Have you tried marking and rotating the aftermarket wheels/tires to different positions (front/rear/left/right), to see if you can isolate it to a particular bad wheel/tire?

A wild, but educated guess is that the problem will go away when you reinstall the factory wheels/tires.

One other thought: Not sure where you live and how much snow is on the ground, but is it possible this vibration is caused by snow packed into the wheels, throwing the balance off? I know it is extremely unlikely, unless you are driving in deep snow all the time. However, it does happen, so is worth mentioning.

I'm sure other members will jump in with more suggestions/help.

Keep us updated and good luck.

______________________________

 

[enigma-2]

If it only occurs at a certain speed, wheel balance.

Weights need to be placed on BOTH sides of wheel (inside and outside) to resolve. Probably getting side-to-side out of balance.

 

[Dewey]

So, decided I’d get a professional opinion. My local go to guy (very good) kept it a couple of days, put the summer wheels on to eliminate. Ran in gear on lift.
His best guess is one or both rear cv shaft s. As a 2016 with only 50,000k 30,000m it would make sense that it sat for a long time at some point. The theory is perhaps the CV joint developed a “stiff” spot from sitting in one place for a long time.
Anyway the shafts are apparently fairly cheap only from the dealer, labour 5-6 hrs.
So for now winters back on, and drive till spring when I’ll probably pull the trigger on the shaft replacement.
On a side note, wholly crap the OEM 21’s are HEAVY!! lol

 

[bbf2530]

So, decided I’d get a professional opinion. My local go to guy (very good) kept it a couple of days, put the summer wheels on to eliminate. Ran in gear on lift.
His best guess is one or both rear cv shaft s. As a 2016 with only 50,000k 30,000m it would make sense that it sat for a long time at some point. The theory is perhaps the CV joint developed a “stiff” spot from sitting in one place for a long time.
Anyway the shafts are apparently fairly cheap only from the dealer, labour 5-6 hrs.
So for now winters back on, and drive till spring when I’ll probably pull the trigger on the shaft replacement.
On a side note, wholly crap the OEM 21’s are HEAVY!! lol

Hi Dewey. Your decision to "...get a professional opinion" was a great idea!

Hope it all works out. Keep us updated and good luck.