Repetititve shudder

[ukrkoz]

Hi all
Son has several months old T3.
According to him, it was driving like on glass, until 3 weeks back.
He did tire rotation about 2 or so month ago.
He did cross rotation.
3 weeks ago he noticed a repetitive shudder felt in the front and steering.
I drove car yesterday on various roads. Wavy, smooth, inclines, declines, regular speeds and FWY.
I can confirm that indeed, there is noticeable but faint shudder, about 3 times, every about 10 or so seconds.
3 times it was very pronounced, entire front and steering wheel shuddered violently. That reminded me of infamous Chevy trucks death wobble, related to bad idler and Pitman. .
So far, son had 2 technicians come over and inspect the car. One came with balancer and stated that all tires are balanced. The other tech argued that tires were not properly rotated and car is rumbling due to changed lugs direction. Same tech said that there is no foam inside Michelins on the car - there is. They took one tire apart and foam was inside. That made my son believe that that tech is not quite well verse on the matters.
That said, I work on my cars since 1990 and am pretty good at diagnosing shakes and vibrations.
I can confirm that there is a faint but very annoying cyclic shudder in the front lower end. That shudder may turn very pronounced without any pattern and at various speeds.
Son says it does it primarily at 45mph. Not my observation and I drove car for about an hour yesterday.
I have theory that one of the foam blocks delaminated inside and is bouncing, causing disbalance. That's my theory. Or, he has ripped cord of delaminated tire with mild hump in it.
Anyone else experienced similar?

 

[rincewind]

I'd suspect an out of round tyre (tyre = uk speak )

How about rotate them front to back again and see if the problem goes away?

 

[ukrkoz]

We considered that yesterday. I have car lift, we'll get her up Saturday, give it a spin. Yes, I am familiar with tyre, boot and bonnet. And petrol. Years of Top Gear.
Something is loose to cause rhythmic unbalance. Loose enough to cause small AND large shudder.
personally, I lean towards foam inside the tyres -))

 

[Paddy3101]

Lane departure warning will cause an intentional shudder when un-intentionally moving out of your lane without signalling.

Not repetitive though, but could be the more pronounced shudder you feel. Easy to disable in the menus to eliminate that from the equation.

 

[ukrkoz]

200% not lane departure. As in - POSITIVE.

 

[G26okie]

Make sure the lug nuts all torqued to about 129ft lbs, and it could definitely be the foam became detached inside one of the tires.

 

[ukrkoz]

We plan on moving tires around to see what happens. Also, we want ot get car up in the air and spin wheels with motors. If there were any out of round tires, it'd show.
But that's Saturday, my week days are too much to do that.
I simply don't trust "foam inserts". Too much variables to dislodge them. I also found a post here about similar situation and foam involved:
Acoustic foam detached from Michelin Primacy tire

We also have force balancer not so far away. Last resort, of course.

 

[TLLMRRJ]

Treat it like any other car then. Remove the lower aero panel and check the ball joints and bushing for play, and then retorque the suspension.

Remember, those factory workers in California are mentally out to lunch most days and they often forget to tighten things and put screws and fasteners where they belong. So you or the SC's need to "finish the build" sometimes. I know I did on several items on my Model 3.

 

[TLLMRRJ]

Make sure the lug nuts all torqued to about 129ft lbs, and it could definitely be the foam became detached inside one of the tires.

I would wager against foam being the problem. First of all, it's basically air, so it doesn't weigh much to shake a whole car like the death wobble. Second, at any speed, it will be firmly stuck where it is from the centrifugal force so it's not going to move around and cause the wobble to come and go while driving down the road.

 

[ukrkoz]

Foam or not, it went from smooth on glass to annoying shudder with jumps into mild eathquake. So something did shift somewhere and it does feel like tire related.

 

[G26okie]

I would wager against foam being the problem. First of all, it's basically air, so it doesn't weigh much to shake a whole car like the death wobble. Second, at any speed, it will be firmly stuck where it is from the centrifugal force so it's not going to move around and cause the wobble to come and go while driving down the road.

I've seen posts/reports from other owners where the foam became detached and balled up inside the tire leading to bad vibration.

 

[Paddy3101]

Foam or not, it went from smooth on glass to annoying shudder with jumps into mild eathquake. So something did shift somewhere and it does feel like tire related.

If the tires were checked, and are balanced, then can probably rule out the balance of the wheel/tire, unless you don't believe the results, in which case, take it somewhere else to get double-checked.

While there, get the alignment checked (4 wheel). Will indicate if hit something (pothole) and it's out of alignment. Will also probably detect if something's loose.

Careful putting the car up on a lift yourself, make sure you have the right lift points/pads.

 

[ukrkoz]

We already had her up on the lift. Son has those special lift pegs.

 

[ukrkoz]

Ok, update.
We had her up and examined tires. Best we could do without lasers, we found one tire with definite low spot.
He also had wheels force balanced and found no anomaly.
We then rotated tires side to side.
Son says, it is much better. I didn't drive her, so that's his opinion.