Imbalance and great confusion

Hello,

A sense of helplessness is slowly creeping in. I occasionally experience a significant imbalance in the front axle (which is strange because it happens sometimes, and other times not for a while), usually between 110-120, but also sometimes between 130-150.

After that, we started exchanging various things, since it didn't cost me anything anyway.


- Complete set of alloy wheels for exchange with new ones (i.e., brand new from the store, without any damage).
- New front tires (Bridgestone Turanza ER300)


Further tested and with very few kilometers driven.

- all axle bushings.
- Fahrwerk (org. (SEAT)
- Ball joints
- Tie rod ends and steering linkages.
- Measure track alignment.


After I bought new tires, everything was fine for a while (about 500 km), but now the wobbling has started again. I'm slowly at a loss and suspect that it might not be related to the rims or tires anymore.

Do you have any more ideas?

Have you ever measured the wheel hubs for runout?

No, not yet. We don't even have the tool for that, so I need to check with SEAT. Would this be a temporary phenomenon, meaning it comes and goes? Or would it be a permanent imbalance?

Generally speaking, the front axle is in good condition; all the bearings are new, and one of the driveshaft joints is also new.

Since the imbalance comes and goes, I also considered whether the balancing weight on the drive shaft might be shifting.

Quote:

It was good for a while (500 km), but now it's wobbling again. I'm slowly at a loss and suspect that it might not be related to the rims or tires anymore.

Well, if things were really quiet for a while, it actually suggests that something is about to go wrong again, or that there's an imbalance present. But why after such low mileage?
I would first re-check the front wheels for roundness and imbalance, even if they are relatively new. If possible, balance them to zero grams afterward, but first determine how many grams of imbalance are actually present. Then, continue to observe what happens. If the vehicle then runs smoothly again for a while, the cause must be found. What about the vehicle's geometry? Does the imbalance always occur, or only under certain load conditions, such as during acceleration or in coasting mode, or even when the vehicle is idling and rolling?

BM wrote:

"But why after such low mileage?"

"Normally, this issue has been happening repeatedly every 2-3 months for about a year now... But just before a long road trip, I bought new tires and the very next day, after driving about 600 km on the highway, it started again. The first few kilometers were fine, but then it began around 500 km into the journey."

Then it got better again, but on the way home it started hopping again, even at 140 km/h.

BM wrote:

I would first check the front wheels again for roundness and imbalance, even if they are relatively new. If possible, I would then balance them to zero grams, but first determine how many grams of imbalance are actually present.

Here's what I plan to do today, but I'm wondering: how can the balance shift so quickly? They were perfectly balanced at 0 grams initially, and they ran smoothly at first. And these are good quality tires.

BM wrote:

What about the geometry of the vehicle? Does the imbalance always occur, or only under certain load conditions, such as during acceleration or in "pushing" mode, or even when the vehicle is idling and rolling?

You probably mean the chassis/frame when you say "geometry"? The car is accident-free and was just aligned on the day of the tire change. Here are the alignment data for the front axle (the rear axle cannot be adjusted and is completely within tolerance), in case it's relevant:


Track VR: +00°04 (Tolerance range: -00°05 to +00°05)
Track VL: +00°04 (Tolerance range: -00°05 to +00°05)

Total deviation: +00°07 (tolerance range: -00°10 to +00°10)

Tilt angle: -00°25 (tolerance range: -00°30 to +00°30)
Tilt VR: -00°26 (Tolerance range: -00°30 to +00°30)



How about my theory regarding the balancing weight on the driveshaft? According to my SEAT contact, the wheel bearings and outer CV joints are also possibilities, but on one hand, both are relatively new (wheel bearings: 70,000 km, CV joint: 20,000 km), and on the other hand, there are no signs of wheel bearing problems like noises or rumbling when turning.


Before I forget: the centering rings of the alloy wheels are fine and undamaged; that was the very first suspicion.


Greetings.
George.

Quote:

How about my theory regarding the balancing weight on the drive shaft?

Possible, but doesn't fit with the 500 km of driving done with new tires.

Quote:

BM wrote the following:: What about the geometry of the vehicle? Does the imbalance always occur, or only under certain load conditions, such as during acceleration or in coasting mode, or even when the vehicle is idling and rolling?

Unfortunately, you have not yet provided us with the answer regarding the load conditions.

"Oh, sorry, I must have missed that."

Imbalance is independent of throttle position, rolling starts, or even being disengaged or idling while rolling.

Currently, there is growing suspicion that the new tires are rotating on the rim... therefore, today we first marked lines on the tire with chalk to detect any "wandering." This would explain why sometimes braking or strong acceleration temporarily resolved the issue.

Today, I simply didn't have time to balance the wheels. I'll re-balance them tomorrow and then I'll see if anything is missing; right now, it's still bouncing quite a bit.


I'll double-check it again tomorrow just to be sure.

- Ball joints
- Tie rod ends.
- Control arm bushings.

Although all of these parts are relatively new.

I haven't had a chance to get the wheels balanced yet, but the vibration is gone again – after a hard braking maneuver.

Now it seems the suspicion that the tires are slipping on the rims is becoming more concrete, so I've applied some oil-based chalk marks to make it possible to check the position of the rim and tire.

Okay, let's talk to the experts: When I mount a tire, what is the "tolerance range" I have left and right when it comes to positioning the weights? In other words, if the tire were to really "slip," how many centimeters would it need to slip before I would notice something?

Hi,

It's entirely due to the weights that are glued to the wheel. And then it depends on whether the imbalance is caused by the rim or the tires. If it slips about 180 degrees, you should be able to notice it.

In my opinion, the idea of shifting the tire on the rim is nonsense - unless your tire technician uses an inappropriate lubricant that provides permanent lubrication. I once encountered this with a 996 Turbo. However, different forces are at play in your case.

Greetings.

I am aware of this, and the mechanics at SEAT are too, that this case is extremely rare... but it's now the only explanation I can think of for why a balanced tire repeatedly becomes unbalanced again. I mean, if it's definitely not due to the rim and tire, then it can really only be caused by this.

Everything else in the drivetrain is fine; I checked all the joints again today.

Hello!

Just a thought.
If the imbalance disappears after a strong braking maneuver, and the frequency of the imbalance matches the rotational speed of the wheel, then could it be caused by the brakes? When was the last time you checked or replaced the brake discs/pads?

I'm experiencing the same problem, but at speeds of 80-100 km/h. I haven't been able to identify the cause of the imbalance yet, and therefore can't fix it.

Best regards.
Peter.

The brake pads/discs have been used for 25,000 km, the brakes don't pulsate, and they are high-quality original equipment parts from TRW.

Sometimes, the imbalance can be temporarily eliminated or reduced by applying a short, firm brake.

However, in my opinion, it has nothing to do with the braking system, because the brakes are running smoothly and are relatively new.

...

Sometimes, the imbalance can be temporarily eliminated or reduced by applying a short, firm brake.


Remove the brake discs, remove any rust/dirt, and thoroughly vacuum them clean. Then, secure the brake disc with a new centering screw.

It seems that the old problem still persists... There was even a Volkswagen service instruction about it.

@goettmann

Is it typical for this 'old error' that the imbalance occurs at specific speeds? That is, not under AND! above this speed range!

Thank you & best regards.
Peter.

PS: I'll try the cleaning method myself.

Is it typical for this 'old error' that the imbalance occurs at specific speeds? That is, not under AND! above this speed range!


Yes, that could be the case. The impurities are so minimal that you can barely see them. But eventually, the 'system' of the vehicle's suspension will reach a resonance point, and then the car will behave like a boat.
Very unpleasant.

But the error might not be here... it was just an idea, as I've experienced this issue several times before... I also know someone in this forum who keeps having this problem .

EDIT: One more thing...

What do the drive shafts look like? Volkswagen had some unusual issues with them in the past. Unfortunately, the only way to test them is by replacing them. But when they're bad, you can always feel it – there's a lot of play.

Hello,

Okay, I'm ruling out the possibility that something went wrong because I disassembled the brake myself and meticulously cleaned it with a polishing cloth (the contact surface between the hub and the rotor).

However, I can take a look at it tomorrow and see if I can figure out what's wrong, if I have time.

The constant velocity joints are slowly losing their plastic coating and starting to corrode, but they are still solid. I actually replaced an outer joint over the winter because it would click when turning and made unpleasant humming noises.

The other joint was examined and found to be in good condition.