Wheel Alignment: Geometry, Straight Tracking & Tire Wear

Hello everyone,

Before I take my car for a wheel alignment, I want to do some more research because I'm starting to not understand the logic behind it anymore.

But let's go step by step:

My old Continental summer tires were so worn down that the tread depth was about 1.5 mm shallower on the outside than on the inside. Additionally, the car tended to drift slightly to the right when I released the steering wheel. At that time, I had the tire pressure set to 2.6 bar to save fuel.

I had planned to have the geometry checked when I switched to the WR tires, but I never got around to it, and then I forgot about it because the straight-line stability was absolutely excellent. In the 5,000 km that I've driven on them, there has been a difference in wear between the inner and outer edges of less than 0.1 mm (for comparison: the Contis were used for 20,000 km both front and rear, which is "only" four times this distance, but with fifteen times more asymmetry in the wear).

"Yesterday, I finally got the new summer tires installed (after a long consideration - see the tire thread - and due to the unfavorable dimensions, I went with Continental Premium Contact 2 again because the driving characteristics are simply extremely good, especially in wet conditions and during braking). This time, I set the pressure to the standard 2.2 bar (inspired by a comment from Bertil in the LLR thread about finely balanced systems), but I have the impression that the car is pulling slightly to the right again when you release the steering wheel. It's less than with the old Contis, but more than with the winter tires (Goodyear UG7), where I didn't notice anything like that."

To prevent uneven tire wear in the future, I want to get to the bottom of this issue. The mechanic I contacted about the cost of a wheel alignment explained that during acceleration, the front of the car is unloaded, which increases the camber of the wheels and puts more stress on the outer edges. A similar effect occurs during high-speed highway driving. While this sounds logical, it should also affect winter tires and all other TDI models.

I should also mention that the driving style remains unchanged – so I still occasionally use the ASV's 235 Nm of torque and its top speed of almost 200 km/h, but I don't do any drag races or aggressive cornering. The winter tires saw less mileage than usual (due to fewer long trips last winter) and were also used at slightly lower speeds because they only have a T-rating.

Well... if you add it all up: system error, incompatibility, or perhaps a misaligned geometry? Regarding the latter, I don't think it fits, considering how well it works with the WR (presumably referring to a specific device or software).

Goodyear tires are directional, while Continental tires are not, although they don't have a perfectly symmetrical tread pattern (meaning the arrangement of the sipes differs on the left and right sides in relation to the road and direction of rotation). Combined with the fact that roads are never perfectly straight (and often slope outwards for water drainage), this could potentially explain the currently very minimal straight-line running error. The Continental tires are much harder than the Goodyear tires, which might make them more susceptible to this issue.

What do you think?

As I said... I want to get it measured, but I still want to learn more about it beforehand and let the tires break in for at least two weeks.

Best regards,

Jan.

P.S.: When braking and accelerating, the car goes perfectly straight, regardless of the tires used.

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As I said... I want to have it measured, but I still want to know more about it beforehand and let the tires break in for at least two weeks.

Several factors are involved here. However, I would like to state that the increased outer tire wear is primarily caused by what's known as "rolling." When driving quickly through curves, the vehicle leans around its longitudinal axis towards the outside of the curve. This lean also affects the camber on the outermost wheels. The McPherson suspension system cannot fully compensate for this in normal circumstances; therefore, the outermost wheels experience a more positive camber during fast cornering, which leads to increased tire wear.
Then the quality of the tire sidewall and its load-bearing capacity also play a significant role, etc., etc.

You could have the car's alignment checked at a reputable workshop, but if the tire only shows increased wear on the outer edge and otherwise wears evenly, I doubt this will be successful. Perhaps you could adjust the camber slightly closer to the negative tolerance limit.

Hi,

I assume that with your virtual alignment (VA) system, only the track can be adjusted. The tilt can only be corrected by shifting the auxiliary frame.
I would like to point out that the Premium Contact tires I have (205/55R16) must have a very stiff sidewall. The vehicle follows ruts in the road very strongly – whereas with my previous 195-size winter tires, one finger was enough on the steering wheel, now you almost need both hands. The influence of uneven surfaces is very significant with these tires. This results in the vehicle constantly pulling to the right, because most roads have a slight slope to the right. I assume that the new Premium Contact will exhibit the same direct behavior. Therefore, everything should be fine.
However, a wheel alignment is never really harmful.

Best regards,
Matthias

PS: On my old vehicle, the tires were also noticeably more worn on the outer edges. However, this was due to the many fast turns I took. The axle was designed for a different driving profile.

Hmm.

I had the impression that the PremiumContact tires were more on the soft and comfort-oriented side.
With the Bridgestone ER300 tires, I was able to navigate corners around the G3Var much more effectively.

And last summer, I was allowed to test three complete sets.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hmm,

'Perhaps your Bridgestone tires are even harder. I haven't had the chance to test many different tire models yet. However, I know from my old car (all with 195/65R15 tires) that the Michelin Alpin 2 WR winter tires were stiffer than the Continental Eco Contact tires.'
I understand that some of the stiffness in my current premium tires comes from the fact that they are now 205/55R16 instead of 195/65R15 (my Dunlop WR tires for the Passat). However, overall, they still have a very stiff sidewall.

Best regards,
Matthias

'A long time ago, I once had 195/60R15 tires on a Vectra A. When I got a flat tire on the front, the rim's inner edge didn't touch the tire's tread surface. The sidewalls were still able to keep the vehicle somewhat elevated. That's what I would call a stiff sidewall.'

Um... excuse me.

Comparing winter tires to summer tires is not a fair comparison.

My 205/55 R16 94H Dunlop winter tires are also harder than my 235/45 R17 97W Continental SportContact2 summer tires, even though I would have expected the opposite based on the dimensions.

@ Jan
I've always wondered why the Continental Premium Contact tires are directional, even though they rotate side-to-side.

The outward drifting is certainly due to the curve-taking behavior that aligns with the Seat brand image .

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Or the Ibiza is too heavy in the front, and the cornering speed isn't high enough, which then still encourages body roll when turning.

I've experienced this firsthand (not on my own car), and I've learned that adjusting the alignment is an art form that not everyone masters, and unfortunately, the quality of the work isn't always immediately apparent.

@Martin
'Actually, sports tires are always better to drive – especially because of their direct handling. My intention with the comparison was simply to show how awful the EcoContact tires are. Of course, the rolling resistance and road noise are excellent with the EcoContact, hence the name.'

I'm also not entirely sure about the outside/inside aspect, because on one side, even if they are small, the angled grooves might actually promote aquaplaning, although that's not a quantifiable statement.

Hi,

Wow... you guys are working hard... so, let's go in order:

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When driving through curves at high speeds, the vehicle tends to lean around its longitudinal axis towards the outside of the curve. This leaning also affects the camber of the wheels on the outer side of the curve. The McPherson suspension system cannot fully compensate for this in normal circumstances; therefore, the wheels on the outer side of the curve experience a more positive camber when driving through curves at high speeds, which leads to increased tire wear.

Hmm... I either use it for city driving or, less frequently, for long distances. Really enjoying fast cornering on scenic country roads is a very rare occurrence.

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You could have the car checked out at a good workshop, but if the tire only shows increased wear on the outer edge and otherwise wears evenly, I doubt this will be successful.

Well... there was definitely a certain degree of linearity visible, not just at the edge. The profile improved towards the inside. As I mentioned before, the WR values were perfectly within the standard range and showed virtually no difference.

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I would like to point out that the Premium Contact tires I have (205/55R16) must have a very stiff sidewall. The vehicle follows ruts in the road very strongly - where with my 195s, one finger is enough on the steering wheel, now you almost need both hands. The influence of uneven surfaces is very high with these tires. This results in the vehicle constantly pulling to the right, because most roads are slightly inclined to the right. I assume that the new Premium Contact will exhibit the same direct behavior. Therefore, everything should fit properly.

That completely aligns with my observations, including the tire tracks.

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I had a different impression of the PremiumContact; I thought of it as being softer and more focused on comfort.

My comparison is with WR tires... they are definitely softer than the Continental ones.

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The "outer lane driving" is likely a result of aggressive cornering that aligns with the brand image of SEAT.

No... you... then the WRs would have to do it too.

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Or the Ibiza is too heavy in the front, and the cornering speed isn't high enough, which then still encourages body roll when turning.

"800 kg at the front, 400 kg at the rear... that should already be enough to make it 'too heavy', right? The cornering speed isn't usually very high, even if the suspension allows it: On the endless curve and the slalom track at the ADAC facility in Linthe, I achieved similar results with the Goodyear tires as the others, often even slightly better (except for a sports car, but that doesn't count)."

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I've experienced this firsthand (not with my own car), and I've learned that adjusting the alignment is an art form that not everyone masters, and unfortunately, the quality of the work isn't always immediately apparent.

So the lesson is: get it measured, but don't let anyone modify it. Although Matt is probably right... there won't be much to adjust. It's a hybrid of a Polo 6N, a Golf 2, and a Golf 3.

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I'm also not entirely sure about the outside/inside aspect, because on one side, even if they are small, the angled grooves might actually promote aquaplaning, although that's not a quantifiable statement.

It's probably due to aquaplaning because of the large grooves, but that also causes the rest of the tire to wear unevenly.

@Everyone: What influence do you think air pressure has on this? The old Continentals had 2.6 instead of 2.2, the winter tires were always at 2.2 (and just wore out), and the new Continentals initially also had 2.2 (which is what I told the tire shop, but they actually put in 2.4).

Best regards,

January.

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Before I take my car for a wheel alignment, I want to do some more research because I'm starting to not understand the logic behind it anymore.

Sometimes there's a certain amount of illogicality involved, as these are dynamic processes that can't always be immediately recognized through static views.

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... This time, I adjusted the pressure to the standard 2.2 bar (inspired in part by a comment from Bertil in the LLR thread about finely balanced systems).

Here's a quick note: The correct tire pressure should always be specified by the tire manufacturer, based on a load table specifically designed for that particular tire construction. Simply put: the more weight the tire carries, the higher the tire pressure needs to be. The tire pressure recommendation from the vehicle manufacturer is a very general guideline and not necessarily accurate (although it's often correct).
I've noticed that many caravan manufacturers specify tire pressures that are far too low.

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... but I get the impression that the car tends to drift slightly to the right if you let go of the steering wheel. It's less than with the old Contis, but more than with the winter tires (Goodyear UG7), where I didn't notice anything like that.

So ein Problem hatte ich vor 20 Jahren auch mal. Ich habe mich beim Reifenhändler beschwert und der hat dann einen der beiden Vorderreifen auf der Felge gedreht. Error gone!
The dealer explained to me that the manufacturing process of the tires can sometimes result in a situation where the load-bearing capacity of the two sides is not perfectly symmetrical. If you now position the tire with the "softer" side towards the right, it could cause the car to exhibit behavior similar to what you described – pulling into a curve. Rotating the tires on the rim will then compensate for these asymmetries in both tires.
However, this only works with tires that do not have a directional tread pattern.

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To prevent asymmetrical wear in the future, I want to get to the bottom of this issue. The mechanic I contacted about the cost of an alignment gave me the following explanation: When accelerating, the front of the car is unloaded, which increases the camber of the wheels and puts more stress on the outer edges.

Oh dear... Suspension geometries. It's been a long time . I'll try to recall it.
So... the blame for such "external flank effects" is not only due to the camber angle. Especially in front-wheel drive vehicles, it's actually less of a factor, as the camber change with a McPherson strut during acceleration isn't that significant. Much larger are (in this particular design) the changes in track width caused by the drivetrain influences.

It is a characteristic of all cars that the front wheels (when viewed from the direction of travel) tend to diverge outwards (toe-out). This effect is counteracted by adjusting the toe angle accordingly. That's the theory for passively rotating wheels.
Unfortunately, with front-wheel drive, the driving forces also come into play. These forces unfortunately cause the front wheels to pull inwards. Now, a compromise must be found for the axle geometry.
The values for toe-in are largely constant (and well-known) due to the rolling resistance and can be determined relatively easily. However, the correction values for toe-out are extremely driver-dependent. If a driver "presses the accelerator heavily," the toe-out behavior becomes significantly more extreme. This would mean that a more sporty driver may need to set slightly more toe-in compared to an average driver.
The typical compromise for front-wheel drive vehicles is to set a slight amount of toe-in.
Okay, and now things are about to get really interesting. The type of tire used also plays a role. Some tires have a geometry that puts undue stress on the wheel alignment, making the tendency for toe-in or toe-out more pronounced. This can then lead to uneven wear on the outer edges of the tire treads.
The wheels used also play a role here. Wheels with extremely low offset values put additional stress on the wheel suspension and can suddenly cause some strange wear patterns on the tires, especially during dynamic driving conditions.

Excessive toe-out -> increased wear on the outer edge of the tire.
Too much back trim -> increase the closure on the inside.

Attention: The above analysis is highly simplified! In extreme cases, especially when driving on curves, other parameters come into play.

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... Well... if you add it all up: system error, incompatibility, or perhaps a misaligned geometry? Regarding the latter, I don't think it fits, considering how well it works with the WR (wave rectifier).

Especially since the WR is likely to be more "prone to sealing," I would have expected the phenomenon to be even more pronounced on the WR.
...

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Goodyear tires are directional, while Continental tires are not, although they don't have a perfectly symmetrical tread pattern (meaning the arrangement of the sipes differs on the left and right sides with respect to the road and direction of rotation). Combined with the fact that roads are never perfectly straight (and often slope outwards for water drainage), this could potentially explain the currently very minimal straight-line running error.

Please provide the text you would like me to translate from German to English. I will then give you only the translation, without any explanations.
I agree with you about the straight-line running issue; it's certainly not impossible.


I'd like to steer your perspective in a different direction, as I believe you didn't always have this "flaw."
Your car is subject to wear and tear. With every kilometer driven, there's a certain amount of degradation. For the geometry of the suspension, it's very important that the "load-bearing components" are in good condition. This includes the rubber bushings in the control arms, tie rods, etc. If these are worn out, you will experience significant dynamic deviations from your statically measured geometry values. Even if your axle geometry is correct, there can be noticeable deviations during driving, which can also lead to corresponding wear patterns on the tires.

As far as I remember, your IBI is on the 6-series platform, which is the same as our Lupo (which was significantly shortened and designated as a 6X). I had a problem with the rubber bushings of the triangular control arms. One bushing was torn out, and another was close to it. However, the axle geometry was still correct. If I had driven it for longer, I'm sure I would have noticed that the tires were wearing unevenly.
I had a similar problem with my Golf 4. In this case, the (rear) rubber bushings were probably worn out, and I had uneven wear on onetire. I replaced the rubber bushings, and the wear pattern became symmetrical again.


One more quick test before you have your axes measured.
If your car pulls to one side and you suspect it's due to the tires, try temporarily swapping the left and right front tires. If the car then pulls in the opposite direction, the problem is with the tires themselves, not the wheel alignment.

If your tires are okay, then I suspect the rear lower control arm bushings. They're so worn that your wider summer tires are pulling the axle geometry further towards negative camber due to driving forces.

Hello everyone,

@Bertil: Thank you very much for the very detailed explanations regarding the suspension geometry.

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So ein Problem hatte ich vor 20 Jahren auch mal. Ich habe mich beim Reifenhändler beschwert und der hat dann einen der beiden Vorderreifen auf der Felge gedreht. Error gone! ... However, this only works with tires that do not have a directional tread pattern.

...and not even with the Conti tires, because they are marked as "inside" and "outside."

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Especially since the WR is likely to be more "prone to sealing," I would have expected the appearance on the WR to be even more pronounced.

Me too... if it had been more dramatic, I wouldn't have even put it up for discussion; I would have just had it measured immediately.

However, I must also say that I have only driven about 700 km on the highway at high speed with the WR tires. In contrast, with the old Contis, over the 2 years they were on the car, I drove quite a bit and mostly pretty fast (170 to 190 km/h, sometimes for hours), totaling perhaps 10,000 km. According to Beril's explanation (regarding the effects of toe-in and toe-out), this effect should not only occur during acceleration but also during constant high-speed highway driving, because when the engine is running near its maximum power output, corresponding forces act on the wheel suspension for extended periods. The WR tires have mostly been driven at speeds below 100 km/h, except for those 700 km.

Wear and tear:

"Of course - a car that's almost 6 years old isn't new anymore after nearly 90,000 km. When I had the winter tires put on and the front brakes replaced at the same time, the mechanic pointed out that this type of suspension often has problems with the rubber bushings in the control arms, and that this can easily lead to a failed TÜV inspection (which was something I needed at the time). I asked him to take a look at it on the lift, but he didn't find anything like that (this was about 5000 km ago, AFTER the first set of Continental tires which were wearing unevenly). Of course, it's possible that he didn't check carefully, but since there's definitely money to be made by replacing those parts, I doubt that.

Is there a test that doesn't require a lifting platform, which could be used to determine the condition of the rubber components? Simply looking at them certainly won't be enough.

However, I believe that the wear and tear in that area should also have been caused by the inverter.

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If your car pulls to one side and you suspect it's due to the tires, try temporarily swapping the left and right front tires. If the car then pulls in the opposite direction, the problem is with the tires themselves, not the wheel alignment.

Without a ramp, it's not quite as easy - but I will do it if things turn out to go in that direction. Today, however, I tried something else: On a road where the drains are in the middle, the car pulls slightly to the left; on a rather rough highway exit (drains at the bottom), it drives perfectly straight. In a residential area with little traffic and drains on both sides, it also stays nicely in the center. I think that the imperfect straight driving is actually due to the Contis' sensitivity, even though the tests are not entirely conclusive, because the assessment at 40 km/h is quite different from that at 90 km/h. However, the trend is clearly visible, and I will continue to test this further - somewhere there must be a section of city highway (tunnel?), where they drain on both sides and you can test all three variants on the three lanes.

The right-hand turn might be slightly sharper than the left-hand turn, but that could be due to the road conditions, and possibly also due to the asymmetry of the Conti tires (identical profiles on all, but mirrored due to the inside/outside orientation).

I also accelerated with full throttle in second gear on a relatively straight stretch of road today, while keeping the steering wheel loose (i.e., so that you can quickly grab it ) - and it went perfectly straight. The same thing happened when braking hard.

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If your tires are okay, then I suspect the rear lower control arm bushings. They're so worn that your wider summer tires are pulling the axle geometry further towards negative camber due to driving forces.

That remains relevant regardless, because the uneven wear of the old Conti tires and the slight tendency to drift to the right are two different issues (or at least, I think so).

Regarding tires and rims: Everything is perfectly comparable here. They are the same type of rims (Seat's standard aluminum alloy wheels with 15 inches, 6J width, and 38 mm offset). The tire dimensions for both the summer and winter tires are identical at 185/55/15 - narrower tires are not allowed (at least not without some kind of approval), and wider tires are only possible on 16-inch rims, which I don't want because of the increasingly uncomfortable relationship between tire width and tire height.

Okay, I'll take a closer look at the wishbone suspension when I'm next at my workbench.

Best regards,

January.

Jan6K wrote:

... @Bertil: Thank you very much for the very detailed explanations regarding the suspension geometry. ...

Well... In the early days of my motorsports career, I had to deal with that.

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... According to Bertil's explanation (regarding the pre and post-trail), this effect shouldn't only occur during acceleration, but also when driving at a constant high speed.

Yes, exactly... The forces involved are also not insignificant.
Ulf might even be able to provide data based on the drag forces calculated from the digital terrain model (DTM).

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...because if the machine is operating in the Pmax range, then corresponding forces will act on the wheel suspension over a long period of time. The WR vehicles - aside from those 700 kilometers, which were mostly driven at speeds below 100 km/h.

Could confirm the suspicion of worn rubber bushings.

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Wear and tear: "Of course, a car that's almost 6 years old and has nearly 90,000 kilometers on the odometer isn't brand new anymore. When I had the winter tires installed and the front brakes replaced at the same time, the mechanic pointed out that this type of suspension often has issues with the rubber bushings in the control arms, which can lead to TÜV (German technical inspection) rejection. I asked him to check it on the lift, but he didn't find anything like that (this was about 5000 kilometers ago, AFTER the first set of Continental tires, which were wearing unevenly)."

Your mechanic is absolutely right... but unfortunately, the rubber boots are so well-covered that you might not be able to see the defects. The most practical thing to do is to pry off the control arms with a tire iron. This allows you to clearly see what's moving. With enough sensitivity, you can even feel the differences between the right and left sides.

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It's possible that he didn't look closely, but since there was certainly a lot of money to be made from it, I doubt that's the case.

Okay, if this were a really difficult or unpleasant task, I could understand it, but actually, it's not a major problem. Martin already described something similar in this forum regarding his Golf 3.

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Is there a test that doesn't require a lifting platform, which could be used to determine the condition of the rubber components? Simply looking at them certainly won't be enough.

Unfortunately not. A stage or pit is required. You have to use a crowbar or similar tool and really pry at it. A purely visual inspection isn't sufficient because it's too obscured.
Unfortunately, these are dynamic defects that only occur while the vehicle is in motion. You'll have to simulate those using a "breaker bar" (or similar tool).

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.... That remains relevant regardless, because the uneven wear of the old Conti tires and the slight tendency to drift to the right are two different issues (or at least, I think so).

It can also be caused by different types of seals used in the two bearings.
In the suspension system, parts on the right side typically wear out faster than those on the left. The reason is quite simple: the right side is closer to the "bad" edge of the road that the car often drifts towards. Consequently, the wear and tear is actually greater on that side.

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However, I also have to say that I only drove about 700 km of highway at really high speeds with the WR tires. In contrast, over the 2 years they were on the car, I drove quite a bit with the old Contis, and mostly pretty fast (170 to 190 km/h, sometimes for hours), totaling perhaps 10,000 km.

That's why I initially suspected that these were "rollers," as I assumed it was solely due to edge wear.

Later in the thread, it turned out that:

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Well... there was a certain degree of linearity to be observed, not just the edge. The profile improved towards the inside. As mentioned before, the WR values were absolutely within the standard range with virtually no difference.

As Bertil explained very well, the entire system should be considered dynamically. It's possible that there is wear on the axle suspension components, as the "hard" Conti tire, with its stiff sidewalls and wider tread, may transmit stronger and uneven forces to the axle compared to a balanced tire. This can cause the vehicle's geometry to change dynamically, potentially negatively affecting handling.

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The change in geometry at a McPherson strut during acceleration is not very large.

Significantly larger (in the design presented here) are the changes in track width caused by driving forces. }

Using softer rubber would further amplify the effect.

BM wrote:

... Using softer rubbers would further amplify the effect.

By the way, I just remembered something...
There are some models in the VW lineup that have had issues with the strut mounts. Unfortunately, I can't recall right now whether the 6K is also affected. If it is, then a dynamic camber change caused by faulty strut mounts could be the culprit.
Personally, I haven't experienced that yet. It doesn't seem to be a very common occurrence.

Hello everyone,

Sorry for the delayed responses... I haven't had time to write anything more than short messages these past few days.

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Could confirm the suspicion of worn rubber bushings.

It then concerned the front axle and the forces acting upon it. Shouldn't one be able to notice worn bearings in that case, through changes in steering behavior during acceleration or braking? In fact, there is absolutely nothing like that happening...

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The most practical way to remove the lower control arms is using a lever and a suitable fulcrum point.

So, you mean positioning them as close as possible to the bearings, ensuring that the rubber bands are stretched primarily in one direction, while also taking into account any potential play or slack?

"Actually, shouldn't it also work if the car is on its own wheels? Because I have lifting ramps, which should provide enough clearance (and especially safety), and the force that can be applied near the pivot point using leverage should be much higher than what the 200 kg per side (we're talking about the rear axle) can exert through the triangular wishbones. Or am I mistaken?"

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It can also be caused by different types of seals used in the two bearings. In the suspension system, parts on the right side typically wear out faster than those on the left. The reason is quite simple: the right side is closer to the "bad" edge of the road that the car often drifts towards. Consequently, the wear and tear is actually greater on that side.

However, I believe that uneven wear on the front tires, both left and right, which causes the car to pull to one side, would be most noticeable during braking or acceleration.

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It's possible that the wheel suspension components are worn out, as the "hard" Conti tires might transmit stronger and uneven disturbances to the axle due to their stiff sidewalls and wider tread pattern, compared to a balanced tire. This could dynamically alter the vehicle's suspension geometry in a negative way.

If I think about it further... then lowering the tire pressure from the 2.6 bar that I had with my old (worn) Contis to the standard 2.2 bar that I have now might be enough to shift things a bit closer to the behavior of winter tires. A difference of 2.6 to 2.2 bar is quite significant, and higher tire pressure definitely makes the tire harder.

Strut mount:

At least among all the 6Ks ever built, the variant with the ASV (presumably a specific component or system) and a lot of additional equipment is likely to put the greatest strain on the dome bearings. However, this should become apparent under load, right?

Best regards,

January.

Jan6K wrote:

... Quote: Could confirm the suspicion of worn rubber bushings. It then concerned the front axle and the forces acting upon it. Shouldn't one be able to notice worn bearings in this case, through changes in steering behavior during acceleration or braking? In fact, there is absolutely nothing like that happening...

Yes and no. You mention that the wear pattern indicates a leading-edge issue, but when braking, the bearings are likely to be loaded towards the trailing edge.
Unfortunately, these bearings can sometimes fail in such a way that only one direction of load is affected (e.g., the core separates).

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Quote: The most practical way to remove the lower control arms is using a lever and a suitable fulcrum point. So, you mean to position them as close as possible to the bearings, ensuring that the rubber bands are stretched primarily in one direction, while also taking into account any potential play or slack?

Sure.

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Actually, shouldn't it also work if the car is on its own wheels?

Whether or not the car is on top doesn't matter.

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"I have lifting ramps, which should provide enough clearance (and especially safety), and the force that can be applied near the bearing using a lever should be much higher than what the 200 kg on each side (we're talking about the rear axle) can exert through the triangular wishbones. Or am I mistaken?"

Rear axle?? Are you having a problem with the rear axle?
If so, I apologize, I must have missed something. However, this is a known issue with the 6N and when using various types of tires. The Golf 3 also had this problem.

Or have I misunderstood something?


Regardless, the force you apply with a wrench on the short section of the lower control arm is sufficient to determine if there's an issue.

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However, I believe that uneven wear on the front tires, both left and right, which causes the car to pull to one side, would be most noticeable during braking or acceleration.

See above for possible reasons why it might not be advisable.

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If I think about it further... then lowering the tire pressure from the 2.6 bar that I had with my old (worn) Contis to the standard 2.2 bar that I have now might be enough to shift things a bit closer to the behavior of winter tires. A difference of 2.6 to 2.2 bar is quite significant, and higher tire pressure definitely makes the tire harder.

While that's true, you would have had to inflate the softer winter tires to a significantly higher pressure than recommended.

Try it out. If it had any effect, you should be able to see it relatively quickly. That would be the simplest approach.

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Strut mount: At least among all the 6Ks ever built, the variant with the ASV (presumably a specific component or system) and a lot of additional equipment is likely to put the greatest strain on the dome bearings. However, this should become apparent under load, right?

The dome supports would definitely show this defect under any load (whether positive or negative).