Wobbly control arm bushings on Polo / Ibiza / Fabia

Hello,

In the Polo 9N platform, the rear transverse link bushings on the front axle are designed as soft rubber shims, which allow for approximately 1 cm of play in the transverse link, both inwards and outwards, and are a source of various clunking and creaking noises.
In the "Damaged Suspension" attachment, you can also see the typical points of failure in the vertical rubber supports (at the top), which may require replacement after only a few tens of thousands of kilometers.

As a solution, solid rubber bushings from the A2 model can be installed. In the 9N.info forum, these bushings are often praised for providing noticeably improved steering precision. Whoever wants to read that: CLICK

I'm now wondering what advantages the "Wabbel" suspension system actually offers, or what subtle (handling-related?) disadvantages one incurs when switching to A2 bearings.

From a handling perspective, imprecise rear axle mounting is a disaster. Lateral acceleration causes the rear to tilt into the bearings, which then react with a time delay, forcing load transfer reactions. This type of driving behavior, which often results in the rear end skidding out, can startle the average driver and provoke (possibly incorrect) reactions. This can lead to the danger of losing control. However, it can also be intentional, as a car that is too sporty and precise can encourage aggressive cornering, while a slight tilt in the bearings may actually encourage a larger portion of the customer base to drive more conservatively. These are just speculations!

From my youth, I remember that (amateur) rally cars (mostly Golf 2 GTI 16V models with a Syncro body) had their triangular control arm bushings and stabilizer bushings, as well as the strut mounts at the front, replaced with harder plastic bushings instead of rubber. These bushings were available in distinctive colors (for different hardness levels) under the brand name "JOM" (if mentioning the brand name doesn't fit with the board's preferences, simply delete it!). We tried all sorts of strut mounts available as accessories, and amusingly, the cheapest supplier was the one that offered the hardest strut mounts. The final stiffening of these mounts was achieved by filling the groove around the ball joint with adhesive. That was against the rules, but it was rarely noticed. At the rear, all accessible rubber bushings were replaced with plastic ones.

As a result, the modified vehicle could be driven more precisely and smoothly. Drifting no longer felt like a gamble, but rather became a controlled and safe maneuver. It's important to remember that these are amateurs driving, not professionals!

Hmmm... Our cars back then didn't have ABS, ESP, or any of those electronic driver assistance systems. These movable bushings might be part of the overall calibration for systems like ESP (Electronic Stability Program) and ABS (Anti-lock Braking System), although I can't imagine that anyone would intentionally install something like that.

I suspect that the softer bushings might be suffering due to excessive vibrations in the suspension on uneven road surfaces or cobblestone, while the stiffer Audi bushings might be transmitting more noise or vibrations to the body than the softer bushings from the VAG range.

In the same vehicle segment, I believe that Audi models have always been tuned to be slightly sportier than their counterparts from Volkswagen or Skoda. Often, SEAT also opted for a firmer suspension (subjectively), in order to emphasize the sportier character of the brand.

The average consumer often chooses the Skoda Fabia (based on price), while those who prefer something more individual and sporty tend to go for the Seat Ibiza. Those who want something more "reliable" usually opt for the Polo. Sure, it's a stereotypical view – but the design language, interior architecture, and overall appearance are what shape the image in your mind.

Ultimately, the only solution for those who like to tinker with their cars is to choose the best parts themselves and use them. Parts that were considered good enough by the manufacturer and its workshops may not appeal to someone who likes to customize their car. This is where online forums and online parts shops come in handy. Some shops even allow for cross-comparisons, making it easier to find alternative parts. And, especially for car enthusiasts, online forum members are often happy to share their experiences. It's great that we can benefit from this!

Hutfahrer wrote:

From a handling perspective, an imprecise rear axle mounting is a disaster. . . .

Thank you for your informative answer, but I'm talking about the front axle (VA), and specifically the rear transverse control arm bearings there.

I suspect these parts are simply cheaper to purchase. The Polo is a low-budget vehicle for the manufacturer. Perhaps different components are used in better-equipped versions.

However, I have to agree with "Hutfahrer" that a Polo with 160 diesel horsepower is a real beast. Even 130 horsepower is more than enough for such a car. Most likely, soft suspension components were installed for this very reason: to encourage the driver to adopt a more cautious driving style. ^^

I claim that manufacturing fully enclosed storage units is cheaper than manufacturing those with open compartments.
Then it has to do with the wheel alignment when braking and in curves, and not least, the wear pattern changes due to different wheel alignments under load.
In a vehicle with a solid rear axle, even the act of driving the wheels changes the camber setting. When braking, this results in increased toe-in because the trailing arms are compressed even further by the soft rubber bushings than they would be with solid bushings.
I don't believe that corrective or plastic bearings are necessarily the more honest choice when it comes to extreme riding. Where there is no give, there is no rebound; when the grip suddenly breaks and is re-established!
However, in the series, it is likely that the manufacturers of railway switches will receive more attention, as they are involved in the construction and maintenance of road and... Make tire noise inaudible and simulate a comfortable sound.
Ulf, with the power your engine has, you should try using stickier tires!

Hi,

I don't actually own a Polo, but I've already replaced these bearings on a Skoda Fabia .

Here's my short report about stiffer axle suspension parts:

In my Audi 80, the engine (like in all 4-cylinder models) is mounted on the front subframe.
which is attached to the longitudinal members with rubber bushings, and the control arms are then attached to this.
re-attached with rubber bushings.

It works reasonably well with gasoline engines, but not with diesel engines.
During gear changes, it felt like the engine was going to fall out (even with the small 1.6TD).

Since I securely fastened the frame with motorsport parts made of aluminum/stainless steel, and the...
I replaced the control arm bushings with polyurethane ones; one might think that...
sitting in a cart.

-no load change issues.
-No "kickback" from the suspension during the initial braking phase when performing emergency braking.
-No vague steering feel around the center position.

Those who are willing to accept slight compromises in comfort and appreciate a precise driving feel will find these PU bushings to be exactly what they need.

As soon as I get a rear axle with disc brakes, I will also mount it with polyurethane bushings, as they will now provide quite a bit of steering assistance.
Similarly, a solution is needed for the front shock absorber mounts, as these are sourced from the Polo 1: the rubber bushing is always defective after a maximum of 10,000 km.

They look like a good alternative to the A2.

Best regards, Michael.

EDIT: of course, the sound of the road got closer... it doesn't really interfere with the diesel engine noise, and it's also due to the modified springs/shock absorbers .

Okay, Ulf! I misread it.

teileklaus wrote:

Then it has to do with the wheel alignment when braking and in curves, and not least, the wear changes due to different wheel alignments under load. In a vehicle with a solid rear axle, even the act of driving the wheels changes the camber setting. When braking, this results in increased toe-in because the trailing arms are compressed even further by the soft rubber bushings than they would be with solid bushings. I don't believe that corrective or plastic bearings are necessarily the more honest choice when it comes to extreme riding. Where there is no give, there is no rebound; when the grip suddenly breaks and is re-established! However, in the series, it is likely that the manufacturers of railway switches will receive more attention, as they are involved in the construction and maintenance of road and... Make tire noise inaudible and simulate comfort.

That's closest to the direction I meant / suspected.
Abrasion is, of course, also an interesting (cost-)related topic: With full bearings, the pre- and post-wheelplay range would be significantly reduced, and my gut feeling is that the tires would, with proper alignment, likely last longer rather than shorter... ?

I also use polyurethane bushings in my Audi 80, just like mdonau.
I can confirm his experience: The driving behavior is noticeably better, although the comfort has deteriorated slightly.

Sure, Ulf! Subsequently, as mentioned by the parts manager, the wheel alignment will need to be adjusted.

Quote:

With full-camber settings, the fore-to-aft swing range would be significantly reduced, and based on my gut feeling, I would guess that the tires would last longer rather than shorter (with proper alignment) . . . ?

That cannot be generalized in this way.
The leverage/arm ratios of the control arms (or, to put it another way, what happens to the shock absorber when the rear mounting point pivots in or out) are the key factors here. Because the lower ball joint is located closer to the front control arm bushing (pivot point), when the rear bushing is angled, the ball joint primarily moves backward and slightly inward, which mainly results in increased toe-in.
Whether and how the alignment conditions change depends, among other things, on whether and at what distance (measured from the transverse axis of the vehicle) the steering linkage is located from the pivot points of the track rods (track rod end to strut).
That would be a good idea. It is possible that, depending on the design, the altered track width during the deflection of the rubber bushing may change the track direction positively, and this change is then compensated for by what is known as shortening the tie rod (arrangement of the steering linkage to the suspension).

Overall, I believe that a stricter interpretation of the regulations generally improves handling and drivability. However, it is questionable whether this ultimately provides an advantage when considering all driving characteristics (lack of inherent dynamics) and comfort.
Furthermore, it should be noted that road bumps are almost unfiltered and transmitted to the chassis and steering system, which does not necessarily improve their durability.

mdonau wrote:

-no load change issues. -No "kickback" from the suspension during the initial braking phase when performing emergency braking. -No vague steering feel around the center position.

*grumble*, why am I only finding this out now? Well, I can definitely confirm your "before" observations. I've always compensated for sudden drops in engine power by gently easing off the clutch, so that everything doesn't get thrown around inside the car.

I would attribute the main difference to the noise comfort; the A2, being a narrow and tall design, is generally quite stiff.
That may not be all, but for example, the "Naseloch-Passat" (32B?), according to the brochure, had a specifically designed, longitudinally flexible front axle, achieved through a soft bearing on the rear inner side of the control arm.

Hi,

The 32B is the angular model produced up to '87/'88, and it's technically similar to the...
Audis from that era (with longitudinal engine).

The 35i "nasenbiär" (literally "big nose bear") has the same front axle as the Golf 2+3, which offers similar handling characteristics.
The storage space is nowhere near as large as it is in the 9N and similar models.

In my opinion, tire wear is caused at least 80% by the transmission of...
As long as the track alignment isn't completely off, I consider the braking and propulsion power to be a negligible factor.

Best regards, Michael.

BM wrote:

Furthermore, it should be noted that road bumps are almost unfiltered and transmitted to the chassis and steering system, which does not necessarily improve their durability.

That is the description for full rubber (instead of the standard stepped) bushings, if I understand correctly.

And just one more question about that:
The rubber shims in the standard bearings only loosely center the rear control arm pivot. In the event of impacts, the rear end of the control arm is initially accelerated sharply to the right or left and then slams against the stop of the rubber bushing – which is somewhat soft, as the inner mounting bracket and the outer bushing shell are made of the same rubber part.
However, what always comes to mind is a heavy piece of luggage in the trunk that starts to slide during sudden acceleration, braking, or sharp turns, and then slams against the backrest, tailgate, or inner fender (we can even put a piece of carpet or something similar in between to cushion the impact of the rubber). If the load is properly secured, it cannot start moving, and no more jolts will be transmitted to the vehicle's body.
According to my opinion, the A2 full rubber bushing corresponds to the principle of securing a load, as the rubber bushing still has some elasticity and can filter out sudden forces acting on the control arm by giving way slightly – just as elastic luggage straps would dampen the force transmission to the body if, for example, someone bumped into the luggage.

Here's the translation:

In my theory, I don't necessarily see higher material stress due to road bumps, etc., when converting the Polo to A2 suspension.
What do you think about it?

Quote:

That is the description for full rubber (instead of the standard bridge-) bushings, if I understand correctly.

Sorry, no - this applies to polyurethane; with solid rubber, the same effect occurs, but likely in a less pronounced form.

Quote:

In my theory, retrofitting the Polo with A2 suspension components doesn't necessarily lead to higher stress on the materials due to road bumps, etc. What do you think about it?

You can't compare this to a loose piece of luggage rattling around in the trunk (Force = Mass x Acceleration). This effect will not have a significant impact on the control arm because the short travel distance to the stop prevents any substantial acceleration.

Ultimately, despite all the considerations, I would also opt for the solid rubber bearings. Perhaps they aren't as tough as they seem.