Brake Squeal: Causes and Solutions

Hi.

It's about my Golf 5 BLS, manufactured in August 2008, with 123,000 km on the odometer.
At 117,000 km, the brakes were completely replaced (discs and pads).
At 106,000 km, the front brake pads were replaced.

There's a kind of rubbing sound when I brake.

However, I'm not sure if it's a typical windshield crack, but I have the following suspicion:

There's a vacuum leak somewhere.
You need a lot of vacuum pressure when braking.
It always has to be newly generated, so you can hear the vacuum pump working to maintain the pressure.

Is that possible?
"There's no rubbing at the rear, because if there were, the handbrake would also be rubbing, right?"

"Does anyone have any suggestions for things I could test before investing a lot of money, only to have the warranty insurance company later say, "that's a wear and tear item"?"

m;

Hi,

Is there a connection to the switch to summer time?


Bzgl. Vacuum:

How many times can you pump the brake pedal while the engine is running until it becomes hard?
And what about when the engine is not running?

Compare that to the Passat.

No, summer and winter make no difference.

Since I hardly drive the car, I don't have much to compare it to.

Pumping is a good idea.
Yesterday, after about 2 hours of use, the pedal became hard, meaning the vacuum pressure was lost.

But the Passat sometimes does that too.

Generally, the differences between the two cars quickly become apparent again, such as:
Golf - pneumatic brake booster.
Passat - electric motor.

I've already tried giving it gas while braking, meaning increasing the vacuum pump frequency. But for the feeling, I need to brake with my right foot... and then it becomes complicated to give it gas.

m;

It's not a Toyota... when braking, a VW stops responding to the accelerator pedal... for about 1-2 seconds.
"In my case, the brake hydraulic line leading to the master cylinder had a tiny crack on the back. As a result, the brake pedal felt hard after a relatively short time. However, there was never any pulsating when braking. I also find that unlikely. I suspect slightly warped brake discs instead. If you gently press the brake pedal while rolling and observe it, then gradually release the brakes, you can feel on my Golf that the brake discs have areas where they grip better, meaning they are warped somewhere. A "smooth" roll-out is not possible; there's a slight "jerking" sensation."

Your description fits quite well.

I even considered whether the ESP's longitudinal acceleration sensor might indicate this in the log... I need to ask Shannon about that.

Otherwise, perhaps you could jack it up from the front and turn it around...?

m;

Or, for those who like to tinker:

Apply a generous amount of a strong cleaning agent (like wheel cleaner??) to the brake discs and let it sit. Once they are wet, push the car forward; you shouldn't see any contact points from the brake pads yet. You may need to apply the brakes very lightly for just one rotation .

Otherwise, expand it and put a ruler on it; it doesn't take long. I suspect it's warping, which isn't uncommon, and if, like in my case, the original discs are still at the front (although now they've been replaced, at 161,000 km), then they might simply be worn out .

Do you notice any steering wheel wobble when braking or when lightly applying the brakes at low speeds? This could indicate that the rotor is not properly seated on the hub.
Or is the noise more of a rumbling sound when braking from high speeds? I've experienced that before - it was a faulty wheel bearing in the front (which wasn't noticeable when cornering).
best regards
Herbert.

'Recently, just like Martin described, I've been experiencing a very annoying vibration when braking. The steering wheel also wobbled slightly. I was worried that this vibration would eventually damage my steering rack in the front axle. So, I immediately replaced the brake discs and pads – and now everything is quiet.'

What bothers me is that I don't know where the brake disc sustained the damage. I always drive quite gently and take care of the materials. Of course, I sometimes brake from over 200 km/h, but the disc should be able to handle that. It's internally ventilated and was an original Audi part, with approximately 30,000 km on it.

Regards,
Arne.

Quote:

What bothers me is that I don't know where the brake disc sustained the damage.

I would almost say it's rust. During the harsh winters, I often observed that the brake pads would stick to the rotors overnight. This creates a ring of rust around the pad. If this rust isn't immediately removed, more and more rust rings and pores develop over time, leading to different friction coefficients depending on the circumference of the brake disc.
This phenomenon is more pronounced and frequently observed in individuals with low braking force.

That might work, as I don't use the brakes very much... but in my case, it wasn't a big deal, because the rotors and pads had 160,000 km on them and were already old.

'Interesting theory - I've never heard anything like it before. But if that were true, then a lot of cars would be affected. My car was driven daily in the winter, about 100-150 km.'

Regards,
Arne.

So, in my case, it was only minimal and most noticeable with minimal brake pressure and speeds >= 50 km/h... and my car is driven daily for exactly 57 km .

Okay, now I understand exactly what you mean. If you lightly press the brake pedal, you get a pulsating feeling. This could actually be caused by the rust ring that is visible on the brake discs. At least, until you apply a stronger braking force. I used to experience this frequently with my TT. After 2-3 hard braking maneuvers from 120-0 km/h, it would usually disappear.

This time, after 2-3 seconds of braking, strong vibrations occurred – and the more forcefully you braked, the worse it got. This clearly indicates warping of the brake disc due to heat during braking. I jokingly mounted the discs on a balancing machine and observed and felt them, but there was nothing visible. You wouldn't be able to see such a slight imbalance.

Greetings.

Most often, the cause of the pulsating sensation is simply rust on the underside of the tire or around the rim, especially if a tire change has recently been performed.
If the rims are still in good condition in terms of their thickness, I remove them, clean the surfaces where the rims were attached, and remove any loose, flaking rust around the edges using the back of a hammer and a sanding disc.
hg
Herbert.

Oops.

We were driving a Golf on the highway yesterday.
The vibration is now quite uncomfortable (or, to be more precise, at high speeds).

I'm going to try removing the panels and cleaning the mounting surfaces.

What are the names of the 16" brake system for the Passat and the 15" brake system for the Golf?

m;

Okay,

Large cut.

Please provide the text you would like me to translate from German to English. I will then provide the translation without any explanations.

I opened the right side because I could hear a slight grinding noise that varied with the rotation.
- I cleaned a lot (especially the plant areas, including the hub and disc).
- Already believed in success during the filming process.
- Brakes applied from 140 km/h... nothing, just a rubbing sound.

Since the disc is about 19.4 mm thick (new ones are 22 mm, with a limit of 19 mm), I'm not even going to bother trying to fit it on the left side anymore; I'll just get new discs.

Now the question:

At 106,000 km, the front brake pads were replaced.
(rear components all new at 177,000 km)
Currently at 126,000 km.

Just the pads or should I replace the rotors as well?

m;