Squeaking problem... brakes or something else?

Hello everyone,

"For about 8000 kilometers, I've been experiencing a sometimes quite annoying squeaking sound when braking, and occasionally also when driving slowly. We in this forum initially thought it might be small stones or something similar that had gotten lodged in the brake pads, causing the noise. The workshop suggested the same thing, adding that it would definitely disappear on its own as the pads wear down."

"Since then, 8000 km have passed, which is quite a distance. I also mentioned it during the inspection a month ago, and they took off the wheels (or at least, that's what they said) to examine the brake discs and pads. They said everything was fine, and there were no burrs or other imperfections that could cause this."

What's concerning me a bit is that it can occur in different degrees, and I'm not entirely sure if it's "just" the brakes. It's making a squealing noise:

- sometimes, when rolling slowly, it seems to depend on the wheel rotation; it changes the tone slightly during light braking and becomes silent during hard braking.

- front - when you engage the parking brake while moving slowly, it has no effect.

- Significantly stronger and more intense when reversing slowly, especially with the wheels turned (e.g., parking).

- It changes its tone when you accelerate more strongly from a slow roll, and this is, in my opinion, not just due to the faster rotation of the wheels.

- is hardly dependent on humidity; the squealing sound of wet brakes sounds different.

- but doesn't always occur and is difficult to classify.

- is independent of the selected gear and independent of whether the clutch is engaged or disengaged.

What do you think – could there be other causes besides the brakes? For example, the wheel bearings or the drivetrain?

"I want to, when the opportunity arises (which isn't easy in a big city), carefully remove each spoke one by one and, by rotating it, try to figure out exactly where it is, and maybe test other things as well. What specifically should I pay attention to while doing this, and what else should I try?"

The wheel bearings probably feel "tight," at least if you press down on the top of the wheel with your foot while the car is parked; there shouldn't be any play or wobble.

The car now has 16,700 kilometers on the odometer, and it has four disc brakes.

Best regards,

Jan.

Hello Jan,

My guess: the front brake pads are sticking in their guides, which causes them to constantly rub against the rotors. I can verschandeln the guides of the brake pads on the caliper with a small file/remove any rust without damaging the rubber boots of the pistons .
Then apply a homeopathic dose of copper-containing assembly paste to the contact surfaces of the brake pads on the guides; that should fix it as long as the car is running.
While you're at it, could you check that rubber boot? You don't want any animals to have chewed on it, which could then cause the brake pistons to seize due to rust.

Best regards, Rainer.

Hi Rainer,

I used to think something similar back then, and I'll probably check that out or do it myself soon.

But wouldn't it gradually wear away over the course of 8,000 kilometers?

Or is it expressing itself through heat? I've repeatedly touched the brake pad holders after longer drives, and there was no sign of abnormally high temperatures – although the warming could be so gradual that the airflow dissipates it.

So, would you also rule out wheel bearings or drive components?

Best regards,

Jan.

Hello Jan,

Jan6K wrote:

Aber muesste sich das in dem Fall nicht im Laufe von 8000 km irgendwie wegschleifen?

Unfortunately not, the brake pads are stuck in their guides, and every time you brake, you'll experience that grinding problem again.

Quote:

Or does it express itself through heat? I have repeatedly touched the brake pad holders after longer drives, and there was no sign of abnormally high temperatures - although the heating could be so gradual that the airflow dissipates it.

As you mentioned, if it's only lightly scraping, it won't get excessively hot. However, the brake disc will still wear down much faster, so you shouldn't wait too long to check it.

Quote:

Radlager oder Antriebe wuerdest du also auch ausschliessen?

As I said, I can't be sure, but this is just my idea, and it's the one I think is most likely.

Regards, Rainer.



Best regards,

Jan[/quote].

Hi Rainer,

That makes sense regarding the guides. I'll try to take care of that as soon as possible, because I don't want to unnecessarily grind down the glass.

Best regards,

Jan.

Hi! I noticed a similar problem yesterday during the oil change, when both front wheels were off the ground.

You can feel significant resistance when turning a front wheel by hand, and you hear a metallic grinding noise. (Transmission in neutral).

Sure, some of the resistance is due to friction points in the drivetrain (e.g., constant velocity joints, shaft seals, bearings, gears). But the metallic noise clearly comes from the brake discs.

When turning the right front wheel, the left front wheel rotates along with it, but with some slippage. Conversely, when turning the left front wheel, the right front wheel remains stationary. Since a differential is perfectly symmetrical, the only explanation that fits is a variation in the frictional resistance.

Is this a design flaw, or could assembly errors or defective replacement parts be the cause? (The brake pads and rotors were replaced about 40,000 km ago at ATU).

I find it hard to imagine that this was intentionally designed, especially considering today's fuel-efficient cars. Furthermore, it also reduces the lifespan of the wheel brakes.

However, I am experiencing an absolutely acceptable level of fuel consumption, which is also within the manufacturer's specifications. When driving slowly in neutral, there is no noticeable resistance.

I also noticed squealing brakes on my father's Volkswagen Golf II.

'Hey Rainer, I'm planning to try out your tips next time when I change my tires. Could you elaborate a bit more on them? Do you really mean that nothing needs to be disassembled? Right now, all I have available is cleaning spray.'

Regards,
Holger.

HI,

I started that thread over two years ago... and at the time, I couldn't really look into it further because I didn't have the time, then the weather was bad, and when both of those things improved, I stopped hearing the noise. It hasn't come back since, and it seems the brakes haven't suffered from it either, because I'm still using the original brake discs and pads with over 53,000 km on them, a significant portion of which was driven in city traffic in Berlin, where you often have to use the brakes quite heavily.

Regarding the rotational resistance of the wheels when fully locked, I was also shocked back then by how difficult it was with the TDI compared to smaller gasoline engines.

Regarding the asymmetry you're seeing... could one of the drive shafts be possibly stuck or resting somewhere in a raised and lowered position? I remember that being the case with Trabants, where it only affected the longer right-hand shaft.

Best regards,

Jan.

Hi Jan,

No, I didn't notice that the constant velocity joints were worn anywhere. There was also no noticeable difference in the grinding resistance felt. So, the difference seems to be minimal.

Regarding the rotational resistance of the wheels when fully locked, I was also shocked back then by how difficult it is with the TDI compared to smaller gasoline engines.

Hmm... This grinding issue seems to have less to do with the engine concept itself, doesn't it? As I said, my father's Golf II had the same problem (a 55 horsepower gasoline engine).
Sure, with more powerful engines and heavier vehicles, everything is a bit stronger, and therefore also harder to turn by hand.

Speaking of Trabis: On my Trabant, both front wheels and their drum brakes were always very loose.

Do you also hear that grinding noise from the brake discs when you turn the wheels by hand?

Best regards,

Hi,

If you want to seriously check the front brakes, you must use only the handbrake to slow the car down for the last bit before parking. The pistons in the disc brakes are retracted by the slight movement of the rotor, which is why they almost always make a grinding noise when you turn them by hand.

Hi,

Quote:

Do you also hear that grinding noise from the brake discs when you turn the wheels by hand?

No... at least, I don't remember it.

With my Trabant, it was also the case that you could easily turn the wheels.

My reference point for gasoline engines was a 45 horsepower Polo with a gearbox that probably has to withstand less than 100 Nm of torque. That's likely quite a difference.

Best regards,

Jan.