Vibration in Steering Wheel and Brakes

Hi!
Approximately 5,000 km ago, I replaced all the brake rotors and pads because the pads were worn and the rotors were also nearing the end of their lifespan. At that time, the steering wheel started to vibrate more and more when braking from around 130 km/h. After the replacement, everything was fine again, and there was no more vibration noticeable when braking.
Now, the whole mess is starting all over again. Recently, I lifted the car and slowly turned the wheels by hand and noticed a slight wobble on the rear left brake disc. Now I'm wondering where it's coming from again? The car is actually always in full use, which means that corrosion can't be the cause. Also, it started subtly and is now getting worse again.
Can the brake caliper or piston have a slight "tick" and repeatedly impart a "bump" to the brake disc ?
I somehow don't feel like having to replace the brake discs every few thousand kilometers. Besides, this vibration is extremely annoying .
Sure, here is the translation of the German text into English:

"Please provide me with tips or potential errors."
Sure, here is the translation of the text from German to English:

"MFG" is an abbreviation for "mit freundlichen Grüßen," which means "best regards" or "sincerely." It is commonly used in German-language emails and letters.

Perhaps the brake is dragging, causing it to overheat and then seize up.

Rear left, is the handbrake cable securely attached to the caliper? Are the guides and pads secure?

There are several causes for warped brake discs. One possibility is that residual stresses from the manufacturing process were present in the material of the disc, which were released at higher temperatures, causing the disc to warp (indicating poor quality). Alternatively, a hot disc can become warped if it cools down unevenly (locally), for example, due to splashed water from a puddle.

The problem can usually be solved by rotating the disc(s) (especially in the first case). However, the disc must still be thick enough for this to work; otherwise, the only solution is to replace it.

Edit: Just saw the previous response... you're right, of course. Definitely check the caliper for proper function.

Okay, here's the translation:

'Just to add, I'm a bit surprised that it's already noticeable in the steering, specifically in the HA (likely referring to a specific component or system).'

Sure.
If you feel it in the steering, it must be the front brake discs... hmm.

Is the entire system malfunctioning? Depending on the age, the brake hoses may be faulty. Or, a master cylinder might have clogged ports, preventing the brake pressure from fully releasing.
Recently, there was a thread discussing a situation where a faulty master cylinder was installed.

Saddle supports or fixed linings are also unlikely, because according to the post, the braking system was only recently replaced. Stuck handbrake linkage levers can only occur on the rear axle.

We need to know the vehicle type and the year it was manufactured.
And perhaps some information about which brake discs and pads were actually installed (for quality assessment ).

Here I am again!
The vehicle is an Audi A3, model year 1999, with engine code AHF.
So, I actually thought that the steering wheel vibration would be noticeable due to an impact on the front brake discs. However, I recently had the car on a lift (a Merzerl pushed me off the highway ), and during that time, I manually rotated each wheel. As I said, I only noticed a slightly uneven rotation on the rear brake disc. I also didn't think that it would have such an extreme effect on the steering. The brake cylinders have never been replaced, and I couldn't find any play in the tie rods or other parts of the front axle (including the wheel bearings).
I can actually also rule out water droplets on the hot glass, because the shaking has started again and is now getting worse .
Furthermore, the wheels turned easily, which allowed me to rule out a stuck piston or a dragging brake.
Regarding the quality, I must say that these are replica parts. Based on the price, they cannot be high-performance discs, but after the first test drive with the new ones, I actually had a good feeling. (also for about 5,000 km after installation ). Furthermore, the new ones grip better on wet roads than the original Audi parts .

Those are probably the rotors. I also had new rotors and pads installed on the front recently. They were from eBay (of course, original equipment quality ). It only took about a week, and they were already warped (but they still had very good braking performance). The old rotors ran smoothly until the very end. You probably have to buy from VW to avoid this kind of problem.

/Jan

I have perforated discs from Otto Zimmermann (you can easily find them by searching online).

Since then, my Superb has been braking really well, and it's no longer shaking.

'In the past, I used to replace brake discs and pads approximately every 15,000 to 20,000 miles.'

These ones already have 7,000 miles on them, and there's absolutely no sign of wear.

Other brake rotors do the same thing - I have Ate PowerDiscs on my Octavia (50,000 km) - and since then, the steering wheel vibration has also disappeared!!!

Oh yeah, and both cars have Ate brake pads.

The original manufacturer's brakes are junk for people who ride lightly and for older folks...


best regards, emil

Hi,

"I had the same problem with my 4 new (unvented) Zimmermann brake discs. Well, they were a few euros cheaper than the original parts. The other day, I got annoyed and just did a few full stops from 200 to 50 km/h (in an empty A3 at night). The problem with a TDI is that it's not easy to brake and accelerate at the same time, so you have to be very careful to find a stretch of road where no one is behind you."
Let it cool down slowly (or gradually), and since then, nothing has vibrated anymore.

Best regards, Rainer.

Hello,

Does that mean that the sudden braking removed the imbalance in the brake discs?

Best regards,

renwal

I might also try the process of grinding down 200. It could really work. If the discs heat up properly and the tensions within the disc are released, the runout should also disappear .
Furthermore, the shaking actually only occurs during light braking between 120 and 80 km/h. There is no shaking above or below that speed range. Let's see, I'll try it out today.

Quote:

If the glass heats up properly and the tensions within the glass dissipate, then the impact sound should also disappear icon_lol.gif

Yes, that's exactly how it works. It's essentially annealing in the installed state.

"In my opinion, these things are just too flimsy, and my next set of windshields will definitely be original ones."

Best regards, Rainer.

Hello,
I've encountered this problem with many vehicles. My observation is that the wheel hubs are often warped, which causes the brake disc to slowly adapt to the shape of the hub and become warped itself, or even more warped due to the larger diameter. You can replace the brake discs repeatedly, but the problem keeps recurring. When there are vibrations in the brake disc, the contact surface of the wheel hub should ideally be checked for absolute flatness using a dial gauge. Repair manuals provide tolerance values for this. It's also important to thoroughly clean the contact surface of the wheel hub, as even a small amount of dirt or rust can cause the brake disc to warp. Unfortunately, not everyone has a dial gauge to measure the runout, but the fact that the wheel hub might be warped should always be considered.
I think it's nonsense to buy brake discs that are advertised as 'original.' The choice of manufacturer is important. For example, I believe that brands like ATE, Jurid, or Textar actually produce parts that meet original equipment quality standards. However, I would avoid brands like Ferodo (sold at ATU) or any generic, unknown manufacturers.
Best regards, caro.

Oh, I forgot.
For example, wheel hubs can easily become warped if you drive just a few thousand kilometers with improperly tightened wheel bolts. If two wheel bolts are tightened to 100 Nm and two to 200 Nm, the hub, along with the brake disc, can become warped. If you arbitrarily tighten the bolts with a cheap wrench, this can happen very quickly.

Of course, the entire problem could also be caused by simply worn brake discs. However, if you want to claim the brake discs under warranty, a specialized workshop usually needs to check the flatness of the wheel hubs.

expensive

Hello,

Can the flatness of the wheel hubs be checked yourself or at a VAG dealer? My brake discs have already been replaced several times, and the imbalance always returns after a maximum of 5,000 km.

Best regards,

renwal

P.S. By the way, what is the labor cost for replacing a wheel hub?

Unfortunately, it is only possible to definitively determine whether the wheel hubs are flat or not when they are installed, using a dial gauge and a dial gauge holder. A specialized workshop should be able to do this.
'The cost of all this is a difficult question with Skoda. A front hub would likely cost around 120 euros. A front wheel bearing (which should also be replaced, as removing the hub puts a lot of stress on the wheel bearing) would be around 70 euros. Installation including replacing the wheel bearing is approximately 1.2 hours per side. Depending on the workshop's procedure, an alignment might also be necessary, which would cost around 70 euros.'

Best regards, caro.

I inquired with Porsche Interauto today, and they said that the measurement of the windows and hubcaps would cost around 60 euros. Any additional costs will depend on the results of the measurement.

Best regards,

renwal