Rear brakes not engaging properly on VW Golf G4

Hi everyone,

On the rear right side of the G4 AXR limousine (manufactured in December 2001), the brake does not seem to be working correctly. The pads are almost worn down (only 2-3mm remaining) and they squeal when driving. On the left side, everything still looks good (over 6mm).
It seems like the brakes are not releasing properly after being applied. After driving, the brake disc is hot, and the aluminum rim also becomes noticeably warm.

I've read a bit about similar problems with the G3, but I haven't found anything about the G4.
Since I'm already planning to have my winter tires mounted this weekend, I might as well replace the brake pads and rotors at the same time. Changing brake discs and pads isn't really new territory for me, although so far I've only done it on the front axle.
Therefore, I have a few questions that I would prefer to have answered before I get too involved in this matter.

'What causes a brake to seize like that, and what can be done about it? It would be annoying if the new pads and rotor wore out again after such a short time.'

Is lubricating the guide, as described for the G3, also beneficial for the G4? Or could it cause other problems, such as with the ABS sensor?

'For the G4 caliper, as with almost all other brake calipers, you need to rotate and press the piston simultaneously to retract it, right?'

'Is a specific torque value required when tightening the brake caliper bolts?'

Is there perhaps still some kind of trap or peculiarity that one should be aware of?

It would be great if someone could share their experiences about it.

Thank you and best regards.

Eike.

Okay, maybe I can check off a few things on my list now.

The rear brake is the same as the one on the Passat. I haven't encountered any problems with Golfs in this area yet, but it's a common issue with older Passats. The handbrake mechanism often seizes up. This can be checked quickly: disconnect the brake cable and try to move the lever with force. It should move relatively easily. Lubrication usually doesn't help much in these cases.
Fixed pistons are quite rare. However, there are repair kits available if this is the case. You would need to remove the piston, install a new bellows and seals, and that should fix it. But in 98% of cases, this isn't your problem.

Unfortunately, I've never completely disassembled a brake caliper before. If you remove the piston and check the entire adjustment mechanism for smooth operation, you will probably find that it's sticking. This can be fixed, but it requires appropriate tools because a retaining ring at the bottom, behind the piston, needs to be removed. I don't have those tools, so I usually take calipers like this to a friend who works on repairs; it costs around 30€ from him, probably 60€ normally.

A used saddle as a replacement part is available for around €100.

It's better to have it professionally installed and expanded than to do it myself. It's quite safety-critical after all.

Okay, let's answer the questions now, after all that talk.

Yes, you need to rotate and press while retracting. Clamps and adjustable wrenches are generally sufficient for this. Saddles should be mounted with new securing screws, and the contact surface should be clean. Torque specifications are unknown; I would need to look them up. I wouldn't use grease; at most, heat-resistant silicone. No copper paste due to the ABS.
Otherwise, there are no other issues. The rear window panes actually always come off without any problems; it's nothing like the front ones.

Sure, here's the translation:

"Here are some points where I have ideas:"
1) The problem could be caused by the piston itself, for example due to a damaged seal, the handbrake lever, the guide on the caliper, or, more likely (as was the case with my G3 from 1993 and my A3 from 2000), the brake pads are stuck. When removing them, check if the pads are seized (they should slide easily). If they are, you've found the culprit.
Prevention:
- verschandeln the guide rails with a brake file until they have a smooth, even sheen, and then apply grease.
- If it turns out to be the pistons, replace the sealing rings and verschandeln them. Installation isn't entirely straightforward, but there are instructions available online.
- The handbrake lever (on the saddle itself) was already improved in the G3, but my 1993 G3 still suffers from it. Disassemble, clean, and lubricate. This is unlikely to be an issue with the G4, but it's worth checking.
- Check the brake caliper mounting bracket; if necessary, disassemble and lubricate it.
I can't think of anything else to say.
2) Yes, that's a good idea. I don't see copper grease as being overly problematic, because there's definitely a special type of grease available that is heat-resistant and also shouldn't cause any issues with the ABS system. I think it's some kind of ceramic compound (available in accessory shops).
3) Yes, the return mechanism is the easiest. This is how it works for all VAG vehicles with a handbrake integrated into the piston, at least as far as I know.
4) Should. I am not familiar with this and have never paid attention to it. Usually, the screws are included with the pads and have thread locker on them.
5) As far as I know, this is already covered under point 1.

eike wrote:

5. Is there perhaps still some kind of trap or peculiarity that one should be aware of?

My tip:

If everything is working again, try engaging the handbrake more frequently while driving, especially when there's no immediate danger (e.g., when rolling to a stop in front of a traffic light, without another car closely following behind).
Because regularly used mechanics generally break down less often than unused ones .

In addition to Ulf's suggestion:

If it's due to the brake pads. Every winter, you should briefly remove the brake calipers (just the rear ones). Then you can verschandeln the friction surfaces and apply new grease. Since you're reusing the same brake pads, you don't need to retract the pistons. You just need a little threadlocker. This not only prevents brake pads from sticking, but also ensures that they always make even contact. Often, you see vehicles where the rotor is only "clean" in some areas and rusty in others, which is usually where the brake pad makes contact.

If it was due to the handbrake lever, there are even some models that have a grease nipple integrated, which allows you to pump grease through and push the dirt out. It might be a bit cumbersome...

...Often you see vehicles where the windshield is only partially 'clean,' and in other areas there's rust, typically where the coating would normally be applied...

Hello,

First of all, thank you for the hints and answers. The discs indeed look as described above. Is this already an indication of stuck pads? I need to take a look at how the inner lining looks and whether it has also become as thin as the outer one.

What I don't quite understand at the moment is the reason why copper paste affects ABS function. Am I mistaken in thinking that it's only applied thinly to the contact surfaces between the brake caliper and the pad carrier to prevent them from rusting together?

I had instructed my partner to regularly use the handbrake (always engage it when parked) so that it wouldn't seize up. Surely that should be enough, right?
Okay, I won't be disassembling the seat myself. I'll leave that to a professional, especially since my wife probably wouldn't go for it; after all, it's 'her' car.


Greetings.

Eike.

eike wrote:

What I don't quite understand at the moment is the reason why copper paste affects ABS function. Am I wrong in thinking that it's only applied thinly to the contact surfaces between the brake caliper and the pad carrier to prevent them from rusting together?

Normally, a little bit of rust doesn't cause any problems. The grease is just there to prevent squeaking between the cover and the saddle, at least that's what I understand.

By the way, I'm also getting a little bit of grease on the track from the coating (near the saddle support).

I don't see the problem with ABS as being that severe. Some people use a lot of grease and aren't very careful when applying it. If the paste then gets onto the sensor or the ring, it probably impairs its function. I don't know why myself; I only heard about it from others, and yet I still use it if there's nothing else available. It's strange because copper isn't actually magnetic...

I also experienced this constantly with my G4. Cleaning and greasing didn't help. I then suspected the handbrake and, as a test, installed the return springs from a Passat. Unfortunately, this also didn't improve things. So, I installed a new brake caliper (about 150 euros from ). Since then, it has been quiet, but unfortunately, I haven't had time to disassemble the old one to take a look.

P.S. In a Passat manufactured in 04/2004, this problem occurred as early as 01/2006. However, in this case, the issue was caused by stiff brake pad guides.

Hi there,

I have now solved the problem by replacing the pads and rotors. Everything was corroded. One of the pads was even so rusted that it had detached from its carrier .
If you're interested, I can create a document with pictures so everyone knows what to expect and how it's done. By the way, it's advisable to use a special tool to push and turn the piston back into place at the same time. With a wrench, you simply don't have enough force (at least, I don't).

Greetings.

Eike.

Oops... honestly, the rotation hasn't been problematic at all with any of the brakes I've seen so far. It's clear that it's not the most elegant method. But if you only do it a maximum of 3 times a year, then it should be okay. If the piston was that difficult to move, there might be other problems. Check in about a week to see if the rotor is wearing evenly.

Detachable pads seem to be a more frequent issue with the 1J platform. With yours, I'm now aware of 5 cases. I assume these were the original pads...

@Eike
"Did you also make sure the brake track on the frame is perfectly 'clean'? It should be 100% smooth. I once just cleaned it, but due to 'edges' forming on the brake track, the pads still got stuck. Since then, I've been using a file and filing until the brake track has a uniform shine. I recommend that you repeat the cleaning process when the pads are down to about half their thickness; this will help them last longer."

Were the handbrake lever, saddle, and saddle guide moving freely?

matthiasTDI96 wrote:

Oops... well, to be honest, the rotation has been completely problem-free with all the brakes I've seen so far.

"Not with my G3; I would need a retraction tool for that, even though the brake caliper is refurbished."

@Eike
Did you also make sure the rails on the saddle carrier are perfectly 'smooth'? They should be 100% smooth.
Were the handbrake lever, saddle, and saddle guide moving freely?

Oops... well, to be honest, the rotation has been completely problem-free with all the brakes I've seen so far.

For my G3, it's not the same; I would definitely need a retraction mechanism, even with a rebuilt brake caliper...


Hi there,

I have filed all the surfaces because there was a thin layer of rust even underneath the small stainless steel sheets. Afterwards, I applied a thin layer of copper paste to the surfaces.
Afterwards, everything was working smoothly again.
I had borrowed the tool from a master craftsman who showed me how to use it while I was working on a Bora that was already on stage. He mentioned that it almost always required using this tool because it was difficult to turn.
It's important to spray the dust cover bellows on the piston with WD40 or a similar product beforehand, so that it doesn't rotate along with the piston and tear.

Greetings.

Eike.

eike wrote:

It is also important to spray the dust cover rubber bellows on the piston with WD40 or a similar product beforehand, so that it does not rotate along with the piston and tear.

Good idea, but be careful:

Many rubber seals will slowly swell when they come into contact with products based on mineral oil. This means the seals no longer provide a proper seal, and you end up in a situation that's just as problematic as if there were a tear.

As a non-critical lubricant, I am only familiar with silicone spray.

Does WD-40 make rubber brittle because it is a mineral oil?

I would recommend using technical petroleum jelly. It's more rubber-friendly.