Rear brake hot after replacement

Hello everyone,

"This weekend, there was a recall campaign for my Golf IV where new brake hoses had to be installed on the rear brake calipers (due to a leaky hollow bolt caused by corrosion)."
And in the process, I also threw out the old rotors and brake pads.

Then I assembled it (having previously retracted the brake piston using a special tool) - I had already done this several times on this car before.

This time, however, it was necessary to bleed the system (due to the new hoses). I did that manually using pumps, but it wasn't 100% perfect, so I had it bled at the workshop.

To my disappointment, after the first 15 minutes of driving, I noticed that the rear brakes were getting very hot. The reason seems to be that the calipers are not 100% free-moving when the handbrake is loose. Fortunately, nothing overheated, and the distance was short. The wheels are hardly braking at all.


What did I do wrong?

When assembling, it is recommended to readjust the handbrake. Now I'm wondering if you should first use the foot brake to "position" the pads – that is, to bring them into contact with the disc – or if you should engage the handbrake first before applying the foot brake.

The handbrake levers are touching the stops when the handbrake is released, and they also move when the brake is engaged. Therefore, I can rule out problems related to fixed handbrake positions.

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When the parking brake is released, the handbrake levers are against their stops and move even when the brake is engaged. Therefore, I can rule out problems related to fixed handbrake adjustments.

The levers must be positioned approximately 1-2 mm away from the stop when the handbrake is released.
This is to give the wooden blocks more room to expand when they "swell."

Suggestion: Push the pistons back, perform the initial adjustment (as described), check the handbrake/handbrake cable. Verify the free movement of the pistons by manually moving the handbrake lever on the caliper. When releasing, the piston should visibly retract by a minimum of approximately 1-2/10 mm. This is achieved by the reseating of the sealing ring. If this does not happen, the piston is seized. The caliper mounting brackets must be cleaned of any rust and lubricated so that the brake pads can move freely and remain free. The same applies to the guide pins.
If everything is okay, assemble and test.

Okay, I will do that.
Does it make a difference when installing brakes whether I pull and adjust the handbrake first before pressing the brake pads against the disc with the foot brake, or vice versa?

Holger247 wrote:

Okay, I will do it that way. Does it make a difference when installing

whether I pull and adjust the handbrake first before pressing the brake pads against the disc with the foot brake, or vice versa?

It is important that the initial adjustment is made before the pads are mounted, i.e., before the pads come into contact with the rotor.
Whether the actual wedging of the blocks is achieved by repeatedly engaging the handbrake or by using the foot brake is not relevant in this case.

Quote:

GIV - 98

The rear brake tends to seize, just like on the A3 8L. There are two different brake caliper variants, and I had the one that always seizes. I think it was the variant made of aluminum instead of cast iron. Please correct me if I'm mistaken.

Whatever BM writes is definitely worth considering, but it won't help much in the medium term if you've installed the "Looser" version.

Best regards, Rainer.

Hi,
I thought that with the rear brakes that have automatic adjustment, after retracting the pistons, the foot brake must first be applied so that the pads make contact and the adjustment mechanism can properly adjust . Then, the initial setting is checked. According to the RLF (presumably a reference manual or document), and it works that way for me too.
hg
Herbert.

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What BM writes is definitely worth considering, but it won't help much in the medium term if you've installed the Looser version.

It's likely that corrosion has formed on the brake caliper, specifically on the bridge between the sealing ring and the dust boot. This corrosion causes the piston to seize or prevents it from returning to its original position due to the deformation/tension of the sealing ring. This could cause the handbrake to adjust itself further than it should.
For someone who knows what they're doing, this can be easily fixed with some time and possibly a replacement part (such as a seal or gasket). To do this, the piston needs to be completely pushed out of its housing. The prerequisite is a functioning parking brake mechanism within the caliper.

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Hi, I thought that with the rear brakes that have automatic adjustment, after retracting the pistons, the foot brake must be applied first so that the pads make contact and the adjustment mechanism can set itself correctly.

The brake piston is acted upon by a spindle with a relatively steep thread on the handbrake side. Inside the piston is a threaded nut. This nut is only rotationally fixed when the spindle is under pressure (when the handbrake is engaged). Therefore, when the retracted piston is actuated by the foot brake (depressed), the nut unwinds on the spindle's thread until it comes into contact with a type of spring element inside the piston. This spring element is intended to ensure the necessary clearance (but is sometimes not sufficient). The same applies when the brake is "engaged" via the handbrake lever. This is the basic principle of the self-adjustment mechanism. Therefore, it is also very important that the pistons are 100% free-moving, and that the handbrake levers are not fully engaged, so that there is still some reserve travel available on the levers in case the brake pads swell, as the pre-tensioned levers do not represent a rigid obstacle compared to the stop.

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Then, the basic settings will be checked. According to the RLF, at least, and it works that way for me too.

If the brake pads are already contacting and, during the initial adjustment check, it is determined that the levers are hitting the stop of the caliper, the handbrake cables need to be tightened further. This will cause the brakes to rub. Therefore, in this case, adjust the handbrake cables accordingly first.
With a drum brake, it works exactly the opposite way.

BM wrote:

It's likely that corrosion has formed on the brake caliper, specifically on the bridge between the sealing ring and the dust boot. This corrosion causes the piston to seize or prevents it from returning to its original position due to the deformation/tension of the sealing ring. As a result, the handbrake

may adjust itself further than it should.

Hello,

I'm afraid I have to confirm...

On Saturday, I replaced the rear brake pads and dust shields on my 1998 A3. The right rear caliper retracted well, but it was a bit stiffer than usual. That was enough for now...

Due to the fact that every year after winter it was necessary to lubricate the caliper pistons (dust boots were in good condition), and because the right caliper, specifically the area where the brake pads sit, was so corroded that the pads were no longer properly aligned, the calipers were replaced today with AT calipers.

"I would be satisfied if the aluminum parts last another 12 years and 195,000 km."

To ensure that my contribution wasn't entirely in vain, I'm re-posting the message that Herbert had previously deleted. This is to illustrate that there are indeed differences in the procedure depending on the specific vehicle.

Code:

Herbert KFZ-Schrauber seit: 22.06.2005 Beiträge: 552 Karma: +6 / -0 ApplausBuh     Neuer Beitrag14-04-2011, 22:34    Hi, Zitat: Wenn die Bremsklötze schon anliegen und sich bei der Überprüfung der Grundeinstellung herausstellt, daß die Hebel am Anschlag des Sattels anliegen, müssen die Handbremsseile mehr vorgespannt werden, was dann zum schleifen der Bremse führt. Deshalb zuerst in dem Fall die Handbremsseile entsprechend einstellen. Sehe ich genau anders - wenn die Hebel bei eingebremster Fußbremse anliegen, muß die Seilspannung gelöst werden, bis sich die Hebel leicht alternierend bewegen lassen. Ich nehme an, das ist nicht nur bei meinem Audi 80 so. hg Herbert Audi 80 Avant B4 1Z 360Tkm (Passat Variant 32B CY 400Tkm)

Code:

‒ Fußbremse mindestens dreimal kräftig betätigen.      ‒ Handbremse 3-mal fest anziehen und anschließend wieder lösen. ‒ → Handbremshebel in Ruhestellung. Nachstellmutter soweit anziehen, bis sich die Hebel -Pfeil- an den Bremssätteln vom Anschlag abheben. ‒ Der Abstand zum Anschlag -Pfeil- an dem linken und rechten Bremssattel darf zusammen 1mm nicht unterschreiten bzw. 3mm nicht überschreiten. ‒ Prüfen, ob beide Räder frei durchdrehen. Nach der Neueinstellung ist durch die automatische Nachstellung der Hinterradbremse ein Nachstellen der Handbremse nicht mehr erforderlich.

I see it completely differently - if the levers touch when the foot brake is applied, the cable tension must be loosened until the levers can move freely and alternately. I assume this isn't just the case with my Audi 80.

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You are right about the Audi 80. The levers must rest against what is called the "stop" (which isn't really a stop). For the Golf IV or Passat, it's different. The RLF states the following:

Hi,

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If the brake pads are already touching and, during the initial adjustment check, it is determined that the levers are hitting the stop of the caliper, the handbrake cables must be tightened further, which will then cause the brakes to rub.

Perhaps we are talking about different brake calipers. For the Audi 80 B4, after replacing the brake pads, the foot brake should be applied several times. This pushes the pistons and pads into the working position, and activates the spindle mechanism you described, thus also adjusting the handbrake. After the initial adjustment, when the parking brake is released, the brake levers should be flush with the stop on the caliper and should not move against each other.
When the levers move against each other, i.e., The parking brake is too tight, causing the car to have excessive tension.
hg
Herbert.

Oh, why are you deleting your comment? It wasn't necessary. Your statement is 100% accurate when it comes to the Audi 80. Therefore, I took the time to bring your post back from obscurity .

Hi,
I had a suspicion – you don't write things randomly, after all. That's why I checked my point again and wrote a new post. The solution I provided (in my first post) was incorrect for the B4 problem.
hg
Herbert.

Hello everyone,

First of all, thank you very much for all the helpful answers.

I reviewed everything again over the weekend.

1. Handbrake game disabled (but that was probably not the actual problem).
2. Moved the brake caliper pistons again.
As B.M. already mentioned, the ventilation of the disc is achieved by the return movement of the brake piston, which is facilitated by the seal.
The piston was simply not moving smoothly enough.
With the new pistons and pads, the piston is now operating at a different working point. There were "deposits" and some light rust on the piston.
I looked at these on a website after I removed the piston.

Of course, the piston could have been disassembled, cleaned, and resealed (especially since the handbrake levers are still functional).

But I was hesitant to do all that work, because you never know if they'll have a different problem next year, and I might have to start all over again.

So, I ended up being generous after all and bought two new brake calipers, and now everything is perfect.

Okay, thank you all again.

Regards,

Holgi247

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But I was then hesitant to do all the work, because you don't know if they will have a different problem next year, and I might have to deal with the whole thing again.

He who dares wins.
The rust marks (as mentioned before) come from the cylinder located on the bridge between the dust seal and the oil seal. Removing both is actually a matter of just a few minutes. Whether it's new or not, something new is naturally better – but most of the time, it's unnecessary.