Brake Pedal Seat Ibiza - Replacement & Repair

Hello everyone,

Is there a way to make the brake pedal feel more defined/firmer in my Ibiza?

Unfortunately, I have very little braking power (which is compensated for by my large quadriceps), and no noticeable pedal feel; the brake pedal is "soft." Pumping the brakes doesn't help, and the brake fluid was changed 5,000 km ago, with no noticeable loss since then.

Also, the brake pedal is stiff if the car has been standing for a few days.

Does anyone have any ideas?

The car is a Seat Ibiza 6L with a 96kw engine and Lucas brakes (288mm front, 232mm rear).

The brake pads are EBC Greenstuff, and the rotors are Nordmann (OEM). I wouldn't recommend this combination. When cold, the braking performance is similar to the original equipment. They improve slightly after a short warm-up period, but during a full stop from 160 km/h, they get so hot that they barely provide any braking force.

Best regards, Tom.

sik wrote:

Hello everyone, Is there a way to make the brake pedal feel more defined/firmer in my Ibiza? Unfortunately, I have very little braking power (which is compensated for by my large quadriceps), and no bite point at all; the brake pedal feels "soft." Pumping doesn't help, and the brake fluid was changed 5000 km ago, with no noticeable loss since then. Also, the brake pedal is stiff if the car has been standing for a few days.

Hi,

The brake point is primarily determined by the elasticity of the brake hoses, the elastic deformation of the brake calipers, and the brake pads.

The stiffness of the brake pedal may be due to a faulty check valve in the brake control unit (BCU). Depending on the mileage, new brake lines alone can significantly improve this "spongy" feeling.
Pumping only works if there is air in the system. Pumping a system that is not air-bound will likely reduce the effectiveness of the power brake assist, as each time you depress the pedal, you are venting the pressure side of the power brake system. How far does the pedal travel during a full brake application? There should still be about 1/3 of the pedal travel remaining.

"Green Stuff" is made of a fairly soft material, so that the pads themselves compress it like a sponge, even under high pressure.

It's hard to say how far I can push it, but it's more likely to be all the way down rather than in the middle of the pedal travel.

Unfortunately, I only have a Ford Focus 1 and a new Mégane for comparison, and there's a huge difference between them. Both of them start braking very firmly after about 1/4 of the braking distance, while in my car, it starts gradually around 2/3 of the way.

I'm really disappointed with the EBC brake pads; they're not really worth the money. Or maybe the combination [of components] is simply bad...

Hi,

Is the vacuum system sealed? Especially the thick hose to the brake master cylinder? This probably doesn't explain all the other problems (with a very leaky hose, my brakes still felt almost normal in terms of pedal feel), but it could be the reason why the pedal feels stiff after being idle for a while.

Best regards,

Jan.

Hi,
I'm going to check the vacuum system. Does anyone know where the BKV (boost control valve) is located on a 6L engine?

So, there's no way to adjust anything on the brakes?

Best regards, Tom.

sik wrote:

Hi, I'm going to check the vacuum system. Does anyone know where the BKV (boost control valve) is located on a 6L engine? So, there's no way to adjust anything on the brakes?

The vacuum system only relates to the stiffness of the pedal. If the brake feels too soft during operation, and if braking only begins when the pedal is pressed about two-thirds of the way down, then there is either air in the system (e.g., in the ABS), or there may be a defect in the hydraulic brake booster (HBZ).

How can I determine this? (Defect in the HBZ - likely referring to a specific device or component).

I'm ruling out air leaks because the blower fan was recently replaced (without any improvement).

Here's another piece of information: When the engine is running and I press the brake pedal firmly, it slowly sinks to the floor, taking approximately 10-15 seconds.

sik wrote:

How can I determine that? (Defect in the HBZ) I'm ruling out air leaks because the blower fan was recently replaced (without any improvement). Here's another note: If I press the pedal firmly while the engine is running, it slowly sinks to the floor, taking approximately 10-15 seconds.

"If everything seems tight (meaning nothing is leaking), I would say these signs indicate an internal leak in the heat exchanger. I can't tell you how to test for that specifically, but to be sure, I would disconnect the two pressure lines at the heat exchanger and create temporary plugs from old pipes. This would help isolate the heat exchanger and narrow down the problem without unnecessarily replacing parts. However, in my opinion, the symptoms point to the heat exchanger."

Okay, thank you very much for your help!

HBZ and BKV are located directly below the surge tank, so maybe I can even install them myself.

When I go to the workshop, they will laugh at me again and leave me with the comment, "You're already braking, what more do you want?"

Can you explain the thing about the blind plugs further? Are you saying I should disconnect the hydraulic brake booster (HBZ) from the brakes and then test it like that?

sik wrote:

I can rule out air, as the fuel pump was recently replaced (without any improvement).

The conclusion is not entirely correct. In some vehicles, the ABS bleed process must be performed using a diagnostic tool, for example, in A3 models with EDS.

I also suspect there's air in the system.

sik wrote:

How can I determine that? (Defect in the HBZ) I'm ruling out air leaks because the blower fan was recently replaced (without any improvement). Here's another note: If I press the pedal firmly while the engine is running, it slowly sinks to the floor, taking approximately 10-15 seconds.

Have you checked yet?
/viewtopic.php?t=11929&highlight=strange+brake

I had bled the brakes several times back then, but it didn't help, and now it's clear why.

Best regards, Rainer.

If it's not Rainer's specific issue, it could also be that the rear brakes are generally not providing enough stopping power. In that case, you would have to press the pedal harder to achieve the desired braking performance, which would naturally cause the pedal to sink further.
Furthermore, your system is not reliable, which also supports my point. My Greenstuff products, on the other hand, don't cause any problems.

Rainer K. wrote:

I had bled the brakes several times back then, but it didn't help, and now it's clear why. Greetings, Rainer

Hi,

Did that also result in a loss of brake fluid? I mean, if you pump the pedal 20 times while bleeding the brakes, you can say that the reservoir is pretty much empty.

If it's a known vulnerability, I would definitely start by checking there. Maybe try pressing the pedal all the way to the floor three times and see if you can spot any oil leaks.

A friend of mine once had a similar issue with the brake lines on a Passat and simply had them welded together. This would be at least the final step to check the tightness of the brake lines in the hydraulic brake booster, although even with a leak, you shouldn't feel any resistance until around 70% pedal travel.