Handbrake sticking which lead to brakes knocking

[DallySingh]

Hi all,

Have had a bit of a weird issue lately with my GT4. My handbrake has seized 4-5 times in the last of couple of weeks. I can clearly hear the mechanism disengage but it doesn't seem like the handbrake itself has turned off. I need to apply a fair bit of pressure to the accelerator to get the car moving when this happens.

One of the times it threw up an error on the dashboard but turning the car on and off got rid of it.

Two days ago, the handbrake seized up again. But this time I had to apply a lot more pressure to the accelerator to get it moving and when it did move, there was a loud "clunk" sound. I drove around for a bit and noticed that every time I would brake, there was a loud knocking sound coming from the front of the car.

Took it to Porsche yesterday which is about a 30min drive from mine but by the time I arrived there, the sound had gone (thankfully, I recorded it). The Porsche technician had a look and said there's visibly nothing wrong and the problem could be caused by a few factors:

• Not driving the car frequently enough (I've owned it since March and have only clocked 650miles so far).
• Getting the car washed and not driving it as it causes water to sit on drum brakes for the handbrake. - I did get the car washed last Friday and didn't drive it for 4 days.
• Due to the infrequent driving, the technician said the brakes haven't properly baked making them a lot sticker. He said they encounter this with most new cars that haven't been driven and when loading them off lorries.

I'm also a bit confused as the technician told me the handbrake uses drum brakes and not the discs and calipers which makes sense but why that knocking noise occur when using the foot brake?

I've been told it's nothing to worry about but I thought I'd ask in here to see whether anyone else has encountered this?

Here's a video of the knocking sound. You need to listen quite carefully as the engine is loud but you can hear a knocking sound as I approach the lights and start braking.

https://streamable.com/t4xdru

[Discombobulate]

My guess is that it's not the handbrake drum, but the pads binding to the discs when parked up. Common issue and explains noise on braking - you have residue stuck to the discs. Is there any vibration when braking at speed.
BTW, this is a known GT4 issue.

[DallySingh]

Discombobulate said:

My guess is that it's not the handbrake drum, but the pads binding to the discs when parked up. Common issue and explains noise on braking - you have residue stuck to the discs. Is there any vibration when braking at speed.
BTW, this is a known GT4 issue.

This makes sense as the knocking sound was only occurring when applying pressure to the footbrake. I imagine my drive to the Porsche garage sorted it as the problem didn't exist once I got there.

I wouldn't say there's any vibration when braking at speed but difficult to tell with the car itself being so loud.

Is this anything to be concerned about?

[bennno]

Dont apply the handbrake it its to be left parked for a few days or after washing.

I dont apply it to any of the cars we have in the garage, assuming its manual just put the car in first gear or reverse.

[DallySingh]

bennno said:

Dont apply the handbrake it its to be left parked for a few days or after washing.

I dont apply it to any of the cars we have in the garage, assuming its manual just put the car in first gear or reverse.

I've toyed with this idea but I have a PDK and I've read this could damage the gearbox. Don't know how true this is. I owned a Z4 prior to this and never once used the parking brake but I can't recall whether the parking brake on BMW's is automatic when you shift it into PARK.

[Maxym]

DallySingh said:

bennno said:

Dont apply the handbrake it its to be left parked for a few days or after washing.

I dont apply it to any of the cars we have in the garage, assuming its manual just put the car in first gear or reverse.

I've toyed with this idea but I have a PDK and I've read this could damage the gearbox. Don't know how true this is. I owned a Z4 prior to this and never once used the parking brake but I can't recall whether the parking brake on BMW's is automatic when you shift it into PARK.

IME the parking brake and 'Park' on a BMW are quite separate.

On a PDK Porsche, I wouldn't worry about leaving it in P with no parking brake on a level surface. I didn't.

[Discombobulate]

DallySingh said:

This makes sense as the knocking sound was only occurring when applying pressure to the footbrake. I imagine my drive to the Porsche garage sorted it as the problem didn't exist once I got there.

I wouldn't say there's any vibration when braking at speed but difficult to tell with the car itself being so loud.

Is this anything to be concerned about?

No. Just makes sure the discs are dry after washing before putting away. Humidity will do the same if the car is laid up for a while. But a bit of throttle to unstick them and some heavy braking should clear any residue.

[ATM]

Maxym said:

DallySingh said:

bennno said:

Dont apply the handbrake it its to be left parked for a few days or after washing.

I dont apply it to any of the cars we have in the garage, assuming its manual just put the car in first gear or reverse.

I've toyed with this idea but I have a PDK and I've read this could damage the gearbox. Don't know how true this is.

On a PDK Porsche, I wouldn't worry about leaving it in P with no parking brake on a level surface. I didn't.

This

Had my PDK 981 for 5 years or more and never never never use the parking brake.

On a slope it will hold the car. Although I can't remember parking on a big slope.

But your problem isn't the parking brake. The pad deposits are from the main brake pads.