Auto Hold/Parking Brake

[GolfTi]

I was a little concerned about the e brake/hill hold and stop/start.

It actually works very well indeed and you can more or less forget about it and let the car do its thing.
It does insist you wear your seatbelt though.

The anti collision system is very impressive too, even with the cruise control off it will warn you in the display if you are getting too close, then if you get really close it will show a large red warning in the display along with an audible warning, and apply the brakes.


Serious tech.

[Gordor]

The tech is fantastic and never let me down in the A4...I now find it frustrating when driving the wife's car because I have to manually apply and dis-engage the handbrake (Which I have forgotten to do on a couple of occasions) 

[CraigW]

The tech is fantastic and never let me down in the A4...I now find it frustrating when driving the wife's car because I have to manually apply and dis-engage the handbrake (Which I have forgotten to do on a couple of occasions) 

Doh!! 

[Sootchucker]

Actually the electronic handbrake in the MK7 is probably more secure than a cable version. As you know in a cable version, the cable pulls on a lever cam which exerts pressure on the brake piston and forces the brake pads against the disc.

In the mk7, there isn't a cam but rather an electric motor which has a worm gear on the end. This engages with a pinion which is attached to another worm drive which is part of the caliper piston. Therefore, when the handbrake is applied, the electric motor turns very briefly and using the gears the piston is actually screwed up against the pads and discs mechanically. Furthermore, a torque and current sensing circuit measures the torque being applied to the pads but the motor and is measured each time the brake is applied. This automatically adjusts for pad wear and ensures that the pads are always pressed against the discs at the optimum pressure irrespective of pad thickness. No handbrake cable to adjust, stretch, snap etc.

In the unlikely event of an electric motor failure, there is an override pinion behind a hidden cap that can manually disengage the worm drive and allow the rear discs to be released for driving or towing to a dealership with no effect on the basic braking system at all.

Oh yes, and on DSG equipped models, when in Park, a locking pin engages with the flywheel locking the transmission and effectively giving 4 wheel handbrake.

Genius really.

[monkeyhanger]

Actually the electronic handbrake in the MK7 is probably more secure than a cable version. As you know in a cable version, the cable pulls on a lever cam which exerts pressure on the brake piston and forces the brake pads against the disc.

In the mk7, there isn't a cam but rather an electric motor which has a worm gear on the end. This engages with a pinion which is attached to another worm drive which is part of the caliper piston. Therefore, when the handbrake is applied, the electric motor turns very briefly and using the gears the piston is actually screwed up against the pads and discs mechanically. Furthermore, a torque and current sensing circuit measures the torque being applied to the pads but the motor and is measured each time the brake is applied. This automatically adjusts for pad wear and ensures that the pads are always pressed against the discs at the optimum pressure irrespective of pad thickness. No handbrake cable to adjust, stretch, snap etc.

In the unlikely event of an electric motor failure, there is an override pinion behind a hidden cap that can manually disengage the worm drive and allow the rear discs to be released for driving or towing to a dealership with no effect on the basic braking system at all.

Oh yes, and on DSG equipped models, when in Park, a locking pin engages with the flywheel locking the transmission and effectively giving 4 wheel handbrake.

Genius really.

That does sound foolproof. If only the engineering side could sort out the allocation system.

[dubber36]

No one has mentioned the "emergency brake" function yet.

It's not the most intuitive thing to do if you find yourself in a situation where you have to stop very quickly, but pulling up on the parking brake switch will brake all 4 wheels with more force than you could supposedly apply using the pedal. It also puts the hazard lights on.

[Bill_the_Bear]

No one has mentioned the "emergency brake" function yet.

It's not the most intuitive thing to do if you find yourself in a situation where you have to stop very quickly, but pulling up on the parking brake switch will brake all 4 wheels with more force than you could supposedly apply using the pedal. It also puts the hazard lights on.

Won't you lose the ABS though?

[dubber36]

No. Pulling the toggle whether to emergency brake, or park the car applies the brakes in the same way that pressing the pedal does. The wheel speed sensors will still recognise a potential skid, and the ABS will do it's thing.

I tried this out in my Passat and it does work. I nearly went through the windscreen. 

It's also a useful feature as I was able to keep my finger poised over it when I was in the passenger seat and my 9 year old lad was having his first drive.

[Bill_the_Bear]

No. Pulling the toggle whether to emergency brake, or park the car applies the brakes in the same way that pressing the pedal does. The wheel speed sensors will still recognise a potential skid, and the ABS will do it's thing.

I tried this out in my Passat and it does work. I nearly went through the windscreen. 

It's also a useful feature as I was able to keep my finger poised over it when I was in the passenger seat and my 9 year old lad was having his first drive.

Hmm, I'm confused.  Norbreck21a described the electronic parking brake as electric motors, but isn't the foot bake and ABS hydraulic?  Are they not two different systems?  I must be missing something here.

[dubber36]

Sorry I'm confusing the issue here.

Yes the parking brake uses electric motors to apply the rear brakes. The Auto Hold uses the hydraulic system on all four wheels. Even tho' is is activated using the "hand brake" button, the Emergency Brake operates the hydraulic system in the same way that pressing the pedal would.