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Discussion Starter #1
In older high end cars like the Ferrari and the Aston Martin, there was a 2nd caliper on the rear discs that would hold the car when the parking brake was engaged. My BMW 3 series had a rear drum brake inside of it that the handle was connected to. Then cars like my Audi switched to an electronically activated switch that would engage the rear caliper without hydraulics. I'm not clear on whether it presses the piston or separately clamps the caliper, but it's my rear brake pads holding the car.

What does the 981 do when the parking brake lever is pulled? I can't visibly tell a difference when it's engaged or disengaged.
 

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In older high end cars like the Ferrari and the Aston Martin, there was a 2nd caliper on the rear discs that would hold the car when the parking brake was engaged. My BMW 3 series had a rear drum brake inside of it that the handle was connected to. Then cars like my Audi switched to an electronically activated switch that would engage the rear caliper without hydraulics. I'm not clear on whether it presses the piston or separately clamps the caliper, but it's my rear brake pads holding the car.

What does the 981 do when the parking brake lever is pulled? I can't visibly tell a difference when it's engaged or disengaged.
Pretty sure this is how Porsche does it as well.
 

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Discussion Starter #4
No, the Audi is a 1 finger switch in the center console. The Porsche is a four finger lever, like what you'd use to pop the hood.
 

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There's a drum brake inside the rear rotors. Upgraded my rotors so I've seen it.


Mike
Sounds like extra unsprung weight to these uneducated ears. ;)
 

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Discussion Starter #9
The boxster has little miata rotors. Not much unsprung weight to lose there. The wheels already bounce off of things.
 

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There's a drum brake inside the rear rotors. Upgraded my rotors so I've seen it.


Mike
That I would like to see, do you have a picture?
 

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Can't speak to the drums, but recently I swapped to snow tires, so I had the car up on jacks and I can confirm that with the e-brake, only the rear 2 wheels are stopped. The front 2 wheels are still free to spin with the e-brake engaged (at least for a 2013BS - doubt they would've changed that moving forward tho)
 

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When used as a parking brake, it makes sense that only the rear wheels are braked. That's just how parking brakes are supposed to work.

My impression from reading the manual, however, is that if you press the e-brake switch while driving it will effectively drop anchor and emergency brake to the best of the car's ability. Has anyone actually tried this?
 

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When used as a parking brake, it makes sense that only the rear wheels are braked. That's just how parking brakes are supposed to work.

My impression from reading the manual, however, is that if you press the e-brake switch while driving it will effectively drop anchor and emergency brake to the best of the car's ability. Has anyone actually tried this?
Cluck, cluck CLUCK! :hilarious:
 
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When used as a parking brake, it makes sense that only the rear wheels are braked. That's just how parking brakes are supposed to work.

My impression from reading the manual, however, is that if you press the e-brake switch while driving it will effectively drop anchor and emergency brake to the best of the car's ability. Has anyone actually tried this?
981WC has. From memory he reported it was not dramatic but just a gradual speed reduction.
 

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Revived this thread to see if now that the 981 has been around for more years, if somebody know EXACTLY how the electric parking brake holds the car. There must be some kind of brake shoe arrangement in there, since there's an internal drum inside the rear rotor (drum-in-disc). What has me stumped is the actuator is freaking plastic, and about 2" long. And it's at an angle that almost looks like it's acting on the rotor itself, not the inner drum. So curious if somebody has pictures or cutaway graphs to show exactly how it works internally.

As a side comment, when I received my car, it was on a freaking 45º ramp (in reverse). Not only the guy must have beat the crap out of my PDK to climb it there, but I wanted to ask the gang if somebody knows how steep the electric parking brake holds the car. I really doubt it can hold the car at that extreme angle, but wanted to ask. Most mechanical parking brakes only hold the car at a moderate angle, and usually a lot better in one direction than the other. Anyway, the guy must have had to really yank on the PDK lever to get it out of P at 45º. And of course he scraped the bottom of my car next to the wheels, and even chewed a little on the inside of the wheels. At least the lip and underbumper was undamaged, so it's obvious it was transport related, not hitting a parking stop or something.

EDIT: Found a couple of pictures of just the actuators. The first, a Panamera's system, the actual (plastic) actuator looks identical to our 981s, but they go directly into the hub, rather than a separate housing, like the Panamera part shows. However, there's a possibility it's the same inside. The other photo shows the actuator on a Passat, but has a gear, instead of 2 prongs that extend out. Something is obviously rotating, but I'd like to know how the rest of the system actually activates the parking brake. Couldn't find anything. And yes, sometimes I hate being an engineer, wanting to know how everything works;). My main curiosity is if the actuator is actually compressing pads against the inner drum, or physically locking it somehow, hence being able for a plastic part to do the rotating job. When I engage the parking brake, the car rolls a couple of inches first, then it doesn't move. Feels exactly like the parking feature on PDK (and other autos). That shouldn't happen when pads are compressed: wheels don't move if applied strong enough. Thank you for listening:).
 

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Since we are talking about the emergency brakes in a 981 I thought I would snap a picture of the ones in my BGTS...

Must remember to do some spring cleaning in there! ;)

 

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