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Old 10-28-2016, 05:45 PM   #1 (permalink)
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Default "Cleaning" brake disks

With little use of the brakes (especially when using HILL 1 or 2) the rear disc will easily corrode. If more than 25% of the surface is corroded they need to be changed in order to pass MOT (or similar in Europe).

On my BMW i3 I engage the handbrake every now and then to keep the surface of the rear discs clean.

Anyone who knows if this is possible also on the Karma?

I can of course try, but I am a bit concerned to do anything which can mess up something.

Or any other suggestions?


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Old 10-28-2016, 06:13 PM   #2 (permalink)
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Are you talking about applying the parking brake while driving? A-r-r-r-g-h! (Is that even possible??)

Seriously, if you're not moving and the parking brake is engaged, and then you select "D," besides the bright warning light on the dash, you'll hear a VERY loud, high-pitched alarm. Has anyone ignored all of these warnings and tried to move forward with the parking brake engaged? I doubt it.

But for some reason, "R" doesn't have that screaming alarm. And it is possible to backup - although I would also be worried about doing major damage to the drive train.

Then again, the lack of the alarm may mean Fisker intended backing up a bit with the parking brake engaged as a means to avoid rear disc corrosion as was suggested.

Anyone know?
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Old 10-28-2016, 08:31 PM   #3 (permalink)
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I have had my Karma since 2012 and now have 40,000 miles. I just inspected and applied Dupont MolyKote on the caliper side of the pads to prevent squealing. During the inspection, here in Georgia (hot and humid, but little or no snow), the pads and rotors are like new in appearance. I surmise that the contact of the brake pads when backing, parking and some stopping is sufficient to "clean" the rotors.

CSP's please weigh in to my lay experience.
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Old 10-29-2016, 03:06 PM   #4 (permalink)
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@Ira, thanks for your feedback - no, have not yet tried, but on my BMW i3 this is done without any problems an any alarms, it just cleans the discs (and brakes the car of course). Also, the i3 regular engage the brakes very shortly for some reason (a small "clunk") can be heard when starting I have read on the i3 forum this is done to keep the discs clean.

Corroding discs is a problem in colder, wet areas, as where I live (Oslo, Norway). Just had my Land Rover Defender for it first MOT, and will have to change the rear disks just because they have started to corrode - the car is regularly used. On Defender, you cannot engage the hand brake, since this is not applying brakes, but brakes the "axle" between the front and rear axles, and my cause serious damage.

It is possible to engage the hand brake as an "emergency brake" on many cars, it is even written in some owners handbook.

I have not had the courage to do this on my Fisker - what I save on disks, may cost a lot more if I destroy the drive unit or some other things.......hence I ask the wise men on this forum.

Thanks.

Last edited by tbjorge; 10-29-2016 at 03:08 PM.
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Old 10-29-2016, 06:41 PM   #5 (permalink)
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There are at least 3 (or as many as 12) wise men on this forum.
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Old 10-31-2016, 08:46 PM   #6 (permalink)
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The parking brake switch serves as emergency brake by pulling the drum-in-hat cable to slow the vehicle all the way to a stop, if necessary.

If the rotors are corroded, find an open parking lot free of obstacles, may need several applies to totally clear the rotors. (Try to avoid doing this on a public road unless the situation calls for it, which is highly unlikely.)

Below 20 mph (32 kph) the motor/puller will ramp to 90% max within 5 sec as long as the switch is held continuously. After stopping the puller will hold the vehicle with the park brake function. (A low speed park brake apply was used in the factory to burnish the brake rotors.)

Above 20 mph there's a step-wise operation called through different algorithm, so the vehicle response may feel different. Ramp to 90% pull still happens over about 5 sec. This routine is intended to slow the vehicle from highway speed within the required distance and deceleration rate. Same as the low speed, the park brake function then holds the vehicle. See note below on 'hold time'.

Releasing the park (emergency) brake switch at any time during deceleration will release the cable puller from drum-in-hat brake.

Hold Time:
Holding the switch longer than 10 sec may result in a brake release or an error message in the cluster. For higher speed deceleration multiple pulls are recommended to slow the vehicle to a stop, say once every 8 sec or as required.

Of course, be sure to check your owners manual because your mileage may vary.
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Old 10-31-2016, 11:51 PM   #7 (permalink)
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I think if you hold the parking brake too long while driving and have over a 50% charge there may be some unexpected consequences.


Last edited by DHH; 10-31-2016 at 11:54 PM.
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Old 11-02-2016, 03:59 PM   #8 (permalink)
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Thanks to FAChassis, very comprehensive answer. Seems it should be rather harmless with the right circumstances - just need to check that my car is not equipped with ejector seat(s).....never know what these cars have hidden
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Old 11-17-2016, 08:42 PM   #9 (permalink)
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Quote:
Originally Posted by FAChassis View Post
The parking brake switch serves as emergency brake by pulling the drum-in-hat cable to slow the vehicle all the way to a stop, if necessary.

If the rotors are corroded, find an open parking lot free of obstacles, may need several applies to totally clear the rotors. (Try to avoid doing this on a public road unless the situation calls for it, which is highly unlikely.)

Below 20 mph (32 kph) the motor/puller will ramp to 90% max within 5 sec as long as the switch is held continuously. After stopping the puller will hold the vehicle with the park brake function. (A low speed park brake apply was used in the factory to burnish the brake rotors.)

Above 20 mph there's a step-wise operation called through different algorithm, so the vehicle response may feel different. Ramp to 90% pull still happens over about 5 sec. This routine is intended to slow the vehicle from highway speed within the required distance and deceleration rate. Same as the low speed, the park brake function then holds the vehicle. See note below on 'hold time'.

Releasing the park (emergency) brake switch at any time during deceleration will release the cable puller from drum-in-hat brake.

Hold Time:
Holding the switch longer than 10 sec may result in a brake release or an error message in the cluster. For higher speed deceleration multiple pulls are recommended to slow the vehicle to a stop, say once every 8 sec or as required.

Of course, be sure to check your owners manual because your mileage may vary.

I tried this on my own car and it does not work? Has anyone else tried it? Seemed to just lock up the parking brake and then got an error?
@FAChassis are you available for a meetup where owners can videotape the proper way to engage this function? I can provide 3 cars for an autocross session from California to the East Coast. Please advise. This is very important information that we all need to know about! Thanks
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