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How to fix E65 E66 BMW 7 Series Parking Brake Actuator Failure – Plastic Gears vs Metal Gears

BMW 745 Li

BMW 745 Li

Standard intro – “Just rolled into the shop…”

We had a client come in with a parking brake that was staying stuck on. This obviously was causing all sorts of issues:

  • It was dangerous as the parking brake was applied at all times – even while driving around, changing the driving dynamics of the vehicle.
  • It was causing aggressive wear and tear on the parking brake shoes and rear brake disc. This customer drove far enough that the rear brake shoes had actually melted and needed to be completely replaced.
  • It was causing the parking brake active warning light to stay illuminated while driving – bringing undue stress on the driver. (We all hate ignoring those dash lights!) If you see this we highly suggest towing the car to avoid further damage to the parking brake system.

Upon inspection we discovered that the original gears in the actuator are plastic. Over time the plastic becomes brittle and cracks causing the unit to fail. As a result the actuator was unable to turn the gear and release the parking brake.

7 Series Parking Brake Actuator Recess Located in Trunk

7 Series Parking Brake Actuator Recess Located in Trunk

Here we have the trunk of the BMW 745 Li open. We had to remove the spare and the liner to access the actuator.
7 Series Parking Brake Actuator Recess

7 Series Parking Brake Actuator Recess

Here’s a close up of the recess where we removed the actuator.
7 Series Parking Brake Actuator with Gear Removed

7 Series Parking Brake Actuator with Gear Removed

Here’s the Actuator itself (with the gears removed.
7 Series Parking Brake Actuator Broken Plastic Gear

7 Series Parking Brake Actuator Broken Plastic Gear

Here’s the original gear. It turns like a corkscrew tightening and loosening the parking brake cables. You can see the plastic gears chewed themselves up and broke.
7 Series Parking Brake Actuator Stronger Metal Gear

7 Series Parking Brake Actuator Stronger Metal Gear

Now here’s the special part. Using a combination of ingenuity, experience, and a career building strong connections (read Google search), our technicians not only found a fix that cost our client less than replacing the whole unit, but less than the standard plastic replacements. On top of that the metal gear will last much longer than any plastic replacements. Hopefully meaning this issue is fixed for good!
7 Series Parking Brake Actuator Plastic and Metal Gear

7 Series Parking Brake Actuator Plastic and Metal Gear

Here’s a comparison of the plastic and metal gear pieces.

We’d love to hear your thoughts on the modernization of systems that may not need updating. Like the electronic parking brake with motors and gears vs. a standard lever actuated parking brake. Also, what (if any) “better than OEM” replacements have you found?

2 Comments

  1. Stefanie on August 5, 2018 at 7:06 pm

    Gotta love finding a great solution! I just replaced mine as well with a full metal gear…but, my dash light didn’t go out and the OBDII doesn’t show a code/error that can be cleared. How did that process work on this vehicle?

    • Big Jon on September 6, 2018 at 4:30 pm

      Stefanie, thanks for reaching out, but this is something we’d likely have to look at to help with. In this case the light cleared when we were done so it didn’t require any extra troubleshooting.

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