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Ditching the brake pad wear sensors |
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My 964 Why a 964 C2? My 964 Images featuring my 964 Improving the driving position Upgrading the suspension Upgrading the brakes Goodbye brake wear sensors! Mounting a fire extinguisher 15th Birthday present
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There are numerous descriptions available on the Web that deal
with how to change brake pads on a Porsche. A particularly fine
one can be found
here.
So why do I bother? Because I took some slightly different
pictures, and because there's one thing we did that isn't
covered in excruciating detail elsewhere: how to get rid of the
brake pad wear sensors. These sensors are a complete pain in the
behind. I grant you that they are eminently useful if you never
take the wheels off your car, but anybody who changes his brake
pads often can tell you that they get in the way, and no matter
how careful you are there's a good chance that they'll break
anyway.
Let's start at the beginning, though. Even though I hate disclaimers, I'll put one on this page anyway: use your brain if you act on the information provided here. You're messing with the thingies that stop your car. There are consequences to making modifications like the one described here. Don't sue me if it gets you into trouble; jump off a tall building instead. Please. Right, where were we? OK, just beginning. When working on a car it's extremely useful to have some space around you. Where I live, I don't have that kind of space. I can't even open both doors fully when the car's in the driveway. Fortunately a mate of mine, Adri, has a mate who has a full-size lift in his garage. That mate was kind enough to let us play with my car on his lift. Adri was kind enough to do a lot of the work.
Getting the quite low 964 on the lift was a bit of a challenge, but with some improvised ramps we were good to go. The brake discs were still in good condition, despite more than a little track usage. The Pagid Orange pads, true to their name, had deposited a lot of orange dust everywhere.
The first step was to loosen the clip that holds the pads in. This is done by pressing the narrow bits in the center of the cross together by a pair of plyers. When this is done, you can swing the clip open: it hinges from the top of the caliper. The P-car DIY pages has an excellent description with pictures to show this in more detail.
Unplugging the wear sensor requires opening the cover of the cylinder-shaped plug connector. Once it's open, it no longer grips around the wear sensor plug.
Once this is done you can slide the brake pads out, and replace them with new ones. The unplugged wear sensor got a special treatment. The way the system works is that the brake pad wear warning light comes on whenever the electric circuit through any of the wear sensors is interrupted. Fooling the system is therefore easy: you take the wear sensor, cut the wire near the plug, strip the ends of the two wire strands, and you twist them together.
While this is enough to get the job done, it's not very neat nor very weather-proof. To make sure that the twisted wires continue to make contact for a very long time, we soldered them together using a slightly oversized soldering iron. Because it was so big, it was much easier to clamp the soldering iron into a fixed position instead of clamping the plug.
Once the two wire strands were soldered together, we bent the wire back on itself. This way it is both shorter, less flexible, and thicker.
Both the thickness and the rigidity comes in handy when shoving the rubber insulation back on it. Cutting it down to approximately twice the length of the folded-back wire works very well. Having put the cut-down insulation over the bent-back wires, you can fold the empty part of the insulation back over the wires. It is then fixed in place with a tie-wrap. You'll find that it's much easier to get the tie-wrap ready by inserting the tongue into the little ratchet before messing with the insulation. If you have a prepared tie-wrap ready to go it's easy to slide it over the doubled-up insulation and pull on it firmly to secure everything in place.
The end result is a weather-proof plug that ensures the brake pad wear circuit isn't broken. Should you ever wish to go back to using wear sensors, you just unplug these shorted plugs and replace them with the full brake pad wear sensor harnesses.
As we had an air compressor handy, Adri took the opportunity to blow out the brake dust that had gathered in the rotors.
All of this can be accomplished in relatively little time with a minimal set of tools. The most exotic tool of the afternoon was a torque wrench to tighten the wheel nuts to the specified 130Nm.
Before we went on our way, I took a picture of Adri's support vehicle with my 964 in the foreground.
This little mod will make life a lot easier if you
change your brake pads often. It will save money because the
sensors will break once in a while. It will save you the
annoyance of a lit warning light in the dash.
It will also no
longer warn you when your brake pads are about to wear down to
metal on metal. Then again, if you change the pads often, you
will notice when the pads are getting thin.
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