Blue4Ice

I think I have one (maybe 2) issues with my front brakes on my 968.

Quite often when I start the car and pull away I hear what sounds to be a calibration type noise (almost like a motor moving into place). I am not sure if this is something to do with ABS calibrating?

The reason I say this is that sometimes when braking (not all the time) I hear a similar noise and the pedal travels a lot further and braking efficiency is a lot less (i.e. it takes me longer to stop).

The front brake pad condition looks ok. The discs are a little worn (a small lip at the edge of the disc) but have life left in them.

Any ideas?

Thanks

jpk

It sounds like an issue with the vehicle speed sensors at one of the wheels. If your speedometer goes all wonky when you brake, it's the left front. Otherwise it could be any of the other three.
You need to get the rotors off to check them. You'll see the sensors mounted slightly above what looks like a gear with the pointy teeth ground flat.
I'm sure there's a spec for the proper gap in the service manuals. If that checks out, look at the condition of the electrical connection where they plug into the harness.

968rz

Normal noise, that's the sound of the anti-lock pump priming. I make it almost to the end of my drive when I hear it.

odurandina

i have a fresh set of front rotors for sale...

they are at spec. about 8 thousand miles on them and showing almost zero wear.

also have the calipers if anyone is interested in my brakes.

Blue4Ice

Thanks for the response guys. I am glad it is a normal noise.

Any idea why my brake travel could be a lot longer from time to time? Could this be something like master cylinder?

Thanks
Steve

PorscheDude1

Have you checked the fluid level?
When is the last time the brake system was flushed?

Yarf

Check the wheel bearings for play?

RajDatta

+1 on ABS sensors and ABS pump. Looks like something is throwing off a reset of the ABS pump. As far as sensor adjustments, there aren't any on 968's. You pretty much bottom out the sensor to its mounting point. You could potentially have some debris caught up on the hub teeth or it could be that one of the sensor magnets has picked up debris. I would start by removing sensors, cleaning them and spraying brake cleaners on the hub gears.
Also, inspect the hub gears to make sure there is no wear marks on them.
Regards.

Blue4Ice

Thanks again for the replys

PorscheDude1 - I haven't checked it in my ownership (since Aug 09) but it has full Porsche service history so would have been done when required a few years back. However I will check it for level and am planning on getting it changed at the next service.

Thanks for the info on the sensors and the pump. I will check the sensors for damage/debris. Does anyone have a link to a diagram of this area so I know what I am looking for?

RajDatta

It's easy to find. The sensor has a cable going to it and is mounted with a hex head bolt. There is one on each hub. It is inserted into the hub and is of a cylinderical shape.
Regards.
Raj