How to tell if its time for a brake pad change?
 

Besides the Brake Wear light coming on,is there a certain thickness that the pads should be before they are changed?

Hi,

You actually should change out your Pads before the Wear Indicator comes on. First, you don't need to replace the Wear Indicators, but second, by the time the Wear Indicator does light up, your Braking Efficiency is reduced.

But, you should also check the Rotors as well. The Pads should be changed when the Pad material (not including the Steel Backing) is down to 10.0mm (0.39") for the Fronts or 8.5mm (0.33") for the Rears. The Rotors acceptable wear limit is 22.6mm (0.89") for the Fronts and 18.6mm (0.71") for the Rears. You'll need a Micrometer to properly measure both the Pad and Rotor Thicknesses.

Also, if the Rotors are cracked or deeply scored, or if Runout exceeds 0.03mm (Free or 0.06mm when mounted on the Hub), these should also be replaced. Hope this helps...

Happy Motoring!... Jim'99

What is the Runout you speak of? Who makes the OEM pads for a 99'? I heard the Pagid pads don't have wholes for the wear sensors,is this true? Anyone have any expierence with Mintex pads on a non "S"?

Pagid pads do have the holes for the wear sensors, they are a straight drop in. We use them exclusively on almost all of our pad changes (There are a few models here and there that we use textar). I list textar and pagid as OEM pads.

Just changed the pads and disks (rotors) on my 'S'.

Standard pads are Textar and disks were Sebro. Replaced with the same.

The problem on the 3.2 (not sure about 2.5 and 2.7) is not so much the disks wearing out, it is more a problem of corrosion. This is a recognised problem with the Boxster. My disks looked a bit worn, and I decided to replace them. When I did, and looked at the backs of the ones I removed, the surface was actually broken up in a few places due to really bad corrosion.

I always make sure the disks are dry after washing the car and parking it in the garage. If I didn't do this, I'd hate to think what sort of condition the disks would have been in.

Hi,

Lateral Runout is side-to-side motion in the Rotor as it turns on the Hub. This erratic motion in turn causes uneven wear in the Rotor. As you drive, even without the Brakes applied, the Rotor hits the Pads lightly on each revolution.

This extra wear leaves a thin spot on the Rotor. Once this thickness variation is worn into the Rotor, the Bake Pedal will vibrate when braking, and the Rotors' integrity can be compromised and either crack or worse case - shatter.

Lateral Runout is most often the result of small inconsistencies in the Rotor and Hub that, when combined, are often magnified.

Runout can also be induced by uneven Wheel Torque (Lug Nuts should always be Hand-Tightened to correct torque), improperly adjusted or worn Wheel Bearings, corrosion, or damage from hitting a curb or pothole. Any of these conditions can easily lead to poor brake performance that will worsen over time.

You check for Lateral Runout by using a Dial Indicator. You place the Dial Indicator against the Rotor and slowly spin the Rotor, watching the Dial for variations. For the Boxster, the Lateral Runout limit for the Rotor is 0.03mm (a very small variation) or 0.06mm when installed on the Hub (as this takes into account the variations of the Hub, Bearings etc. + those of the Rotor).

You can find a Dial Indicator on the Web, usually for less than $100, often less than $75 (eBay, Harbor Freight, Northern Tools, etc.) and it's a good tool to own as there are many other uses for it.

If you find the Lateral Runout exceeds the limits posted above, you should replace/machine the Rotor.

Given the very small allowable machining tolerance from Porsche, I personally would avoid machining the Rotors on a Brake Lathe, especially on a Tracked or Spiritedly Driven Car as exceeding the Machining tolerances (which would probably be needed to eliminate the Runout) will compromise the strength of the Rotors. Hope this helps...

Happy Motoring!... Jim'99