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Originally Posted by blinkwatt
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"?
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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
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