1994-2002 [Subscribe to Daily Digest] |
The inner pad is acted on directly by the piston. If that piston did not move outward properly you would have reduced braking. There are two other possible issues. If the slider bolts are not moving properly then the floating caliper would not allow for pressure sharing with the outer pad. If the bolts slide, the pressure is the same on both. So before you replace the pads, force the inner pad inwards and then grab the floating caliper and try to move in inward and outward. Look for damage to the rubber boots that accomodate that movement. When the brakes are working, the large forces are taken up, not by the slider bolts, but by the contact surfaces between the fixed and sliding calipers. Check that these are not rust bound or binding. I put some oil in these gaps, as that will flow, then some grease over that. If things are apart, you can just use a hi temp brake mechanism grease. If there is rust, you may have to take things apart and remove the rust deposits.
So if the caliper is floating properly, brake forces are identical and wear should be very even. So now you know what to look for.
If the piston was binding, and the caliper slides were ok, wear would still be even. If the piston is hard to push back in, that could be a sign of problems with the piston seal. When the pads are out, you can visually inspect the outer boot for damage.
I had 130000 miles on my orignal pads and rotors on the front at 6.5 years, and could have gone another year. The rotor surface was perfect, with a wear lip of course. So that is what one can expect with the right pads and a highway commute service. It seems that Saab has changed to abrasive type pads. It is so bad on newer 9-5's that many remove the pads on a new vehicle and install EBC pads to preserver the rotors. With the large rotors on the Aero's that could avoid a rather costly repair. Remember that these are a wear item, so no warranty if pads are too abrasive. The EBC pads are kelvar, and a thin film of degraded poymer is deposited on the rotors. When the brakes apply, you get a viscous type friction instead of purely abrasive. So there are pads which are more viscous than abrasive and there is an iteraction that is somewhere between fluid and adhesive.
posted by 207.43.195...
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