TimC

2 brake issues -

1) I am noticing some brake fade (on 88na) - brakes fade even after one moderate stop (say from 100 to 0 down long exit ramp). Typical or excessive? I tend to think the latter, as most road tests of various Porsches have always lauded their fade resistance, but actual user experience may vary I suppose.

2) I am also getting a rumble type of noise under all but the lightest braking. What the heck?

Any ideas/comments on the above, thanks in advance.

Tim C.

TimC

PS - car not equipped with ABS, in case anyone was thinking the rumble might just be ABS actuation.

TC

Dave

Have you looked at your pads?

billybones

Rumble and fade, warped rotor... when was the last time you packed your bearings.. Most likley a bad rotor. If the face of the rotor moves in and out on the brake pad fast enough the hydraulics of the braking system can not keep up with the wobble..thus fade and rumble..

billybones

One more.. if your pads are shot and you did not chase your fluid level in the resivoir..you might have gotten air in the system...

TimC

Fluid levels fine, pads fine. If rotors are warped, they sure aren't warped significantly.

T

Skip

First thing to do in a case of fading is flush the system. Especially if the fluid was synthetic, there could be a significant buildup of water in the system. Enough to cause fade under light braking. If there was water in the system it may have caused corrosion or rust in the calipers... which could lead to a rumble... though quite unlikely. Warped rotors are easiest to check under light braking... just let loose of the wheel and check for a braking induced shimmy. Of course all rotors are somewhat warped, it's just the degree of degredation that's acceptable.

Rumble under braking is normaly caused by a worn wheel bearing. The load of the bearing in the driving position is relaxed and stable (comparing accumulative braking time to driving time). Under braking the load of the bearing changes slightly, which can give clues to the bearings' condition. Give the wheel a shake to check for clunking. If it's there, then you'll have to investigate further to determine the actual cause. Could be ball-joint, tie-rod, strut, etc...

To improve your fading characteristics, you might consider a performance fluid such as ATE Super Blue or the like.

Good Luck!