spongy brakes after replacing pads and rotors-help needed
Thread Starter
Newbie
Joined: Jul 2007
Posts: 2
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From: Colorado Springs
2003 CLK 500
spongy brakes after replacing pads and rotors-help needed
I replaced pads and rotors all the way around on my 03 CLK500 with 69,000 miles but after bedding them in the brake pedal became "spongy". I already put around 1000 miles on the car but no change in brake feel, it goes about 2" with minimal braking and then grabs. I put cross-drilled rotors and ceramic Posi-quiet pads from R1 performance. When working on brakes I did not bleed any of the calipers, I disconnected ABS plug, and did not add any brake fluid. What possibly may be causing the "spongy/soft feel"? Prior to replacing rotors and pads brake felt like it supposed... is there something that maybe I missed? 
Any help is really apprieciated...
Any help is really apprieciated...
MBWorld Fanatic!
Joined: Apr 2005
Posts: 3,784
Likes: 84
From: SCV SoCal
2002 CLK430
For lousy pedal feel, the cure may be cheap. My Pumas have felt their share of spongy pedals, and typically, it’s the fluid. Personally, I'd change the brake fluid. Not just bleed them, but change it. The fluid is supposed to be changed once every two years anyway, so you may be due. It’s changed every two years because brake fluid is hygroscopic. While it's corroding the brakes, that absorption of water will cause the pedal to get spongy over time. I change the fluid while doing the pads/rotors, as it’s the perfect time. At that point, the car is in the air, the wheels are off, and its naked calipers are easily accessed. Like they say in the commercials, “when the time is right . . . . . .”
As for the brakes feeling grabby, that sounds like it may be the new pads and rotors. Did you bed in the brakes after installing the new pads and rotors? If you have no idea what I’m talking about, here’s a write up on bedding in brakes.
Also, if the finish on the rotors is too rough, they’ll grab. A bad finish on a new rotor can be caused by the manufacturer of the rotor finishing them on a lathe too quickly. Time is money, so some manufacturers feel the more rotors they crank out, the more money they’ll make (that’s a nice way of saying their unfinished product is cheaply constructed). To tell if they’re too rough, run your fingernail along the rotor in the same direction as the pads would pass. If you can feel the grooves with your fingernail, the rotors aren’t smooth enough. Not knowing the makeup of your pads, I can’t comment on them. However, ceramic pads are not known for their effectiveness.
As for the brakes feeling grabby, that sounds like it may be the new pads and rotors. Did you bed in the brakes after installing the new pads and rotors? If you have no idea what I’m talking about, here’s a write up on bedding in brakes.
Also, if the finish on the rotors is too rough, they’ll grab. A bad finish on a new rotor can be caused by the manufacturer of the rotor finishing them on a lathe too quickly. Time is money, so some manufacturers feel the more rotors they crank out, the more money they’ll make (that’s a nice way of saying their unfinished product is cheaply constructed). To tell if they’re too rough, run your fingernail along the rotor in the same direction as the pads would pass. If you can feel the grooves with your fingernail, the rotors aren’t smooth enough. Not knowing the makeup of your pads, I can’t comment on them. However, ceramic pads are not known for their effectiveness.
