[AW89GT]

New to me 08 GT 5spd with 20k miles. When I hit the brakes after they get wet, either parked in the rain or hitting a puddle, the whole car shudders and groans for a few seconds. Is this typical?

[GOLDENPONY]

No, not typical. You might have warped rotors.

[GreyDiesel]

I actually heard, and I think it was on this forum, that rotors are very hard to warp. What happens is that the brake pads wear in a non-uniform fasion, and you get the same result as if the rotor was warped.

Anyhow, in regard to the original question, might it have something to do with the traction control or ABS? Does it occur as you are coming to a stop? Or after you are completely stopped?

[GOLDENPONY]

Originally Posted by GreyDiesel

I actually heard, and I think it was on this forum, that rotors are very hard to warp. What happens is that the brake pads wear in a non-uniform fasion, and you get the same result as if the rotor was warped.

Anyhow, in regard to the original question, might it have something to do with the traction control or ABS? Does it occur as you are coming to a stop? Or after you are completely stopped?

I don't think this is accurate. Modern rotors are fairly thin, and thin rotors aren't that hard to warp - especially if you over heat them a few times.

[GreyDiesel]

okay, I dont want to be an ass, but this got me curious and I did more research... Here is an article that better explains what I was talking about.

StopTech : Balanced Brake Upgrades

Not that it really matters. After reading the article, it sounds like semantics. Rotors do not technically warp, but they get additional material deposited on the surface which creates uneven thickness and shuddering. Same basic idea.

[AW89GT]

Its not warped rotors. Unless you let the rotors go way too far, you don't notice a warped rotor at 5 mph. This happens when I back out of a parking space/driveway. I'm moving very slow and its only for the first application of the brakes.

[frdfrst]

i've had 5 mustangs thru the years and every one did this till i changed the pads.my 05 i have now has hawk hps's on and this stopped the day i put them on.i have new rotors& pads i'm getting put on shortly as the stock rotors&hps's have about 71000 on them.bought new upgraded rotors&the hps's for under $300 at rotorpros on ebay.

[AW89GT]

Interesting. Thanks