I'm having a strange problem with my 01' P5 brakes. On easy braking under slow speeds (usually when doing a slow stopping from 15-20 kph) the car will make slight jerks before stopping. The jerks will be more noticeable when stopping and turning at the same time. And the jerks are most noticeable when I'm just releasing the brake before the car stops to get a smooth stopping.

I must note that when braking heavily on high speeds then there are NO vibrations in brake pedal or neither in car itself.

I'm not sure if this has something to do with the jerking problem but I also noticed lots of little black marks on the brake discs (more on the rear discs).

The dealer offered the discs replacement but as I must then pay for the pads and I'm not sure if this will solve the problem I don't know what to do...

Any ideas?

 

Manual one

 

The P5 started as a 2002 model. I think your braking problem has to do with some contaminants on the brake rotors and/or pads. You might try cleaning them thoroughly with brake cleaner before paying for new pads. If that doesn't work, I'd take the dealer up on the new rotors and order Hawk HP plus pads from the Tire Rack for $60.

 

That's what I thought too, but isn't it strange that after driving for a 3-4 month the contamination doesn't wear off from the pads/discs?


No, this happens when the gear is already in neutral.

 

It would seem strange, but I guess it depends on what it is on the rotors?

 

Maybe you foot is too large and while braking, you are stepping on the gas as well. It's happened to a friend of my with a brand new Sebring and the dealer spent 2 weeks to figure it out.

 

Now that's funny.

 

Definitely not a foot problem cause as I noted above the gear is already on neutral or the clutch is down when this occurs.

 

Exactly, this is what I'm feeling at low speeds. But there's no vibration or pulsation on high speed braking.

What do you mean under buildup on the rotors... ?

 

If your rotors are warped wouldn't you notice the pulsation at ALL speeds when applying the brake (ie. not just at slow speeds)?

 

Yes, it would be more noticable at lower speeds though. It could also be caused by the pads being glazed from overheating. Siimse mentioned that there was some material on the rotor surfaces, so I would still recommend removing them and cleaning them with brake cleaner. Take a good look at the pads while the rotors are off.

 

In my experience those symptoms are indicating normal rotor wear. And the harder the brakes are used the faster the wear sets in. If checked with a micrometer you’ll find that the rotor - it may just be one - varies in thickness slightly as you go around. This is usually caused by a small amount of lubricant that got on the rotor, and started an uneven wear pattern and or glazing. Once started, the uneven wear compounds itself thru harmonic oscillations. That’s why you feel it most at low speeds. If let go long enough and driven hard enough it can lead to a warped rotor thur uneven heating of the disc. Except in the worst cases, turning about 3-7mils off the surfaces will smooth it right out. It’s typical for me to turn the rotors once when I put new pads on, and again when the pads are ½ worn out.

My advice is to ditch the stock pads and have the rotors turned. Be sure to put it back together clean too. No geasy hands on those rotors or pads.

 

right, and if the rotor is/was warped you would feel it under hard braking too. So the above advice is good.
Someone earlier mentioned the Hawk HP Plus pads. If you are worried about rotor wear I would say this isn't the best choice from what I've heard from many other people who use their pads for racing applications. I haven't noticed anything too irregular yet from using the Hawk HPS pads(I put on new rotors at the same time) and I have done about 2k mi. of regular driving, a track day and a couple autocrosses on them. The more aggressive pads cause faster rortor wear. I've heard Performance Friction or Porterfield make good performance brake pads.

 

The Porterfield R4-S pads are very good also, but about 50% more expensive than the Hawk pads.

 

I've noticed that it feels like the brakes aren't stopping my Pro smoothly-- It's not that bad, but enough so that I notice it when making slow, even, stops. Feels like the car is subtly jerking forward and back as you slow down.

As said, this is very subtle, and probably not noticeable to anyone other than me (as I've come to know the car's feel very well now).

The question is, does anyone else get this, and if so, think it's normal for our cars?

If not, I'd just assume have the dealer run a wheel balance under warranty now, if that's the problem. Maybe it's over tightened lug nuts or something...

Thanks, all!