500 miles on my SRT8, I need new brakes ?

[Moose]

Originally Posted by DZeckhausen

If you consider one of the performance aspects of the rotor to be its expected lifetime, then this most certainly does affect performance! The pads on the SRT8 are so aggressive that I anticipate many customers will reach minimum thickness in just a few thousand miles.

When you design a brake package for a street car, you don't make "high performance" the number one criterion at the expense of all other considerations. You don't see this sort of issue with Porsche, Ferrari, or Lamborghini cars fitted with factory Brembo brakes, nor do you see this with the latest Dodge Viper, Subaru WRX STi or the Mitsubishi EVO VIII. There's nothing specific to Brembo calipers and/or big rotors that requires the brake package be noisy or chew up rotors in 500 miles. This all comes down to the inappropriate selection of brake pads for a street application. Either the pad manufacturer has poor process control and there is a problem with particle size consistency in the friction compound, or the compound is not appropriate for street driving. It's as simple as that. Pick a better pad and the problems will go away.

That statement makes me lean toward a pad manufacturing problem as the cause. On the other hand, the cars may have been driven so aggressively during testing that they were essentially under race conditions. Certain race pads (e.g., Hawk Blue) are quite rotor friendly when running at 500 degrees F, but are incredibly abrasive when run at the lower temperatures one might expect to find during normal street driving. So it's possible that SRT Engineering didn't perform adequate "everyday driving" tests on the SRT8 prototypes.

The letter was updated on 12/29/2005, yet it still claims the resolution will be available in September of 2005 (last year). That's a bit odd. You would think they would revise the availability date to some time AFTER the letter was updated.

Bottom line - this problem will be solved by the aftermarket in spite of the best efforts of SRT Engineering. I expect the new Hawk Performance Ceramic pads will eliminate the rotor scoring issue. The only catch may be an increase in pedal effort. I have no idea what the operating coefficient of friction (Cf) of the factory SRT8 pads is. If the Hawk pads have a much lower Cf, then pedal effort will increase in proportion to the change.

DZeckhausen, I read your earlier post regarding this and I can't agree more. It's nice, and the reason I'm a member, that we have crafty knowledgable people like yourself to draw from on this forum. Thanks for the great input.

Moose.

[CVC22348(b)(1)]

Took my car in for its first service. 3440 on the odo (yeah, I know, I know). I told the service manager about the brake dust and had the TSB all set for him, but he started asking me questions right off the bat...Squeel? Yes. Pedal Pulsing? No, but brakes grab at end of stop.

He looked at the rotors and said they would be replacing them and the pads. They had the fronts in stock, but as CB stated above, the rears are on national back order. I won't get my car back until Thursday . I'm already going through withdrawls.

[Jerrell]

Originally Posted by DZeckhausen

Just so you have an easier time articulating the problem to the dealer - there is no such thing as "soft" rotors. If you say this to him (assuming he has any knowledge of brakes), you will lose some credibility. Rotors that wear out quickly do this for a few possible reasons:

• The friction plates are thin. BMW is a good example of this. Many people claim BMW rotors are "soft" because Mercedes rotors last 50% longer. In fact, BMW rotors are lighter because they have a bigger air gap and thinner friction plates, allowing the car to handle better and improve convective cooling (vs Mercedes). BMW allows only 1.6mm of rotor wear, while Mercedes (with thicker friction plates) allows 2.4mm of rotor wear. There's your 50% difference! No difference in rotor hardness. It's the difference in new rotor thickness vs minimum allowable thickness.
  
  
• The pads are too aggressive. I believe this to be the case with the SRT8. The rotors are merely innocent victims. Many race pads, when run in their operating temperature range of 400 degrees (F) or more, are very rotor friendly. Those same race pads, when operated on the street at lower temperatures can be incredibly abrasive. Hawk Blue is the ultimate example of this. In my opinion, the SRT8 pads are behaving as if they are race pads being used on the street.
  
  
• Finally, excessive rotor wear can be caused by mechanical problems ranging from sticking calipers (not applicable to the fixed mount, 4-piston Brembos), to residual line pressure. Again, I do not believe that to be the case here at all.

Also, the pads are not "hard" or "soft". The abrasiveness of the pads depends on many factors, including size disparity between the particles used in the raw materials for the friction compound. I doubt this is the case, since DCX presumably went with a pad supplier who has sophisticated quality tools to ensure particle uniformity. So it probably has more to do with the design of the compound and the finished product's mix of abrasive vs adherent friction.

If this sounds like Greek, here's an excellent white paper that will give you some background to understand all this: http://stoptech.com/tech_info/wp_warped_brakedisk.shtml. Skip down to the section titled "The Nature of Braking Friction."

[Jerrell]

I am scheduled to take deliverly of a 300SRT8 soon. What should I do to ensure the best luck from this brake issue? Thanks.

[jgplayer318]

I know that I am in the elite company of the SRT8...however since our cars are in the same family, will us 300C owners have the same related brake problems. I have 11,000 miles on my car and have not experienced anything that you all are speaking of. I am nervous because I could be riding around at risk. The bottom line is, do I need to be going to the dealer this weekend? Any replies would be very helpful.

Thanks

[DZeckhausen]

Originally Posted by jgplayer318

I know that I am in the elite company of the SRT8...however since our cars are in the same family, will us 300C owners have the same related brake problems. I have 11,000 miles on my car and have not experienced anything that you all are speaking of. I am nervous because I could be riding around at risk. The bottom line is, do I need to be going to the dealer this weekend? Any replies would be very helpful.

If you read this thread carefully (or even skim it), it will become quite obvious that this problem only effects the SRT8 models with the OEM Brembo calipers. The root cause is the pad compound picked by DCX for the SRT8.

Your (non-SRT8) 300C has no such problems. The factory pads are low dust, low noise, and relatively rotor friendly. Your brakes are totally different than the SRT8 brakes. This does not affect you.

[CVC22348(b)(1)]

Got a call from the dealership. My rotors came overnight and my car is ready!

The service manager said the new rotors and pads are "revised" and shouldn't have the same issues again. I guess those SRT engineers figured out a fix after all. So, Jerrel, you might not have to worry about it - that much. Time will tell.

Now to give back the crappy Sebring convertible rental. What a POS!

[jgplayer318]

Originally Posted by DZeckhausen

If you read this thread carefully (or even skim it), it will become quite obvious that this problem only effects the SRT8 models with the OEM Brembo calipers. The root cause is the pad compound picked by DCX for the SRT8.

Your (non-SRT8) 300C has no such problems. The factory pads are low dust, low noise, and relatively rotor friendly. Your brakes are totally different than the SRT8 brakes. This does not affect you.

I thought that they were the same. Thanks for your help. I appreciate your reply.

[Jerrell]

Originally Posted by CVC22348(b)(1)

Got a call from the dealership. My rotors came overnight and my car is ready!

The service manager said the new rotors and pads are "revised" and shouldn't have the same issues again. I guess those SRT engineers figured out a fix after all. So, Jerrel, you might not have to worry about it - that much. Time will tell.

Now to give back the crappy Sebring convertible rental. What a POS!

[Jerrell]

Originally Posted by CVC22348(b)(1)

Got a call from the dealership. My rotors came overnight and my car is ready!

The service manager said the new rotors and pads are "revised" and shouldn't have the same issues again. I guess those SRT engineers figured out a fix after all. So, Jerrel, you might not have to worry about it - that much. Time will tell.

Now to give back the crappy Sebring convertible rental. What a POS!

Do you have any idea what "revised" indicates?