Some SRT8 photos from the SEMA show in Las Vegas

[DZeckhausen]

Originally Posted by davequick

Other than convention - what is the main purpose that 3 or 9 is optimal?

It minimizes the impact of wheel bearing deflection on the calipers. In other words, a caliper at 12:00 is more likely to suffer from pad knockback than a caliper at 3:00 following a series of turns with high lateral loads. See: http://www.stoptech.com/whitepapers/knockback.htm

[DZeckhausen]

Originally Posted by DZeckhausen

I realize you're teasing me. But to clarify. I said the SRT8 rear caliper is approximatly in the same location (perhaps 15 degrees CCW) of the 300C rear caliper. I didn't say that EITHER caliper was in the ideal 3:00 or 9:00 position.

I'm putting the rear StopTech brake kit on my 300C right after I eat lunch. I'll take some photos to see if it's obvious why they oriented the calipers the way they did.

Well, I now understand why the SRT-8 and the "ordinary" 300C have the rear calipers located in the leading position. If they were clocked to the trailing position, they would interfere with the lower control arm as well as the end link for the rear swaybar. This photo should make it more clear. This is the right rear corner of my car:

[DZeckhausen]

The rest of the photos may be found in the Brake forum at the following thread: http://300cforums.com/showthread.php?t=2092&page=3

[davequick]

Originally Posted by DZeckhausen

It minimizes the impact of wheel bearing deflection on the calipers. In other words, a caliper at 12:00 is more likely to suffer from pad knockback than a caliper at 3:00 following a series of turns with high lateral loads. See: http://www.stoptech.com/whitepapers/knockback.htm

Thanks for the pointer to an explination.

It makses sense to me on race cars but not production cars, but I'm not involved with a racing effort personally and have less than zero actual wrench time myself...

Thinking throug the problem of braking during cornering which seems to be the only time that wheel bearing deflection would occur based on the sketches at the URL you provide - if you were within proper tolerance for alignment on your caliper and pad setup) the car (i'm thinking SRT8 standard with ESP) will sense out of proportion wheelspin for input steering control and pulse that brake due to the Bosch 8.0 software inthe brake controller - the pulsing is equivalent to letting off the brake and reapplying 150 times per second. At least if the ESP is equivalent to the current Mercedes parts bin in 2005 Mercedes cars. Even with ESP "deactivated" it is stil on - just at about 20% the effectiveness as when it is fully active, again - if equivalent to current ESP in Mercedes.

Does this type of electrronic intervention help mitigate the conventional wisdom of 3 o'clock on a road going car with a brain? I mean obviously most race classes likley ban this type of electronics and I can see the 3 o'clock as a necessity for them... but what's your opinion - does the electronic smarts in a modern car like an SRT8 with ESP negate the concern of piston knockback for fixed caliper setups?

Thanks in advance for the education. :-)

-dq

[DZeckhausen]

Originally Posted by davequick

Does this type of electrronic intervention help mitigate the conventional wisdom of 3 o'clock on a road going car with a brain? I mean obviously most race classes likley ban this type of electronics and I can see the 3 o'clock as a necessity for them... but what's your opinion - does the electronic smarts in a modern car like an SRT8 with ESP negate the concern of piston knockback for fixed caliper setups?

Typically, one would disable this type of electronic intervention when tracking a car. Otherwise, the conservative software would be cutting power to the engine and reducing slip angles to the point that your lap times would be seriously compromised.

Keep in mind that this knockback issue ONLY occurs when you put sticky tires on the car and drive VERY hard on the race track. That's when weakness of the wheel bearing design becomes apparent. This is not something that is going to happen on the street.

[indyCoder]

Man those ST look good. I've had 22's for about 4,000 miles, no problems. I’m with you on upping the brake. I have to decide if I’m keeping the C or getting an SRT.