I've had poor results with cross-drilled rotors.
Perhaps it's the roadsalt and gravel in my climate.

My theory is that the abrasive road grime collects in the holes and gets trapped in the works instead of being swept away.
This trapped debris digs deep gouges in the rotor face and pads.
The chamfered holes may even encourage this to some extent. Many of the holes were completely clogged with debris. These ran about 1.5 years/22k miles to get this bad.

Looking at the pic, note that only the outer 1/4 inch or so of diameter (where there are no holes) is still in contact with the pads. The swept area that has holes has worn away so badly that there is no contact between pad and rotor.
The pads would otherwise have been about half-worn.

These are Brembo rotors with carbon-fibre pads on a modern Jeep. I'm currently running slotted rotors on both my Jeep and my MB for comparison.

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1986 300E 5-Speed 240k mi.

'00 E430 brake pads usages:

First front pads at 10k miles - Pagid, less dust than OE pads
Second front pads at 22k miles - ATE, much more dust than OE and Pagid
Third front pads + front rotors + first rear pads at 35k miles - front is Textar, rear is Pagid, very little dust and no noise

The reason that the pads does not last very long is the car has about 70% city driving and speed limit in Irvine - Newport Beach streets are mostly 45mph up to 55mph on some street, so that hard braking is the norm.
But buying parts online and have my indy shop do the work, I saved at least 50% compares with my local MB dealer.

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'00 E430 Brilliant Silver/Ash

I Have Had problems With Factory Cross drilled Rotors...
on My last Porsche Turbo the Front rotors cracked between the crossdrilled holes..I Have Also seen this on a Friends C32 With Factory Crossdrilled front brakes..

I have Found a Fix for this..I Sent the Rotors out to be treated ala cold dip treatment From Porterfield. Where they deep freeze the Rotor..It is said It makes the Brake Rotor last Up to Three times longer..I Did This on the porsche and Did Not have any more cracking problems..I Have also done this on the C32 brakes on my Coupe and Wagon..Time will tell on them!

aldedmon,

Thanks! Exactly what I was looking for!


Bud,

I'd be thrilled if I got 30k from one set of front pads! The pads are probably OEM as the PO had all work done at the dealer.

glenmore
1991 300CE

My 911 Turbo also did this, though the rotors and pads were usually shot by the time the cracking appeared. I did appreciate the drilling while driving the car in the wet, but not sure how much they contributed to dry braking performance. That said, the braking ability of that car was akin to throwing out an anchor. Max Perf tires were the ONLY ones up to the task of being bolted to those monster brakes.

I had a chance to drive a Turbo-look car once. It was non-turbo engine with the turbo chassis, complete with the monster brakes. Without the added go-juice of the turbo engine, that car had unreal braking power. Since it couldn't generate the high straight speeds, it never cooked the brakes at all when the braking point was reached. Nice combo.

My car could hurt you with the seatbelts when A-032R's were fitted.

BTW, the prices of the E500 brake job sound on the money for a dealer job. Be thankful you're not dealing with AMG-branded parts. Not for the faint of heart. My C36's rear axle alone was double the cost for both axles on the C230.

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John Shellenberg
1998 C230 "Black Betty" 240K

http://img31.exs.cx/img31/4050/tophat6.gif

[QUOTE]Originally posted by aldedmon
[B]My 3 coin rule
If your brake light is on and you have a lip whose thickness is no more than that a "Dime" - I might used them again.
"Pennys" - its about time to change them
"Nickel" - Regardless brake light or no hurry up and change em'


aldemon,

Here are the official thicknesses of the US coins:

Penny 1.57 mm
Nickel 1.98 mm
Dime 1.35 mm


You method looks spot on! Another post mentioned that for his rotors, original thickness was 25mm, replacement thickness was 23mm!!

glenmore
1991 300CE

Go with a good independent specializing in European cars. You'll save money and get better service in most cases. Build a relationship with this independent so you can trust their advice on future repairs.

The cost of rotors is reasonable, so you might as well replace them now along with new pads. Today's rotors just don't have much additional metal to remove. If they can be turned one more time, you'll probably need to replace the rotors again while your existing pads are still good. Then you'l have mismatched pads and rotors.

Replace the rotors now and forget about them until the next brake job. My 2 cents worth.

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Dave

1998 E320
2001 SLK320
2000 Lexus RX300