TTopJohn

I tend to agree that cross drilled and slotted are of little to no benefit, and don't have them on my car.

But bne think I can't figure out - if there is no benefit to cross drilling in a street application, why does Merceds put them on the front of the S-Class? Sure on a Porsche it could be a looks thing, but here it's not, the non sporty old dude who buys a base S430 isn't impressed by holes in the brakes, and probably can't even see that they are there through the 16" wheels. Surely the Benz engineers (who know more about brakes than me) wouldn't bother with the cross drilling if it were not of some benefit?

jRaskell

iTrader: (1)

Never EVER underestimate the power a marketing department or upper management can exert on an engineering team for any company that sells product to a consumer market.

Marketing departments in particular know only one thing. Perception IS reality to them. Physical and technical reality are absolutely irrelevant unless there are safety/legal concerns involved. What the customer wants, they'll get. What the marketing departments perceives the customer as potentially wanting, they'll most likely get. Just a fact of life.

Don't try to draw any conclusions from design decisions made for commercially available products. In most cases, the engineering departments have little say in the final product. They just do what they can within the confines of their given design specifications.

TTopJohn

True enough on a sports car - the Porsche buyer needs to see holes in his brakes to know that he's getting the best brakes money can buy. But for a base model Benz S430, the buyer doesn't know or care that the front brakes are cross drilled. The brakes are certainly not shown off, they are hidden behind thick spoke 16" wheels. So this isn't a marketing department decision, and I am certain that engineering departments have the most say in what goes into a system so essential to safe operation as brakes.

jRaskell

iTrader: (1)

I wouldn't presume to know what the average S430 buyer does and doesn't know or care about with regards to brake systems.

There's just far too many variables and unknowns involved in why a given manufacturer makes any particular design decision on a vehicle. Using any one of the decisions as a foundation for the performance abilities of any given design is transparent at best, especially when so much more accurate data provides contrary evidence, and automotive companies are known to be so much more sensitive to consumer perception than real world data. Perception really is reality, and the best of engineers are going to have a really hard time fighting that in almost any market. Perception sells cars more than anything else in this world, plain and simple.

Mercedes is a good example of that, actually. For your money, the entry level Mercedes (and I'm talking strictly your low end Mercedes here) is more expensive then many cars from other Manufacturers that offer just as much, if not more, across the board. Yet they sell, and in most cases they sell for no other reason than that badge on the hood that labels that car a Mercedes. A thin analogy perhaps, but a valid one nonetheless. Consumers are buying an image more than anything else, and that's perception over reality.

trackbird

iTrader: (4)

Like someone stated "cross drilled rotors work better everytime", many believe this and expect an expensive car to have "the latest" equipment (since they have no idea that this is not the latest nor the best), they put the rotors on there and the salesmen will sell them (I did sell cars at a Toyota/Mercedes dealership in 1995, Younger Motorcars in Hagerstown, MD). That really is the answer.

Cal

iTrader: (1)

I think the only usefull thing drilled rotors do is reduce unsprung weight. But this amount of weight is not noticeable unless the vehicle is a dual disk motorcycle or a bicycle. It's kind of like installing aluminum wheel studs; lots of disadvantages for little to no advantage.

glitch77

Alot of people think that when someone tells them the truth about drilled rotors that they are saying they are terrible things to buy (lets rule out cracking for a minute), when in actuality, all they want to tell you is that you wont be able to tell some sort of difference in braking by using them as everyone seems to think.

mitchntx

iTrader: (14)

That is true ... the differences are probably miniscual.

But, factor back in the cracking issues AND the fact that the marketing department jacks up the price because of the bling, then you start getting taken.

glitch77

This is true. A blank rotor costing $40 and a drilled rotor costing over $100 is highway robbery, but, you and I both know that you have to pay to play. I like the look of my iRotors alot, and am willing to replace them if they begin to crack (no problems yet[yet]), but I dont go around telling people to slap them on and go, because they are just a rotor, with some design flaws, nothing more.

If you want hardcore braking, get you a set of nice blank rotors, and put on some Hawk HP pads (or get ahold of trackbirds rotor-eaters). At $40 a pop for blanks at an autozone, you cant go wrong.

And about the benz having drilled rotors and how the driver would have no idea what they were, just look at the engine compartment of one. Tons of pretty plastic that the driver will never see if he never opens the hood. Its just something more to stick on the window at the dealer. And furthermore, those rotors *may* be cast with the holes in them, making them less crack-prone. Im sure they wouldnt just slap some junk rotors that had holes cut in em by uncle bob on the drill press on ANY benz, even the low-ends.

trackbird

iTrader: (4)

Oddly, I walk by a CLK430 every day on my way in to work and it has solid rotors on it?

TTopJohn

The lower end Benz's have solid rotors (well, AMG cars I think all have cross drilling - and there's your marketing exercise). Only on their biggest heaviest car (S class) to they crossdrill the fronts. And they do it on the solid citizen businessman non sporting S430, where the buyer is not impressed by holes in the brakes. Hence my argument that it can't be for marketing reasons, it's got to have some benefit. If it was for marketing, the CLK 430 sport, the C230 Sport, etc... would have cross drilling too.

hourang

iTrader: (6)

you cant sit there and tell me they are not going to know that they are cross drilled, im sure they go braggin yeah check out my mercedes, its got the holes in the brakes, and im sure like any other person they think they are better. im also sure the salesmen at the dealership sold them on that point also, hey even our base model has the upgraded brakes check em out. its like the people always asking if my car has the corvette motor in it, of course it does, they have always had the corvette motors in them.

TTopJohn

Yes I can. I know who these cars are marketed to. Anyone who would ever have a conversation about brakes in a social setting is not buying the base S430. That type of buyer is going to get a sport package S430, or get an entirely different car with sporting aspirations.

trackbird

iTrader: (4)

Well, they don't mysteriously work "better" for Mercedes. The rules still apply and physics is only mildly flexible. So, I can't say for sure why they did it, but I can tell you that it is no better/different than adding them to an F-body. Unless they are still using a pad that has outgassing problems (I doubt it), which is what the "holes" were there to correct for in the first place.

trackbird

iTrader: (4)

Maybe they are expecting a buyer to "cross shop" the Porsche dealership and figured they better "keep up with the jones's".

TTopJohn

Precisely. So if there is some benefit (whatever it may be) to having them on the S Class, then there could be some benefit to having them on an F body.

As far as cross shopping the porsche dealer keeping up with the Jones's, porsche doesn't have a car that competes with the S430. BMW (745), Jag(XJ8), and Lexus (LS430) do. And they don't have cross drilled rotors.

I agree that cross drilled rotors are not needed and usually a bad idea (cracking) for track work. And I don't run them on my car, I see rotors as a throwaway wear item so I buy the cheapest blanks I can find (tried KVR, now I'm on Aimco).

But I'm curious - if there might be some benefit (whatever it may be and however small it may be) to cross drilling in a street application, it's worth finding out.

hourang

iTrader: (6)

what if they cant afford the sport package but still want styling and performance? or are they cheaper?

TTopJohn

It's a relatively cheap option on the S430. But the main thing is the small engined S class is not a sporty car. If you're the kind of person who talks about brakes in public, and you're shopping Mercedes, you're not likely to even consider the 4.3 V8 powered S Class, you're much more likely to get the bigger 5.0 V8 in a lighter, sportier package for the same or less money - like the E500 Sedan or the CLK 500 Coupe.

Snootch

iTrader: (3)

I've read up about cracking on drilled rotors, and I saw these rotors that have a concave "smooth" countersunk hole that is supposed to alleviate cracking... What do you think of this? Webpage: http://www.raceshopper.com/sp_rotors.shtml
I also saw on this page that it was saying that cross-drilling allows gasses to escape created by the pad during braking. It was said in this thread that newer technology pads don't out-gas, making cross-drilling undesirable due to lower mass of the rotor, leading to faster heat build up, and cracking "checking" around the drilled holes. So do modern pads out-gas? I'm wondering if these rotors are worth getting, since i'm in the market for new ones.

Cal

iTrader: (1)

This is slightly off the subject, but there is a problem with some of those cheap rotors for the rear of an Fbody. Note that the stock rotor is a two piece unit with a thin steel hub. The hub section of many of the cheap rotors is a one-piece cast unit that is much thicker. This means that you have many fewer threads left sticking out to put the lug nuts on, and note that the ends of the stock studs aren't even threaded. You can easily end up with only 3 or 4 threads left actually going into the nuts. Yet another reason to upgrade to the extra long ARP studs.