:yesnod: ...

 

Right on Ryan, the sacrafice was the rotors to produce high end braking by cross drilling. Today not necessary, solid rotors even though not as pretty are making a come back I think.

Tripp

 

Yeah, but the slotted ones look cool also.. I dont think they are as prone to cracking, but I dont really know much about them.
Someone else made a reference to seeing the cracks, I dont think that you can always see the cracks, many are very fine, and go outward from the radius of the holes. Ask Baer, theyll tell you its pretty only. Now, if I could just get some of those carbon-ceramic brakes! :eek: :D :cheers:


[Modified by rrobert22, 5:43 PM 7/7/2002]

 

I read that somewhere, but don't remember where. Something about where drilling the holes after the original casting causes micro fractures, just like when using a glass cutter on glass. Then heating and cooling would cause the micro fractures to expand and increase in size.

But making the holes a part of the mold where th eholes are created during the poured metal casting process didn't have the problem.




[Modified by Mike Mercury, 7:11 PM 7/7/2002]

 

Veeerry Intereeesting (in my mad scientist voice) :yesnod:

 

I would like to know more about this process because I really really like the look ...... :yesnod: .... :cool:

 

evil 1, mov-it offers this kind of rotors you are interrested in. They supply as well the Porsche 996 stock brakes (4piston caliper, monobloc build, two piece rotors with black center made from aluminium, cast with holes). In their programm is as well a ceramic brake system (the best money can buy today !)

The site is in english.
http://www.movit.de

Jochen

 

Thanks Jochen........ :cheers:


Tripp

 

I agree for racing applications, the stock rotors are hard to beat for the price. Rotors are a wear item that you will always be replacing so might as well go with the cheapest models that work. Having said this, I love my Eradispeeds.

 

:lol: :lol:

 

I had my factory stock rotors cross-drilled for looks two and a half years ago when I first bought my 2000. I am now at 13000 miles and have no cracks. My friend cross-drilled them carefully not drilling the veins. IT LOOKS AWESOME! I would suggest it for shows but not for serious racing.

 

Drilling or cutting slots into any metal which has originally been cast produces "stress risers". SRs are created by rough surfaces on machined edges. Untreated SRs become the originating point for cracks which are produced in the heat cycling process. All brake rotors develop these cracks or heat checks over time. Drilling holes or machining slots just multiplies the source of the SRs which makes such rotors more prone to developing serious cracks. Slots are a further detriment because they weaken the base metal.

How do you avoid SRs in drilled rotors? By either casting the holes ( as Porsche does) or peening the ground areas. So if you are patient, you can sit the with a hammer and ball bearing and manually peen every hole that was drilled.

Racers are in a hurry and have learned long ago not to waste their money or time on drilled rotors. The stockers with a cryo treatment do just fine for most racing folks.

BTW, just because rotors don't crack on an autobahn driven car doesn't mean they'll hold up on the racetrack. In practice, autobahn conditions are not much tougher than aggressive interstate driving in the US. Neither has anything to do with track racing, where you put your brakes through a full day of repeated heat-cycling torture.

So, if you want to look pretty, get the x-drilled rotors. If you want to stop fast, spend the money on good pads (PFC), a good brake fluid (Motul 600F), Speedbleeders, and sticky tires.

Hope that helped.

 

"peening" ????

that sounds like something my mother told me to never - ever do. Oh wait... that
was something else :bb

:)

 

"In practice, autobahn conditions are not much tougher than aggressive interstate driving in the US"

Sorry, but i never drove 175 MPh in the states.

If you ever raced against a Porsche 911 Turbo or a Maserati 3200 on a german autobahn, you will make up your mind about that!

Getting the C5 up to 175 MPh braking down to 60 MPH because a truck pulled out a few hundred feet in front of you and now getting up again to a speed of over 150 MPH . . . And this on the Highway from Munich to Frankfurt (approx. 2-3 Hours) and this many times . . . And you tell me that this is like "aggressive interstate driving ".

I have been in the states many many times and never got only close to such a driving condition.

Sorry, but thats just not true. Everybody who ever drove serious FAST on Autobahn can confirm that this is a hell of a job for your brakes !

If you ever come to germany, visit me :D you ll see

Jochen




[Modified by Jochen, 2:40 PM 7/8/2002]

 

Jochen,

I think we are talking about 2 different levels of stress on brakes.
Take a look at: http://www.gingermanraceway.com/specs.html
There are 3 main straights here. Speeds in a C5 reach about 110, 105, and 95 MPH in these straights and about 80 to 60 in other sections. At the end of all these straights are tight, to very tight, corners that require you to be in the 20 to 40 MPH area. This is constant and unrelenting, and to have good times you need to go in deep and brake very very hard.
I was in Germany, quite frequently, at our Frankfurt office and would drive a Mercedes 560 SEC often on trips, particularly to Geneva and our Belgium offices. While a 560 certainly isn't a C5 I did see a lot of the autobahns from the left lane. <G>

The brake stress on a track is much harder. The brakes get no time to cool down. (Can you imagine how much cooling you have when you get back up to speed on the autobahn?)
On this typical road course you are full on the brakes 10 times in 1.8 miles! Now take that braking effort and multipy by 10 to 20 laps...

There is a saying when you come off the track. "If the brakes aren't smoking you aren't driving!"




[Modified by Richin Chicago, 11:41 PM 7/8/2002]

 

Good comments, thanks for the info guys, I was thinking about cross drilled, but now, it is not a priority.

 

I think the point made in an earlier post says it all, cross drilled rotors that are cast have a much less change of stress cracking then post drilling.

 

Actually Jochen, I just got back from Germany last week, where we picked up my father's new M5 on euro delivery (nice car) in Munchen. I had plenty of seat time in the car on the A8 and A9. We had hoped to get some serious speed out of the car, but between traffic, detours, and restricted speed zones, I was lucky to hit the car's speed limiter (250kph) only three times during the entire 10 days. I measured the trip times on the car's computer and could do no better than 170kph and that was on a short trip. Frankly, I was disappointed - I had expected some serious autobahn blasting, but the conditions did not seem to permit that. Traffic in particular was extremely heavy and there were quite a few jams. In the few unrestricted (speed) zones, most of the traffic was moving far more slowly than we were, and the only vehicles that passed me were motorcycles and one guy in a 996 Turbo with temp plates who blew buy and almost wadded himself into a truck two seconds later. Undoubtedly an American. On average, I would say traffic was moving at about 130-160kph in the unrestricted sections which is frankly not much greater than our speeds out west. I averaged 125mph (200kph) on my last trip from LA-Vegas and traffic moves at 130kph on average on LA freeways. None of this is surprising given the price of fuel in Europe and the fact that financial responsibility for accidents in Germany rises exponentially when those occur at speeds exceeding the recommended 130kph (80mph) - or so we were told repeatedly by our German friends. Also, the German police are everywhere and don't kid around with speed. Traffic fines are very expensive when handed out, just as they would be here if you get popped. We were also informed that Germany has a points system, just like here. There, as here, going fast costs money. That, at any rate, is the logic behind my "in practice" comment.

In any case, even fast Autobahn driving is not at all the same as race driving when it comes to stressing brakes, tires, and engines. There is just nothing like it to wear out parts. Jochen, come see us in the US and hang out with us at our race tracks. There's nothing like it, believe me. It's a great place to exercise your Vette to its fully potential. Maybe you can pick up your next Vette museum delivery and play with it here a bit before shipping it over.

In any case, southern Bayern is beautiful...Berchtesgaden and the Konigsee in particular were charming. :seeya

 

Hey Marc,

i am really happy to hear that you had the chance of "testing" the german autobahn. Unfortunattely you are right in most of your points - Traffic is terrible, at least in the rush hour periods. And it is true that sometimes we have traffic jams as long as 50 (!!!) miles. Especially during the holiday seasons.
Its an important point to know when you have to drive on what autobahn (at what time of the day and weekday). When you drove the A9 from Munich to nurnberg, you probably saw the "potential" of speed on this 100 miles straight autobahn . . . On this street i opened her up several times over 180 MPH.
I had my best runs (mentioned above with 996 and 3200) on A8 from Munich to Stuttgart. When i visit my people close to Frankfurt, i allways choose a time to get the chance to get my car up to the maximum.

I never doubt that race track miles are much more stress on ANY component of the car than street miles. This is no question. And i know what fun it is to watch the C5 on the racetrack (i did several times, one time with some friends from Miami on Moroso Motorsport park, West Palm Beach last year June). However if i will have a vacation in the future in california . . . be shure i will give you a call :)

What i want to say with my first post in this thread is that my experiences with the drilled rotors are much better than most of the people write here. And that my stock, not drilled had some terrible cracks (even in the back). I swear, i could stick my fingernail in one of this cracks ! When i compare now the performance of the stock against drilled BAERS (which i know are basically stock too, but treated and machined) i have to say that the BAERS outperfomed the stocks without any doubt. Thats my personal experience with this rotors.

Anyway, the idea with the Museum delivery is a great idea . . . :cool:

Maybe we can meet next year in Nashville. My wife and me will definitally arrange our next vacation so to be there . . .

:seeya
Jochen

 

Come to the A62, A1, and A48 on weekend mornings and you will have a big smile, and no warped brakes because traffic is very light. Even in the afternoon traffic is still light.