[quote=" Dori Dori 1. Laser cut rotor hats aren't drilled.[/quote]Ah, fine, I'll give ya that one. But they might as well be drilled -- laser cutting produces a heat-affected-zone around the hole that weakens the surrounding metal -- just as bad, if not worse, than the stresses created by drilling a hole!

And the comment in your other message about stress risers still applies to aluminum hats that are drilled.

Quote »2. Do a search on the internet for cast-in-place holes. You'll find plenty of information and debates on them.[/quote]I'm talking about lug holes in brake rotor hats, not cast-in holes like Porsches use on their "cross-drilled' (cross-cast??) rotors. A quick google search revealed nothing of the former -- which, if you remember, is what this discussion is all about. If you have any links handy, please provide them so that we may all learn.

Quote »3. How much heat is needed to make a wheel bearing fail? You don't even know.[/quote]You're right, I don't know how much heat is needed. But I can tell you with 100% certainty that it's less than what's required to make the material in the hat of the brake rotor fail. Why? Physics -- and common sense.

Quote »5. Wow. One car uses them (the redrilled rotors). [/quote]You asked for examples, I gave you one that I thought of off the top of my head. You still haven't gotten back to me with your assignment.

My car has redrilled rotors too, but I've only taken them to the track twice. And no, they didn't fail. But I'm hardly a serious racer.

Quote » Auto-x no less. [/quote]I suggest you look up the difference between SCCA Solo-I and SCCA Solo-II. I'll even give you a link to help you out: http://www.scca.org .

Quote »6. THere are racers that use steel hats.[/quote]

Yes, I realize this -- is there anyone that uses steel hats if the series rules allow aluminum? I doubt it.

Quote » Also titanium hats.[/quote]Sweet. Titanium is cool. But it's not relevant to this discussion.

Quote »but if the bearing can reach those temps, and knowing the way heat conducts through the rotor, the rotor hat can surely see temps close to 1000degF.[/quote]I'm not so sure...1000 deg. F seems a little high to me. Granted, this is just me talking out of my *** in this instance. But remember, iron is a pretty poor thermal conductor -- and it gets worse at elevated temperatures.

Quote »With those temps, and the possible stress spot, cracking and warping are more likely to occur.[/quote]Sure, they're more likely. But if cracks in this region don't occur with non-redrilled 1-piece rotors, what makes you think that they would suddenly start happening in a rotor with only 3 extra holes on top of the original 5?

Asad

"I can easily heat up my brakes to 1400degF"

really? I'd love to see it. I mean, I do road atlanta quite often with guys running all sorts of odd brake conversions, like old 240Z's with toyota truck calipers(and redrilled rotors) who run for ober two hours and dont have problems...

yeah, the major issue with two peice rotors is for weight savings, not strength for sure. I mean, the bolts holding the hat to the rotor cant be more secure than a one peice unit at the stress points.

either way, its definately not asad vs the race community on this one. asad has made good, solid points, as have I, but now this is getting a bit over my 1.5 year ME education so I'll leave it to you guys to fight this out.

-chet

SCC Project Nissan Silvia

They did a 5-lug conversion and also used 2 piece rotors.

I'll quote some good parts in case you don't have time to read the whole thing:

Quote »Thanks in part to a lightweight aluminum mounting hat, the Brembo rotors are only 5 lbs heavier than the tiny stock rotor (16 lbs compared to 11 for the stock rotor). The enormous F50 caliper is only 1.1 lbs heavier than stock (Brembo is 10.1 lbs, stock is 9 lbs). To cope with the violent temperature swings and the different rate of thermal expansion between the cast iron rotor and the aluminum hat, the two are not rigidly mounted to each other. The rotor bolts to the hat through oval-shaped holes to allow the two pieces to expand different amounts when hot. The mounting bolts have some slack in them when tightened, and every other bolt uses a McLaren spring (so named because it first appeared on the McLaren F1) to keep the rotor and hat from rattling against each other.[/quote]So, as you can see, the two halves are not rigidly mounted together. The strength in stopping also relies on bolts used to hold the pieces together. I'd feel safer with a one-piece rotor over two-pieces loosely bolted together.

Quote »Doing it on the CheapThe lower cost (and lower performance) alternatives

The price of duplicating the modifications in this installment is admittedly high, but that's the cost of chasing Porsches. If you're only chasing Mustangs, here are the best ways to reduce the cost:

1: Skip the five-lug conversion.This not only saves the cost of hubs, spindles and ball joints, it also saves you from having to change wheels. The same brakes will fit if you have a machine shop re-drill the rotors with the appropriate 4 x 114.3mm bolt pattern. The Brembo brakes we used could easily be made with this four-lug pattern, but Brembo won't produce them unless it gets enough requests. Luckily, 10 requests will do the job. Brembo's phone number to is to the right.[/quote]SCC even tells you to go ahead and have 'em re-drilled if you don't want to do the 5-lug!:thinker

And if you still don't like the re-drilling idea Dori Dori, then either do the 5-lug conversion, or get at least 10 peeps together and Brembo will make you some!:D

Oh man, hate to bump such an old thread, but I haven't been around in a while b/c of a crashed computer and I didn't want to give the impression that I ran away.

Asad, I really have no interest in fighting with you on brakes anymore. My reasons for not liking redrilled rotors are real. While some things may seem negligable to you or on paper, it's my *** on the line, and I'd rather not take my chances. I don't like redrilling cast iron...you do. Hooray.

I would like to point out though, that Solo1 racing, while not Auto-x, is pretty damn close. When I say racing, I mean real racing...30-60min at a time of hard, full-on racing. Not solo sprints.

Exar-Kun, yes, it's easy to get a mono block cast iron rotor to those temps or close to it.

SR20DET240, I know all about floating hat design on 2 peice rotors. We aren't even talking about the rigidity of the hat to rotor plate anyway...I am talking about stress points on the hat (where the lug holes are drilled and re-drilled) caused by drilling cast iron.

And yes, I am well aware of SCC's 'cheap route' reccomendations. But notice that they didn't do it on their car. They're chasing Porsches...and I may do the same.

So you're gonna spend 3 grand on brakes to avoid needless holes? Really?

For that money you could buy a 300zxtt brake and 5 spoke conversion, and assuming you keep the rear size rotors, you could test out different master cylinders, work out all modulation problems and have a set of "sorted" brakes and have enough left over for coilovers and sorting them too.

But hey, if beating a Porshe on track day is what you want to do....

[quote=" Dori Dori Asad, I really have no interest in fighting with you on brakes anymore. [/quote]Is that because you know your arguments hold no water?

Quote »My reasons for not liking redrilled rotors are real. While some things may seem negligable to you or on paper, it's my *** on the line, and I'd rather not take my chances.[/quote]If that's the case, why use a rotor with any lug holes? Just switch to a single center lug setup. Oh wait, that center hole causes too much stress on the metal -- you should just use a hat without ANY holes, period, and have wheels that are attached to the hub through the use of superconducting magnets! :rolleyes

Quote »I am talking about stress points on the hat (where the lug holes are drilled and re-drilled) caused by drilling cast iron.[/quote]And yet you ignore the points I made regarding the SAME stresses occuring in an aluminum hat!

Oh, one other thing: Baer Brakes (who I'm sure you would agree is a reputable company) has at least one kit that uses dual-drilled 1-piece rotors -- their Miata kit:



You can infer from that what you will (although given the trend we've seen so far, your inference will probably be wrong...)

Asad

GO ASAD!!!

DD, is the amount of money spent on your car proportional to how fast it goes, or in this case, how fast it stops?

Now you are pissing me off b/c you are straight up wrong. I'm not going to get into an arguement with you on the differences casting and forging...but saying that you get the same types of stress points when drilling forged billet aluminum that you do with drilling cast iron is dumb. I think that you just can't give this a rest b/c you know you are wrong and you are trying to save face or something. You've already admitted that you were wrong from the begining. Remember, my arguements are that:1. The rotor becomes weaker when redrilled.I am right. Negligibly weaker or not, I am right.

2. We then went into discussion on how all rotor hats were drilled. You were wrong...again.

Now you want to say that the same stresses that occur in drilling a cast iron rotor occur when drilling a forged peice of billet aluminum? Bring it, cause you'll get proved wrong again. Search the magic words 'stress ponts' and 'drilling cast iron' to find your answers before fighting with me again.

Here's the bottom line. Your reason for thinking it's OK to redrill a cast iron rotor is b/c of a simple math equation you used to prove that (in a perfect world where stress points and casting imperfections don't take place and heat is not a factor) surface strength is only 'negligibly' reduced. Hoo-fuqing-ray...your opinion differs from mine. Like I said, negligibly or not, when I'm behind the wheel, I don't want any part of my car to be made into a weaker part than stock.

I can admit it and move on when I say something that is wrong. Like when I thought that lug holes were cast in place...I was just confusing cast in place holes in rotor faces and forged (or laser cut) rotor hats from 2 peice rotors. I'm not fighting about that anymore...:thinker

And SR20DET240, S T F U. It's obvious that you don't know what the hell we are talking about. That's why you started comparing rigidity of floating hat design rotors (where the hat meets the rotor face) to single peice rotors.:rolleyes

And for what it's worth, I'm not buying Brembo brakes or chasing Porsches. I was just trying to kill the arguement. To be honest, my plans were to do a full 300zx brake upgrade (front and rear) w/ 5-lug conversion. So, I'm not spending $3000. I'm actually going to only spend a couple hundred dollars more than the redrilled front kits (for front and rear)...so really, I'm spending less b/c I'll also have the rears done w/ a parking brake. My main reason for a 5-lug conversion was wheels...

Oh, and as for that Baer kit...that's their sport kit. It's not for racing... I'm sure it's fine for the street just like the redrilled s13 kits. I never disputed that.

Looks like someone is losing their temper.

If your main reason for converting is just wheel preference, why do you keep talking about racing tolerances? :pface

:crazy

[quote=" Dori Dori 2. We then went into discussion on how all rotor hats were drilled. You were wrong...again.[/quote]In my mind, for the purposes of this discussion, laser cutting is equivalent to drilling.

Quote »Now you want to say that the same stresses that occur in drilling a cast iron rotor occur when drilling a forged peice of billet aluminum? Bring it, cause you'll get proved wrong again. Search the magic words 'stress ponts' and 'drilling cast iron' to find your answers before fighting with me again.[/quote]I know that drilling into cast iron produces stress risers. You seem to be implying that drilling into a piece of forged aluminum doesn't produce stress risers -- preposterous!

Quote »Like I said, negligibly or not, when I'm behind the wheel, I don't want any part of my car to be made into a weaker part than stock. [/quote]Then you should stick with 4-lug brakes -- that extra hole makes the 300ZX rotor's hat face weaker than with the stock 4-lug brakes. :rolleyes

Quote »I can admit it and move on when I say something that is wrong. [/quote]So can I. But you haven't convinced me I'm wrong. Without any real testing to back up either of our claims, neither of us can claim we're right or wrong. I'm just trying to impress upon you that your concerns are unfounded.

Asad

asad wrote:In my mind, for the purposes of this discussion, laser cutting is equivalent to drilling.

I don't care what your mind thinks. You were wrong.:nopity

asad wrote:I know that drilling into cast iron produces stress risers. You seem to be implying that drilling into a piece of forged aluminum doesn't produce stress risers -- preposterous!

:nono I never said it doesn't. You said that "And yet you ignore the points I made regarding the SAME stresses occuring in an aluminum hat"...that is not true (since I was talking about forged aluminum, I must assume that you were as well). We all know the forging process allows for a refined grain structure and imporved physical properties of the metal. Actually, with proper design, the grain flow can be oriented in the direction of the principal stress that will occur during actual use (I know this doesn't really matter for our discussion, but I thought it was cool, so its just an FYI). One of the causes of stress risers by drilling cast iron is because of it's poor grain flow...something forged metal doesn't suffer from. Also, there are no internal gas pockets or voids in forged metal...something that's present in cast metals; which again, increases the likelyhood of stress risers when drilling. Really, the only stress risers found in forged metals are caused by sharp points...not drilling. Are you trying to tell me that forged metals have the same structural integrity as cast metals! Preposterous!:rolleyes

asad wrote:Then you should stick with 4-lug brakes -- that extra hole makes the 300ZX rotor's hat face weaker than with the stock 4-lug brakes. :rolleyes

Please, I'm getting tired of your childish comments.:thumbd In the same light, I can ask you 'since the extra holes only make the rotor 'negligibly weaker', why don't you drill 4 or 5 more holes into it?' 'That way, you'd have an ultra-light-weight-ghetto-rigged-rotor'.:rolleyes

asad wrote:So can I. But you haven't convinced me I'm wrong. Without any real testing to back up either of our claims, neither of us can claim we're right or wrong. I'm just trying to impress upon you that your concerns are unfounded.

I'm still trying to figure out what you are 'right' about. Right now we are just going around in circles. I am right and that's the bottom line. Whether or not you feel I am being paranoid with my concerns or not...my reasons for disliking re-drilled cast iron rotors are real...even if they are only 1/10000% weaker, I don't care. What, are you worried about me? Are you afraid that I may spend an extra couple hundred dollars on something that I don't need?:rolleyes Sheesh, for the record, I would have left this alone, but you insisted on posting that childish remark accusing me of being a copout. I am still willing though...

this is starting to sound a lot like:Kid1: IM right!kid2: no, Im right!kid1: NO! IM RIGHT!kid2: NO! IM RIGHTER!

etc, etc.

tell you what, lets get a rotor, of the same type(one redirlled, on not..or something like that.), and test them in a lab, or even better CALL BREMBO. **** I might do that myself. I'll ask them why they use 2-peice rotors, and if they know how holes affect stuff! hows that? then we'll know for sure.-chet

I don't know how much stress is actually put on those holes anyway. Remember that the rotor is sandwiched to the hub by the wheel. When they are bolted together it kind of acts like one unit taking the stress. I mean there is some serious friction between the face of the rotor and the face of the wheel touching the rotor.

I'm not sure if you get what I'm saying because its kind of hard to explain. What I'm trying to say is that the rotor is held on by the wheel and I thought that, in turn, the wheel would take some braking force and transfer it to the lugs rather than the rotor holes transferring all of it to the lugs.

Just thought that might play a part. Gotta watch what I say or I might be accused of being an idiot by Double-D.

The main reasons that they (Brembo) use aluminum for their hats is for weight savings and heat transfer.

I know iron is 'stronger' than aluminum. I'm not fighting about that... But have you ever seen a cross drilled rotor, especially mono-block cast iron (or even slotted) after a few races (or track events). There are hairline cracks all over the face of the rotor...especially next to the holes or slots. Why, b/c of the stress risers found in cast iron (especially drilled) combined with extreme amounts of heat. Now why on earth would you want to drill more unecessary holes (causing more stress risers) onto a peice of cast iron that already has enough stress risers from the casting process (internal gas pockets and voids) at such an important place like the rotor hat! Those holes are big too! It's just not worth the risk to me...it's the same reason why I won't buy crossdrilled rotors. Like it or not, it's my reason.

OMG, you're still fighting? give it up already....

Dori Dori - You obviously aren’t gonna change your mind no matter how many people disagree and since they have the majority on their side (as well as one of the most respected posters on these type of forums - asad) they certainly aren’t gonna change their minds....

Be the bigger man and walk away.

I can't believe I've missed this thread. That's the funiest debate I've seen yet. I've decided to go 8lug on my car, DD, you think that's good or bad? Don't reply, I'm joking, just amazed that you're so worked up over a point of OPINION. You don't like drilled rotors, cool, other people do. Live with it, no one is making you drill your rotors are they?