is a 4 lug to 5 reasonable?

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Dori Dori
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It has to do with how that machined peice of aluminum was made. It's not a 'cast'. It's a bent up piece of aluminum.

As for machining anything else...that's not an issue. I never disputed what can or cannot be machined. I'm talking about aluminum rotor hats. You could machine plastic too...but what does that matter. It has nothing to do with this discussion.

The hat of the rotor sees alot of heat so IMO a redrilled cast iron rotor can't be too good. Again, it's just my opinion...try to prove to me that a redrilled rotor is just as safe as a once drilled rotor. All logic says otherwise.


asad
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[quote=" Dori Dori It's a bent up piece of aluminum.[/quote]Yes, a forged hat would be. But a forged hat will have the grain pattern running radially on the face of the rotor -- and when you drill the holes, you're going to drill perpendicular to the grain direction, which results in "end grain" terminating on the holes, which are weaker than the surrounding area.

Quote »The hat of the rotor sees alot of heat so IMO a redrilled cast iron rotor can't be too good.[/quote]The problem is you're basing your arguments on opinion. Here's another fact for you:

Iron melts at about 1800K (2780 deg. F). Aluminum melts at about 900K (1160 deg. F). So which would be better at high temperatures? I would put a redrilled cast iron rotor hat up against a forged aluminum rotor hat (in terms of strength at a given temperature) any day of the week -- the redrilled cast iron hat will win every time, hands down.

Quote »try to prove to me that a redrilled rotor is just as safe as a once drilled rotor. All logic says otherwise. [/quote]No -- your opinion says otherwise. I have materials physics on my side.

Asad

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Oh, and just to expand upon the fact that the material removed is a small fraction of the total material in the face of the hat...

The face of the hat has a diameter of about 6" (I measured it at 6.082", but 6" is good enough), and the lug holes are about 0.5" (again, they're actually closer to 12mm, but 0.5" is good enough) . Using these numbers, the total surface area of the face, with the 5 original lug holes removed, is 27.3 in^2 .

If you remove 3 additional 0.5" diameter holes (which is all that's required to convert to 4x114.3), the total surface area drops to 26.7 in^2. A whopping 2.2% change!

Now, you will not find a single brake system in existence on the planet that has a safety margin of only an additional 2% on the strength of the components used. I'd say 100% safety margin is the bare minimum, and it's likely to be much more than that.

On this basis alone one can see that, as I said before, the strength change from redrilling rotors is negligible -- indeed, absolutely, utterly, and completely negligible.

I would even go so far as to say that multiple lug pattern holes in an aluminum hat poses no safety or strength concerns. Don't believe me? Coleman Racing offers cast aluminum hats with a dual bolt pattern (5x4.75 and 5x4.5) -- and those hats have 2 more lug holes than a redrilled 5-lug rotor!

Asad

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Quote »The hat of the rotor sees alot of heat so IMO a redrilled cast iron rotor can't be too good[/quote]Hmm, so yeah, the cast iron rotor faces that see even MORE heat than the hat can't be too good either...

Asad

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Exar-Kun
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"The hat of the rotor sees alot of heat so IMO a redrilled cast iron rotor can't be too good. Again, it's just my opinion...try to prove to me that a redrilled rotor is just as safe as a once drilled rotor. All logic says otherwise"

we just did. and logic proved it for us, cast iron, like asad said, has a far higher heat tollerance than alluminum. thusly, any material removed form a heated area would be, if anything, LESS signifigant on a cast iron rotor than a aluuminum rotor "hat".

also, the majority of heat isnt on the "hat" of the rotor, its on the face, thusly negating yor argument completely.

-chet

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Dori Dori
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asad-Yes, iron can withstand more heat but due to the design of an aluminum rotor hat and the fact that it is aluminum, the heat dissipates faster. It's also paper thin. That's why metals like copper and aluminum are used as heatsinks...not iron. That's why your calculations have nothing to do with the real world. You are only taking one thing into consideration and thats surface space.

BTW, why did you quote me 2x.?:confused:

Exar-Kun- rotor hats do see a lot of heat. That is why ustcc race cars w/ modified stock brakes usually go through wheel bearings every race and why other components become thermally stressed. I still stand by what I believe. Redrilled rotors are not for me. I think they are stupid. I'd rather spend a couple hundred bucks more to get something that is safer and stronger. See, I'm the kind of guy that actually breaks in his new car just so it may last 1000 miles longer. It's just me. Get over it.

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Good point there on some rotors having dual 5 lug patterns, if that is good then having 2 less holes has got to be "better"

I am putting Z brakes on my car so I obviously don't care about the three extra holes. Besides the brakes are stopping a car that is dang near 1000 lbs lighter...

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Dori Dori wrote:asad-Yes, iron can withstand more heat but due to the design of an aluminum rotor hat and the fact that it is aluminum, the heat dissipates faster.
Ah, but you're forgetting that iron has a lower thermal conductivity than aluminum. So given that the cross-section for conductive heat transfer into the hat is extremely small (probably a factor of a few hundred less than the cross sections for heat loss through convective and radiative cooling. So the amount of heat that gets into the hat is very small in the first place, compared to the amount of heat that the rotor friction surfaces see -- and it will be nowhere near the amount of heat needed to raise the temperature of the hat to a point where the material weakens. Temperature in this argument is a non-factor (well I suppose it actually goes against your argument for aluminum hats, due to aluminum's higher thermal conductivity, which will transfer the heat more effectively to the face of the hat)

Quote »That's why your calculations have nothing to do with the real world. You are only taking one thing into consideration and thats surface space. [/quote]I didn't take the thermal effect into consideration because I already claimed that the heat would be a negligible factor in the strength.

And believe it or not, the "filled" surface area does give an indication of the strength of that area -- and in this case the change is negligible compared to the safety margins designed in to brake components in the first place.

Quote »BTW, why did you quote me 2x.?:confused: [/quote]Ah, I quoted that later, after the first reply.

Quote »rotor hats do see a lot of heat. That is why ustcc race cars w/ modified stock brakes usually go through wheel bearings every race and why other components become thermally stressed. [/quote]That's all well and good, but the amount of heat needed to stress a wheel bearing and the amount of heat needed to affect the strength of a flat piece of cast iron (the rotor hat) are VERY VERY different.

Quote »I still stand by what I believe. [/quote]Again, the problem is that you're "believing" rather than listening.

It's fine for you to prefer to have something that you believe is stronger (BTW, I still stand by my statement that a redrilled cast iron hat is stronger than an equivalent single-drilled aluminum hat).

But don't spread misinformation, and don't project your illogical biases onto others.

Asad

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Dori Dori
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So you are telling me that a redrilled cast iron rotor will make for a better/stonger rotor than a full on 2 peice aluminum hat rotor? Man, you need to talk to the people at brembo, willwood, stoptech, and any other major race brake manufacturer. They have it all wrong. I'll do it. I'll stop believing all those brake manufacturing swine. They've been fooling the racing community for years.

Asad, do you think we could go into business together redrilling monoblock iron rotors for race cars? Once you spread the truth about them and clear up all the lies, I bet we could become rich!

Email me!

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asad, havnt i tought u anything? : )

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Dori Dori
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I don't care where he graduated from. It boils down to this:

The entire race car community vs. asad

You pick your side.

asad
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[quote=" Dori Dori So you are telling me that a redrilled cast iron rotor will make for a better/stonger rotor than a full on 2 peice aluminum hat rotor?[/quote]Stronger, absolutely. Lighter, not a chance in hell. Don't confuse the issues at hand. 2-piece rotors are not two pieces for strength reasons -- they are two pieces for weight savings and to allow for thermal expansion of the disc, which experiences a lot of cyclic thermal stress compared to the hat.

The only thing of concern in this discussion is strength.

I don't need to call Brembo or Wilwood because I'm discussing facts. Perhaps YOU should call up Brembo, Wilwood, etc and ask them if an iron rotor hat is stronger than aluminum. I already know the answer, but it seems you are impervious to logic and will only change your opinion if some "reputable" source tells you.

Asad

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I H8 UR DSM wrote:asad, hasnt princeton thought u anything? : )


Oy, please don't bring my education into it. I prefer my arguments to stand on their own merit rather than having a big "name" attached. FYI Dori Dori, I didn't graduate from Princeton.

Asad

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done

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Dori Dori wrote:I don't care where he graduated from. It boils down to this:

The entire race car community vs. asad

You pick your side.


k, im on Asad's side.

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Dori Dori
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Heat is also a concern. What happens to a hot iron rotor? It warps. What happens to a hot iron rotor with holes? It cracks. It's the same reason why they are beginning to cast holes in rotors instead of drilling them.

In a 2 peice aluminum hat rotor, the hat doesn't see anywhere near as much heat as the iron one does. Sure, when they are both exosed to the same conditions, the iron will be stronger...but because of the design of a 2 peice rotor, the aluminum won't see anywhere near as much stress/heat as the iron one.

Maybe I should have specified, but I thought it would be clear...in a race brake application, an aluminum rotor hat will hold up better than a cast iron one...especially a redrilled cast iron rotor. Are you disputing this or are you disputing the strength of metals exposed to lab controlled testing?

asad
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Dori Dori wrote:The entire race car community vs. asad


If you call one of the brake manufacturers, you'll find that it's actually you vs. the entire race car community and myself.

Remember -- we're only talking about strength!

Asad

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Dori Dori
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It's funny. My whole arquement in the beginning was that more holes make the rotor weaker and that not all rotors where drilled.

You proved to yourself that more holes do make the rotor weaker and you already knew that not all rotors are drilled.

So why did you fight with me? From the second you came on this board, you quoted almost everything that I said from that day. What gives? You don't like my name or something?

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Dori Dori
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asad wrote:Remember -- we're only talking about strength!

Asad


You keep saying that but strength is affected by heat! Like I said, your calculations mean nothing because it isn't the real world!

Real world. Brakes get hot...real hot. They also cool down fast...real fast. Do those extreme conditions not affect the metal? Hint: they do.

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Dori Dori wrote:Heat is also a concern. What happens to a hot iron rotor? It warps. What happens to a hot iron rotor with holes? It cracks. It's the same reason why they are beginning to cast holes in rotors instead of drilling them.
You're not listening. The face of the rotor HAT doesn't get to the same temperature as the friction surface! The face of the rotor HAT does not get to a temperature where the strength of the iron in the face of the HAT of the rotor is a concern!

Quote »Maybe I should have specified, but I thought it would be clear...in a race brake application, an aluminum rotor hat will hold up better than a cast iron one...especially a redrilled cast iron rotor.[/quote]The issue here is WHERE a failure would occur. I have seen reports and images of 1-pc iron rotor failures -- but these are always at the point where the hat meets the friction surface, a region of extremely large temperature gradents and cyclic thermal stress.

We are talking about the face of the hat (i.e. where the holes are). Failures like the one mentioned above play no part in this discussion. The face of the hat is not subject to the same stresses as that area, seeing as how the thermal connection to the rotor is fairly weak (fairly low conductivity and a small cross section for conductive heat transfer) and it's in decent thermal contact to large heat sinks (the wheel and the hub). In addition, the face of the hat is sandwiched between the hub and the wheel, with whatever the force the lugnuts are tightened with holding it in, meaning that any stresses that the face of the rotor feels are also supported by the wheel and the hub.

Here's a homework assignment for you: Show me a 1-piece brake rotor failure due to the material in the face of the hat failing...

Asad

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Dori Dori wrote:You proved to yourself that more holes do make the rotor weaker and you already knew that not all rotors are drilled.
My point is that any loss in strength due to the extra holes is negligible, so nobody should have any qualms about redrilling rotor holes. You think otherwise. That's the whole basis of the disagreement. Haven't you been paying attention?

BTW, you still haven't shown me a rotor hat that has the lug holes cast in it -- and I never conceded that point.

I like your name just fine, I just don't like your impenetrability to logic. I also don't like it when people say stupid things like "redrilling rotors is GHEY" without providing any reason to back it up unless prodded.

Asad

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Dori Dori
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asad wrote:You're not listening. The face of the rotor HAT doesn't get to the same temperature as the friction surface! The face of the rotor HAT does not get to a temperature where the strength of the iron in the face of the HAT of the rotor is a concern!


What proof do you have of that? I've already told you of wheel bearings failing due to the heat in that area so what makes you think it doesn't get hot there? I'm not arguing that the face of the rotor sees less or the same amout of heat. I'm arguing that the hat sees plenty of heat...enough to crack a redrilled cast iron rotor in race conditions.
asad wrote:Here's a homework assignment for you: Show me a 1-piece brake rotor failure due to the material in the face of the hat failing...


Sure...I'll find one...as long as you show me where I can find a group of guys stupid enough to race (not auto-x) with redrilled cast iron rotors. I have a feeling that your assignment will be tougher than mine.

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Dori Dori
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asad wrote:My point is that any loss in strength due to the extra holes is negligible, so nobody should have any qualms about redrilling rotor holes. You think otherwise. That's the whole basis of the disagreement. Haven't you been paying attention?

BTW, you still haven't shown me a rotor hat that has the lug holes cast in it -- and I never conceded that point.

I like your name just fine, I just don't like your impenetrability to logic. I also don't like it when people say stupid things like "redrilling rotors is GHEY" without providing any reason to back it up unless prodded.

Asad


You can't prove that the strength loss is negligible and I can't prove otherwise. Nothing you've said to back up your claims is valid b/c it isn't real world. It would take full on, well thought out scientific testing under controlled conditions for either of us to prove anything. I have my opinions and you have yours. I wanted to leave it that a while ago but you keep coming back.

I never said that holes were cast in. You assumed that's what I meant. All I said is that not all rotors are drilled, and that is 100% true.

Also, what makes you think that your opinions are any better than mine? Again, they are all opinions until some real tests are done. There are just too many variable to assume 'iron rotor hat with extra holes is stronger than forged billet aluminum in race conditions'...so you are just as impervious to 'logic' as I am.

Lastly, I'm flattered that you like my name.:wiggle

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[quote=" Dori Dori What proof do you have of that? I've already told you of wheel bearings failing due to the heat in that area so what makes you think it doesn't get hot there? I'm not arguing that the face of the rotor sees less or the same amout of heat. I'm arguing that the hat sees plenty of heat...enough to crack a redrilled cast iron rotor in race conditions.[/quote]Physics is on my side. The only thing you have on your side is conjecture.

Like I said earlier, the amount of heat needed to make a wheel bearing fail is, without question, less heat than what would be required to make the the metal in the face of the rotor hat fail.

Granted, I can only make order-of-magnitude estimates of the various effects...but hey, it's better than just talking out of my ***. Quote »Sure...I'll find one...as long as you show me where I can find a group of guys stupid enough to race (not auto-x) with redrilled cast iron rotors. I have a feeling that your assignment will be tougher than mine. [/quote]Actually, I can think of one off the top of my head -- I know a guy in Canada who races in SCCA Solo-I with his turbo 240sx. He's running redrilled Z rotors and hasn't had a problem.

Remember, there are reasons BESIDES strength to use 2-pc rotors with aluminum hats. Do you honestly think that they would use a material (aluminum) that's weaker (dimension-for-dimension), has a higher coefficient of thermal expansion, and melts (and, by implication, softens) at a lower temperature if the strength requirements on the hat face were a concern? If strength were really the driving factor, race teams would be using 2 piece floating rotors with steel hats. The fact that they don't should tell you something.

Asad

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[quote=" Dori Dori You can't prove that the strength loss is negligible and I can't prove otherwise.[/quote]You're right, I can't prove it. But I have made what should be convincing plausibility arguments.

Quote »I never said that holes were cast in. You assumed that's what I meant. All I said is that not all rotors are drilled, and that is 100% true.[/quote]Ok...so if the holes aren't drilled, and they aren't cast, then how do they get there? Honestly, I'd like to know.

Quote »Also, what makes you think that your opinions are any better than mine?[/quote]There's a difference between opinions based on conjecture and opinions based on physical principles.

Asad

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Dori Dori
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1. Laser cut rotor hats aren't drilled.:)

2. Do a search on the internet for cast-in-place holes. You'll find plenty of information and debates on them. They do exist and you are not all knowing.:)

3. How much heat is needed to make a wheel bearing fail? You don't even know. you are talking out of your *** too.:)

4. Your opinions about all rotors being drilled wasn't based out of conjecture. You were talking out of your *** again, and a search on the internet will prove it.:)

5. Wow. One car uses them (the redrilled rotors). Auto-x no less. Not enough for me.:)

6. THere are racers that use steel hats. Also titanium hats.

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Dori Dori
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Here are some facts about mono-block cast iron rotors (for anyone interested...even asad cronies).

A mono-block rotor/hat has got some major thermal problems. The outer diameter of the rotor will run at up to 1300-1400degF, and it conducts this heat directly into the hub if the whole assembly is a single casting.

Cast iron is a lousy conductor of heat (as metallic solids go). Since the heat conducts directly to the hub, the wheel bearings can see temps of up to 500degF.

I can't find anyone thats done a study on the temps of the rotor hat itself, 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. If you drill once of these rotors, you are creating a stress riser...it is, afterall, a casting. With those temps, and the possible stress spot, cracking and warping are more likely to occur. Period.

There is nothing more to dispute!

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For all practical purposes, the re-drilled rotor will do fine.

I doubt that any of us will get a cross-drilled 300ZX rotor up to 1400F w/o breaking something else first, if they can even get it that hot.

Plus if anyone was that serious of a racer to get 'em that hot, and put all of the money in their car to go that fast, I'm sure they would have already done the 5-lug conversion.

Maybe there is some part of the universe where cast iron rotors crack when you go out for a joy ride, but I have never had a rotor crack on me in my life. I mean if you tried cross-drilling a240SX rotor then I would agree that you would have structural problems, but just drilling 4 extra holes in the rotor will not be anything to worry about.

I'd have to agree with asad.

Yeah I will probably do the 5-lug conversion anyway (when my budget will allow it) but thats because its a personal preference of mine and not a structural factor. Plus I think that 300ZX wheels and brakes would look killer on a 240SX. :)

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Dori Dori
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Agree with what? You think that drilled up cast iron rotors are just as strong (in real world racing) too? You also think that drilling is the only way to make a hole? Even after everything that's been posted here? Have you even read the thread? Or you just agree to agree...no real reason.

Look, I plan to track my car. That is why it matters to me. I can easily heat up my brakes to 1400degF. I don't care what most of you do. I am just stating my reasons for not liking and not buying a redrilled 5-lub rotor. All of my reasons are facts.

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hey im not here to argue.

I'm just saying that most of us here don't use our cars to race that competitavely and that most of us would be well suited with a drilled rotor.

If you think you need something more, then whip out your wallet and do the 5-lug conversion. If you are gonna race that serioiusly, then more power to ya!:ylsuper


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