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Mav1178
02-13-2002, 02:41 PM
If anyone has a set of Z32 *IRON* 30mm calipers, I would like to swap my Z32 30mm aluminum calipers with you.

Nothing is wrong with my aluminum calipers, I would just like to swap for iron calipers.

Or, if you have a pair of iron calipers available for sale off a Z32 TT, please let me know.

-alex

oldyoung240sx
02-13-2002, 02:42 PM
...................

Mav1178
02-13-2002, 02:58 PM
From the info I've gathered, aluminum calipers are no good for my use.

I do a lot of track driving in addition to daily driving. The reason why Nissan switched to the iron calipers was because the aluminum calipers were warping the rotors under heavy braking, and I am having this problem now.

In the first 2 years of owning the Z32 brakes, I never warped them. During the same time, I only ran about 2 track events, both of which were when I was starting out.

In the past year (15 months), I've ran over 10 track events. I've warped the front rotors *TWICE*, once with a set of EBC Redstuff pads and the 2nd time (most recently) with my OE Nissan pads.

I spoke to several parts managers from different dealerships (Courtesy, Mossy Nissan in Oceanside, etc). All of them mentioned that Nissan changed to iron calipers to solve the warping issue.

So, from my point of view I need to switch to the iron calipers b/c of my extensive on-track time. For someone with a daily driver (and just looking for extra braking power), the aluminum calipers work fine.

-alex

Mav1178
02-13-2002, 03:00 PM
Originally posted by fridexter:
What's the benefits and drawbacks of each? http://www.freshalloy.com/ <font size="2" face="Verdana, Arial[/img]Oops, forgot that the main issue for 240SX is that the iron calipers increase unsprung weight more than the aluminum calipers.

-alex

sr20det95
02-13-2002, 05:14 PM
I will trade you I have a 95 z32 convertable

sr20det95@hotmail.com

[ 02-13-2002, 05:15 PM: Message edited by: sr20det95 ]

cjfast_1
02-13-2002, 05:25 PM
Alex, I was wondering if you have given any thought to cryo-treated rotors before giving up on the aluminum calipers all together?

**DONOTDELETE**
02-13-2002, 09:04 PM
Is it a "heat sink" problem with the caliper material?

i.e. the aluminum calipers transferred much of the heat right to the rotors, whereas the iron calipers are a better heat sink, keeping the rotors cooler?

Pure speculation... am I on the right track?
thanks- B

[ 02-13-2002, 09:05 PM: Message edited by: Senna ]

Beef
02-13-2002, 09:14 PM
What kind of rotors are you using? Brand? Slotted? Drilled?

97 S14
02-13-2002, 09:22 PM
Originally posted by Mav1178:
From the info I've gathered, aluminum calipers are no good for my use.

I do a lot of track driving in addition to daily driving. The reason why Nissan switched to the iron calipers was because the aluminum calipers were warping the rotors under heavy braking, and I am having this problem now.

In the first 2 years of owning the Z32 brakes, I never warped them. During the same time, I only ran about 2 track events, both of which were when I was starting out.

In the past year (15 months), I've ran over 10 track events. I've warped the front rotors *TWICE*, once with a set of EBC Redstuff pads and the 2nd time (most recently) with my OE Nissan pads.

I spoke to several parts managers from different dealerships (Courtesy, Mossy Nissan in Oceanside, etc). All of them mentioned that Nissan changed to iron calipers to solve the warping issue.

So, from my point of view I need to switch to the iron calipers b/c of my extensive on-track time. For someone with a daily driver (and just looking for extra braking power), the aluminum calipers work fine.

-alex<font size="2" face="Verdana, Arial[/img]I posted the same statement last year about the aluminum calipers warping rotors easier than iron calipers and a bunch of people basically called me an idiot. Hope they're reading now.

cjfast_1
02-13-2002, 09:29 PM
Originally posted by Senna:
Is it a "heat sink" problem with the caliper material?

i.e. the aluminum calipers transferred much of the heat right to the rotors, whereas the iron calipers are a better heat sink, keeping the rotors cooler?

Pure speculation... am I on the right track?
thanks- B<font size="2" face="Verdana, Arial[/img]Yah, your right. That's why Nissan switched to the cast iron calipers in the later yr 300zx's

cjfast_1
02-13-2002, 09:32 PM
Originally posted by 97 S14:
</font><blockquote><font size="1" face="Verdana, Arial[/img]quote:</font><hr /><font size="2" face="Verdana, Arial[/img]Originally posted by Mav1178:
From the info I've gathered, aluminum calipers are no good for my use.

I do a lot of track driving in addition to daily driving. The reason why Nissan switched to the iron calipers was because the aluminum calipers were warping the rotors under heavy braking, and I am having this problem now.

In the first 2 years of owning the Z32 brakes, I never warped them. During the same time, I only ran about 2 track events, both of which were when I was starting out.

In the past year (15 months), I've ran over 10 track events. I've warped the front rotors *TWICE*, once with a set of EBC Redstuff pads and the 2nd time (most recently) with my OE Nissan pads.

I spoke to several parts managers from different dealerships (Courtesy, Mossy Nissan in Oceanside, etc). All of them mentioned that Nissan changed to iron calipers to solve the warping issue.

So, from my point of view I need to switch to the iron calipers b/c of my extensive on-track time. For someone with a daily driver (and just looking for extra braking power), the aluminum calipers work fine.

-alex<font size="2" face="Verdana, Arial[/img]I posted the same statement last year about the aluminum calipers warping rotors easier than iron calipers and a bunch of people basically called me an idiot. Hope they're reading now.</font><hr /></blockquote><font size="2" face="Verdana, Arial[/img]Sorry people were 'hatin' on you. I found this 'problem' out after doing research on the 300zx upgrade. I would have backed you up...

**DONOTDELETE**
02-13-2002, 10:28 PM
just outta curiousity what year did they start making iron calipers for the Z?

Mav1178
02-14-2002, 01:16 AM
Currently I am running a set of Powerslot slotted rotors. They are not cryo-treated.

I might just get a new set of rotors and pads, and see if it works out.

I'll keep doing more research on the subject.

-alex

ADAM HUTCHINSON
02-14-2002, 05:48 AM
hi alex,

i would go to a x-drilled set, and duct the calipers...slotted would not have near the heat dissipation of the x-drilled...

i have aluminum 300zx as well http://www.freshalloy.com/

also i thought aluminum as a material is a better conductor of heat? no...they make alot of heat sinks from aluminum? anyone have any charts on heat dissipation characteristics of some common metals?

arkman0
02-14-2002, 05:50 AM
you probably already do this, but make sure you torque the lugs with a torque wrench... exact same thing was happenin to my buddy. When he torqued them, his rotors never warped again.
can you get powerslot rotors turned?
Noah

ADAM HUTCHINSON
02-14-2002, 05:58 AM
here is a good chart with properties of thermal conductivity..it seems aluminum is very good..

http://metals.about.com/gi/dynamic/offsite.htm?site=http%3A%2F%2Fwww.apo.nmsu.edu%2FT elescopes%2FSDSS%2Feng.papers%2F19950926%255FConve rsionFactors%2F19950926%255FMProperties.html

it might be......that for street use aluminum is bad..because street drivers have a bad tendancy to keep thier foot on the brake after hard braking...thus the pad is in contact with the rotor......so if aluminum can transfer the heat in a faster period of time over cast iron..then more heat would be forced into the rotor..vs iron would take longer....i think that the delta rise in temp is what might be killing the rotors?(delta rise in temp is the correct term...asad?) help us out here...

**DONOTDELETE**
02-14-2002, 07:48 AM
An aside question: I assume in doing the swap you did away with the dust shields? I know these hold a fair amount of heat in on the rotor. Considered a basic duct?

I'm sure both answers will be yes, but for posterity, I'm curious...

duncan351
02-14-2002, 08:06 AM
I'm glad I saw this post. That explains why I have this problem. Though I don't do a lot of track events. I drive my car very hard and brake even harder. I noticed the problem but never investigated it. Thanks for the heads up!

'97 S14 SE Turbo
02-14-2002, 08:38 AM
For some reasons, I don't have this problem. One thing that may have helped me is that my dust shields were deeply cut away such that lots more airflow could get into the rotors.

Also, don't ride the brakes. I jab them to keep the "on" time down on the brakes.

and my car is heavyyyyyyy, and still no problem. So, it's a cooling issue, check the dust shield, and modify brake usage habit...

02-14-2002, 08:42 AM
I think the track you run at has a big effect...I've run at ThunderHill, which has plenty of distance between heavy braking zones so I've never had any issue with brake fade...but on a really tight course, it might be different.

Asad

02-14-2002, 08:45 AM
Originally posted by Senna:
Is it a "heat sink" problem with the caliper material?

i.e. the aluminum calipers transferred much of the heat right to the rotors, whereas the iron calipers are a better heat sink, keeping the rotors cooler?
<font size="2" face="Verdana, Arial[/img]This explanation doesn't make sense to me for one reason: The rotors are HOTTER than the calipers...so heat would be transferred from the rotors to the calipers. And the aluminum calipers, having a higher thermal conductivity, should be able to absorb heat more quickly from the rotors. The other side of the coin is that for a given amount of heat absorbed by the calipers, the aluminum ones will heat up more than the iron ones...so perhaps that has some effect. I'm really not sure what the mechanism for warping the rotors is though...

Asad

import silvia
02-14-2002, 09:39 AM
The Al calipers will with out a doubt have a greater cooling capacity. Al is a much better conductor of heat than Fe. I would theorize that the warpage is not a result of cooling, heat retention, or over heating durring use but rather, when the car is parked the portion of the rotor under the caliper will cool faster than the rest of the caliper causing the warping. With Fe rotors and calipers everything will cool in a uniform manner preventing the damaging uneven cooling.

pzofsak
02-14-2002, 09:56 AM
To answere a few questions and clear up some things, Nissan started producing the iron calipers in 93'. Aluminum is a great conductor of heat but because it is not as dense as iron it conducts the heat very unevenly. This would cause uneven expansion over the caliper as a whole as temps rise and fall rapidly. Heavy braking and then, lets say hitting a puddle of water, could cause the calipers to contract on the bottom but not on top causing uneven pressure on the rotor, warping it.

cjfast_1
02-14-2002, 09:58 AM
Originally posted by import silvia:
The Al calipers will with out a doubt have a greater cooling capacity. Al is a much better conductor of heat than Fe. I would theorize that the warpage is not a result of cooling, heat retention, or over heating durring use but rather, when the car is parked the portion of the rotor under the caliper will cool faster than the rest of the caliper causing the warping. With Fe rotors and calipers everything will cool in a uniform manner preventing the damaging uneven cooling.<font size="2" face="Verdana, Arial[/img]Good theory.

I thought that this wouldn't be a problem with 240's due to the substantial weight difference between the 240's and 300zx's. Well, I guess I was wrong on that one.... But I still wonder if cyro-treated rotors would make a difference here...

import silvia
02-14-2002, 10:29 AM
Originally posted by pzofsak:
To answere a few questions and clear up some things, Nissan started producing the iron calipers in 93'. Aluminum is a great conductor of heat but because it is not as dense as iron it conducts the heat very unevenly. This would cause uneven expansion over the caliper as a whole as temps rise and fall rapidly. Heavy braking and then, lets say hitting a puddle of water, could cause the calipers to contract on the bottom but not on top causing uneven pressure on the rotor, warping it.<font size="2" face="Verdana, Arial[/img]We are dealing with elemental chemical constants here density is separate and different from thermal conductivity. The fact of the mater is Al will be more uniform at any one time in its thermal signature presented to the Fe rotor because it is more thermally conductive. If, as in your scenario, a hot Al caliper is splashed with cool water it will cool off more rapidly and to a greater degree than the same Fe caliper. However the Al caliper will also reach a uniform temp faster than the Fe one because of its higher thermal conductivity value. Now a Fe caliper will be more uniform in its temperature over time. Once it reaches its operating temperature it will be less affected by temporary changes in its environment because of the larger amount of energy change required to change its temp. The higher density of the Fe caliper means it is heavier than itís Al counterpart, which exasperates this difference, as energy capacity is a function of mass. The bottom line is Al has a greater overall cooling capacity but Fe will stay at a more stable temperature.

Mav1178
02-14-2002, 11:19 AM
I had my rotors turned at a shop that has the machine capability to turn slotted/crossdrilled rotors.

I *always* torque down my wheels by hand, with a torque wrench to 80 ft-lb of torque. Even when a shop works on my car, I ask to torque down the wheels myself. I don't trust mechanics to torque down the wheels... they never do it right.

As for the tracks, I've only ran at Buttonwillow, Streets of Willow, WSIR (big track), and Laguna Seca over the past year. It puzzles me, because Buttonwillow is a relatively fast track, and so are WSIR and Laguna. The only track on which I have to work the brakes hard is Streets of Willow, but I have only driven there twice in the past year.

T.Y. made a good point on the OE S13 dust shield.

I might just go with a custom brake duct to solve this problem (if it can be considered a problem for the time being).

As for driving/braking habits, I never ride the brakes, nor do I overwork the brakes on streets. When I am at track events, I always allow myself one (or two) cooldown laps, where I lay off the brakes and gas pedal and cool the car down. I also never park the car immediately in the pits, but rather drive around a bit before parking.

It just puzzles me.

The only weird thing is that prior to rebuilding my calipers early last year, I had Stillen sport rotors (crossdrilled Brembo rotors). They came from the junkyard (along with my then-super-cheap calipers). I drove on them for 2+ years without any sort of warping problems, but this was before I started out with track events.

Puzzling. Perhaps it is a cooling problem, perhaps it is something else. All I know is that something is causing my rotors to warp prematurely, and it's taking a toll on my wallet. 2 sets of rotors and 3 sets of pads in 18 months isn't cool...

-alex

cjfast_1
02-14-2002, 11:41 AM
Hey Alex & others, take a look at this. http://www.ws6.com/cryo.htm

cjfast_1
02-14-2002, 02:11 PM
Alex,

I just found this place down your way (So. Cal) that is a little cheaper then the 80.00 bucks your talkin about. http://www.cryoscience.com/index.htm And hey, look at this way, the extra 50 - 60 dollars you spend is better then the hassle & time you'll spend changing out rotors.... I'm sure it'll equal itself out in the long run.

[ 02-14-2002, 02:23 PM: Message edited by: cjfast_1 ]

White_240sx
02-14-2002, 09:50 PM
Hey Alex, what about the pads? It's the track brakes that warp, not the street set right? Maybe a less aggressive track pad will be a little kinder on the rotors... http://www.freshalloy.com/

Mav1178
02-15-2002, 12:06 AM
Originally posted by cjfast_1:
Hey Alex & others, take a look at this. http://www.ws6.com/cryo.htm<font size="2" face="Verdana, Arial[/img]Great info....

But, the rotors he talks about are cracking and are expensive rotors mated to big brake calipers. The Z32 rotors are considered "regular" OE rotors, not like the big Brembo brake kits.

And I haven't been able to find a place that would cryo-treat rotors for cheaper than $80 for the front two. At that price, it's almost as much as a set of OE Brembo blanks!

-alex

Mav1178
02-15-2002, 12:37 AM
Originally posted by White240sx:
Hey Alex, what about the pads? It's the track brakes that warp, not the street set right? Maybe a less aggressive track pad will be a little kinder on the rotors... http://www.freshalloy.com/ <font size="2" face="Verdana, Arial[/img]Actually, I only ran the EBC Red's *ONCE*, at one track event last January.

The rest of the time, it was all OE Nissan pads.

-alex

pzofsak
02-15-2002, 08:42 AM
Importsilvia, I think you are missing my point; since the Al is less dense than the Fe it has less structual ridigity causing it to warp under extreme temp changes. If you take a flat piece of Al and Fe and heat them to the same temp, then dunk them into water, you will see that the Al has warped and the Fe has remained unchanged.

02-15-2002, 08:47 AM
I think you're missing the point -- it's not the CALIPERS that warp, it's the ROTORS, which are cast iron in both cases.

Asad


Originally posted by pzofsak:
Importsilvia, I think you are missing my point; since the Al is less dense than the Fe it has less structual ridigity causing it to warp under extreme temp changes. If you take a flat piece of Al and Fe and heat them to the same temp, then dunk them into water, you will see that the Al has warped and the Fe has remained unchanged.<font size="2" face="Verdana, Arial[/img]

YellowS14
02-15-2002, 09:03 AM
alex, i dont remember the site, but when i was searching for site that show about rebuilding the z calipers i crossed a site that showed a guy installing an nissan optional z part that was an underneath brake duct that attached to the suspention(im sure itd convert easily to an s13)

also, from what i know about the brakes, the aluminum are better for track because they dissapate the heat quickly, theyre bad for daily driver because they heat quickly, and noone ever let there brakes cool down before parking the z so they warped, the iron take longer to absorb heat so it wont effect..lets say...someone tearing ass to the grocery store as much as the aluminum would

they replaced them with iron because noone used them the correct way, its kindof like turbos, noone knew how to warm up or cool down there car, so people thought they were bad, and companys stopped making them(us at least), or replaced them with somthing more "user friendly"

but as long as you park your car with a cool down lap on it, you should be fine...

also watch those hot laps to the store jk hehehe

TroyC http://www.freshalloy.com/

halz
02-15-2002, 09:08 AM
Considering that aluminum has a higher thermal conductivity, using forced air (ducted) to cool the rotors could be an option

**DONOTDELETE**
02-15-2002, 09:09 AM
Originally posted by Mav1178:
I *always* torque down my wheels by hand, with a torque wrench to 80 ft-lb of torque. Even when a shop works on my car, I ask to torque down the wheels myself. I don't trust mechanics to torque down the wheels... they never do it right.

-alex<font size="2" face="Verdana, Arial[/img]Something that I learned at my last HPDE event was to take a torque wrench with you an re-spec before each session on the track. It's incredible how much they loosen between runs. (unlikely enough to warp rotors, but who knows...)

I hope the heat shields do the trick. If not, perhaps you can be the first to put some dryer ducting to use on a 240;)

import silvia
02-15-2002, 09:55 AM
Originally posted by pzofsak:
Importsilvia, I think you are missing my point; since the Al is less dense than the Fe it has less structual ridigity causing it to warp under extreme temp changes. If you take a flat piece of Al and Fe and heat them to the same temp, then dunk them into water, you will see that the Al has warped and the Fe has remained unchanged.<font size="2" face="Verdana, Arial[/img]No, I feel you are over simplifying the subject and providing anecdotal findings as a proof for you theory. The density has nothing to do with the strength of a metal or we would all want those new Lead (Pb) brakes. Titanium (Ti) is a very strong metal but just over half the density of Fe, 4.5 g/ml to 7.86 g/ml. Ti is also very stable when exposed to high temperature, the SR-71 (+3 mach aircraft) has a skin made of Ti that repeatedly reached temperatures between 600 and 900 degrees F during flight ops. Your less structural rigidity statement leads me to believe you view Al as a styro-foam like metal with free space between the atoms. This is certainly not the case, while Al has a slightly larger atomic radius than Fe, 1.82 A vs. 1.72 A, they are packed together equally tightly in their respective solid forms. Also, they both form cubic crystals so even their grain pattern would be similar. So Iím not missing your point, Iím just not seeing you proof to your theories. By all means go out do some research and provide either facts or repeatable findings and I willÖÖ well Iíll still be disagreeable but it will be on a professional scientific level. http://www.freshalloy.com/ Here, check out Periodic Table (http://140.198.18.108/periodic/periodic.html) and throw down some scientific theories.

edit- Feel free to call me James

[ 02-15-2002, 09:58 AM: Message edited by: import silvia ]