<TABLE cellSpacing=1 cellPadding=6 width="100%" border=0><TBODY><TR><TD colSpan=2><TABLE width="100%" border=0><TBODY><TR><TD style="PADDING-TOP: 4px" vAlign=top colSpan=2>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]question about X brake rotors<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 10 2001 at 2:10 PM[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "m";n54_em = n54_em + "a";n54_em = n54_em + "c";n54_em = n54_em + "@";n54_em = n54_em + "s";n54_em = n54_em + "e";n54_em = n54_em + "a";n54_em = n54_em + "t";n54_em = n54_em + "t";n54_em = n54_em + "l";n54_em = n54_em + "e";n54_em = n54_em + "x";n54_em = n54_em + "1";n54_em = n54_em + "9";n54_em = n54_em + ".";n54_em = n54_em + "o";n54_em = n54_em + "r";n54_em = n54_em + "g"; document.write("Mac"); // --> </SCRIPT>Mac <NOSCRIPT> Mac </NOSCRIPT> [/FONT]</TD></TR><TR><TD vAlign=bottom colSpan=3><HR></TD></TR><TR><TD colSpan=3>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->It's not often that I plug or talk about vendors around here, I try to stay neutral in that department unless I deem something "noteworthy" or `gasp' "must be made public"
This one is from the 1st category
IAP is having a sale right now, in the classical terminology, "...to make room for new inventory". Normally I would not bother to mention vendor doings here except that I happened to notice that they have, 'direct from Italy', new X brake rotors that are cross-drilled and slotted at what amounts to $35 each (plus then shipping of course)...
That's only ten bucks more each than the bone stock new rotors that Holly put on her red '74 not long ago from one of the more commonly recognized vendors...
SO my question is, are these rotors something that the "average" (if there is such a thing) X1/9 owner would benefit to use in a non-racing application (ie: street) or would one be no further on than stock rotors except the agressive aesthetic plus?
Just curious. I have never used such rotors on an X1/9 myself, but was under the impression that, while slots are good, cross-drilling tends to make the unit much more succeptible to cracking?
Opinions please
-Mac.
PS: For reference, the IAP pages - I am drooling over the Evo car cover now that my X is garageless!
http://www.international-auto.com/catalog/cgi-bin/newproducts.pl
http://www.international-auto.com/catalog/cgi-bin/specials1.pl
<!-- google_ad_section_end -->
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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]Author[/FONT]</TD><TD>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]Reply[/FONT]</TD></TR><TR><TD vAlign=top noWrap width="17.9%">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "m";n54_em = n54_em + "f";n54_em = n54_em + "r";n54_em = n54_em + "e";n54_em = n54_em + "e";n54_em = n54_em + "m";n54_em = n54_em + "a";n54_em = n54_em + "n";n54_em = n54_em + "i";n54_em = n54_em + "s";n54_em = n54_em + "@";n54_em = n54_em + "h";n54_em = n54_em + "o";n54_em = n54_em + "t";n54_em = n54_em + "m";n54_em = n54_em + "a";n54_em = n54_em + "i";n54_em = n54_em + "l";n54_em = n54_em + ".";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "m"; document.write("Mark Freeman"); // --> </SCRIPT>Mark Freeman <NOSCRIPT> Mark Freeman </NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->interesting...<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 10 2001, 3:56 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I doubt they would be of much benefit outside of a racing environment though. I haven't found the X brakes to be lacking using my basic rule of thumb:
"Can I lock up the front wheels at will without breaking my seat?" In the X, I always seem to run out of grip first.
That said, I wouldn't mind trying a pair of these anyway, just for interest.
Susceptability to cracking can be an issue with drilled rotors but a lot depends on how they were made.
Mark Freeman
Newcastle WA
79 1500 dual 36DCNF Autocrosser
81 1500 FI street - under restoration<!-- google_ad_section_end -->
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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "s";n54_em = n54_em + "t";n54_em = n54_em + "i";n54_em = n54_em + "l";n54_em = n54_em + "l";n54_em = n54_em + "e";n54_em = n54_em + "r";n54_em = n54_em + "@";n54_em = n54_em + "v";n54_em = n54_em + "r";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "m";n54_em = n54_em + ".";n54_em = n54_em + "d";n54_em = n54_em + "e"; document.write("Matthias Stiller"); // --> </SCRIPT>Matthias Stiller <NOSCRIPT> Matthias Stiller </NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Don't know ....<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 10 2001, 11:04 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->where Holly bought their set but the average price for a set (2) of standard brake discs here in Europe is about DM 50 which equals about US-$ 25.
So I wouldn't conside this offer as ultra cheap.
Regards
Matthias<!-- google_ad_section_end -->
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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "g";n54_em = n54_em + "b";n54_em = n54_em + "7";n54_em = n54_em + "2";n54_em = n54_em + "3";n54_em = n54_em + "8";n54_em = n54_em + "@";n54_em = n54_em + "h";n54_em = n54_em + "o";n54_em = n54_em + "m";n54_em = n54_em + "e";n54_em = n54_em + ".";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "m"; document.write("Greg Barron"); // --> </SCRIPT>Greg Barron <NOSCRIPT> Greg Barron </NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->drilled rotors<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 11 2001, 2:03 AM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Mac,
I was recently in the Dallas, TX area visiting my dad. While there, I stopped in and met the folks at Vick's Auto. They were great and very informative. One of the things I asked them about were the slotted brake rotors that they sell. It was overwhelmingly unanimous that there only benefit was aesthetics. They told me that they don't even run them on their race cars. They use the stock (cheap) rotors that they sell for I believe around $15.00 each. They told me that there was no gained benefit, so why waste the money?
Hope this helps in your decision.
Greg
'76 X and '80 Parts car<!-- google_ad_section_end -->
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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "n";n54_em = n54_em + "a";n54_em = n54_em + "t";n54_em = n54_em + "o";n54_em = n54_em + "l";n54_em = n54_em + "i";n54_em = n54_em + "a";n54_em = n54_em + "l";n54_em = n54_em + "@";n54_em = n54_em + "p";n54_em = n54_em + "a";n54_em = n54_em + "c";n54_em = n54_em + "b";n54_em = n54_em + "e";n54_em = n54_em + "l";n54_em = n54_em + "l";n54_em = n54_em + ".";n54_em = n54_em + "n";n54_em = n54_em + "e";n54_em = n54_em + "t"; document.write("Tony Natoli"); // --> </SCRIPT>Tony Natoli <NOSCRIPT> Tony Natoli </NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Let me cast vote # 4...<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 11 2001, 5:34 AM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I have never used the slotted rotors so I must base my X-perience on what I have used.
1. As one other writer said... I run outta tire before I run outta brake... and I play pretty rough on the street, in the hills, and in LA traffic.
2. The ENTIRE system is the same as used on the much heavier 124... Hmmmmmmm!
3. As with one other writer... The MOST I have paid for a rotor was 16.50... So I can buy the same set of 4 for the price of 2 of the slotted.
4. If it was aesthetics I was going after... I find it still difficult to do if I gotta bend over and peer through the mag slots to see them... I'd spend the money elsewhere.
5. As I said, with no personal background... I still think the drilled rotors would be a benefit in RACING... and as for cracking... I would assume these rotors would be replaced quite frequently anyway.
Good to see yur 'up and around'... take care,
Best Regards,
Tony Natoli
Two '79s, WHITE FANG and BLACK TOOTH
Santa Clarita, CA<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]Warren[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I Have em, I use em on the street and track, they make a difference. use em.<NT><!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 11 2001, 9:41 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->.<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]scot[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->drilled discs, good<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 11 2001, 10:29 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I drilled mine for two reasons. 1/2 lb rotating, unsprung weight is a significant reduction. allso, in a pouring rain drilled discs start to work a little sooner than not drilled. No cracking problems, I peened each hole as recomended by Carol Smith in one of his books. I also am fairly easy on brakes.<!-- google_ad_section_end -->
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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "s";n54_em = n54_em + "t";n54_em = n54_em + "e";n54_em = n54_em + "v";n54_em = n54_em + "e";n54_em = n54_em + "h";n54_em = n54_em + "h";n54_em = n54_em + "@";n54_em = n54_em + "h";n54_em = n54_em + "i";n54_em = n54_em + "w";n54_em = n54_em + "a";n54_em = n54_em + "a";n54_em = n54_em + "y";n54_em = n54_em + ".";n54_em = n54_em + "n";n54_em = n54_em + "e";n54_em = n54_em + "t"; document.write("Steve Hoelscher"); // --> </SCRIPT>Steve Hoelscher <NOSCRIPT> Steve Hoelscher </NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 30px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Drilled/Slotted and Racing<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 12 2001, 8:28 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 30px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I have a great deal of experience with drilled and rotors on X1/9s. I have had Brembo drilled rotors on my '74 for some time. These have seen lots of track use. I also had a set of them on another car as well. These saw lots of fast street duty. I use the stock rotors on my race car.
What makes brakes work is surface area and mass. The surface area is where the friction is produced. More surface area on the rotor equals more stopping power. More mass enables the rotor to absorb more heat and because the function of the brakes is to turn motion energy to heat engery, the ability of the rotor to absorb heat is of the utmost importance. Drilling or slotting the rotors reduces both surface area and mass. Therefore, they reduce brake performance.
The reason for drilling rotors is either: 1) to allow for airflow on a vented rotor (X1/9 rotors are not vented) or 2) reduce mass. On some racing applications, the rotors are oversized so they can be drilled for lightness and the resulting mass and surface area is adequate for the weight and performance of the vehicle. The reason for this is a larger diameter rotor has more mechanical advantage over the tire. Also the surface area and mass is significantly increased from a small increase in diameter. Therefore, a large diameter drilled rotor produces a more effective brake package for a given weight.
A properly setup X1/9 brake system has truely amazing braking power. I use all stock components on my racecar; calipers, lines, master cylinder and rotors. The only thing that has changed are the pads, fluid and the removal of the backing plates. Last fall, John Montgomery, X1/9 owner and president of FLU (Fiat Lancia Unlimited), rode in my racecar on the road course at Talladega. The first corner we hit at full speed he nearly paniced. Afterward, his very first comment about the car was the brakes. I did over 30 laps that day hammering the brakes at every corner on every lap. They never once let me down and at the end of the day, the rotors look fine. The pads were kind of spent, but they had two seasons of autocrossing on them before getting there.
As for slotting, some brake pad compounds are designed to be used with slotted rotors. Tarox is one of these. The purpose of the slots is to remove the gasses produced by heat and friction.
As for shedding water. Water is unlikely to cling to the brake rotor. Remember it is spinning and therefore any water on the rotor would be slung off. Further more, if the brakes are being used heavily, then the water would vaporize as soon as it hit the hot rotor.
Steve
<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]scot[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 45px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->wet brakes and drilled rotors<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 12 2001, 10:48 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 45px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Steve,I'm sure you're are correct about the x brakes under racing conditions.But when cold and soaked, as when driving almost any winter day here in Seattle, the drilled rotors do give full power sooner than undrilled. Maybe the pads or rotor absorb some water that goes to vapor when the brakes are applied? both are porous to some extent.<!-- google_ad_section_end -->
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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "r";n54_em = n54_em + "h";n54_em = n54_em + "i";n54_em = n54_em + "l";n54_em = n54_em + "l";n54_em = n54_em + "6";n54_em = n54_em + "@";n54_em = n54_em + "n";n54_em = n54_em + "c";n54_em = n54_em + ".";n54_em = n54_em + "r";n54_em = n54_em + "r";n54_em = n54_em + ".";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "m"; document.write("Rob"); // --> </SCRIPT>Rob <NOSCRIPT> Rob </NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 30px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Some late-night engineering comments<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 13 2001, 11:23 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 30px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Hey Steve -
It's hard to counter your argument about mass and heat dissipation (your responses are always so logical, well thought out, and simple
). But I thought I'd take my stab at a couple of "common sense" items on this subject, too. You got me to thinking about my old physics classes. Doesn't drilling a rotor increase the coefficient of friction? (Consider running your hand across a smooth countertop versus a vegetable grater.) Then, wouldn't the slots also enhance the heat transfer/dissipation (i.e., airflow) from the rotor, therefore making them more efficient?
Assuming the pads are properly matched for the given rotor type, the winner would boil down to the rotor with the highest energy/heat transfer rate to the surroundings. Peening or chamfering the drill holes to prevent cracking would decrease the friction somewhat (but might enhance the surface area for cooling).
In my opinion, drilled/slotted rotors should be an appreciable improvement for normal street driving (by increasing the friction - the "bite"). They should also be best for racing (because of the increased energy transfer to and from the rotor), as well as enabling higher-temperature operation. Rob Hill
Raleigh, NC
80 Rosso X1/9
Potenza = Velocita
<!-- google_ad_section_end -->
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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "s";n54_em = n54_em + "t";n54_em = n54_em + "e";n54_em = n54_em + "v";n54_em = n54_em + "e";n54_em = n54_em + "h";n54_em = n54_em + "h";n54_em = n54_em + "@";n54_em = n54_em + "h";n54_em = n54_em + "i";n54_em = n54_em + "w";n54_em = n54_em + "a";n54_em = n54_em + "a";n54_em = n54_em + "y";n54_em = n54_em + ".";n54_em = n54_em + "n";n54_em = n54_em + "e";n54_em = n54_em + "t"; document.write("Steve Hoelscher"); // --> </SCRIPT>Steve Hoelscher <NOSCRIPT> Steve Hoelscher </NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 45px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Some early-morning engineering assumptions<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 14 2001, 9:00 AM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 45px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->"doesn't drilling the rotor increase the co-efficient of friction?"
In your example of the vegetable grater it does. The vegetable grater depends on the edges of the holes to bite into the soft vegetable for resistance. The result is a very high wear rate! Which is of course what the vegetable grater is desiged to do. The other thing it does in increase the clamping pressure. By reducing surface area the force applied by the caliper piston is distributed over a smaller surface area of the drilled rotor and pad. The higher pressure exerted over a smaller area increases the wear rate and heat generated. The increase in heat generated will also increase the wear on the surface of the pad and rotor.
For a moment, lets return to the vegetable grater. Consider what the vegetable grater does to the vegetable (or your hand!) and then think of that happening to your brake pad!!! Your brake pads will wear out quickly.
Now lets make another comparison. A racing slick to a snow tire. The reason the racing slick is slick is two fold; one, maximize the contact patch of the tire. And two, minimize wear and heat buildup. The reason the snow tire has knobs and groves is to cut into to soft snow (a high friction co-efficient). In doing so the snow has a very high wear rate! But wouldn't running the snow tire on dry pavement out perform the slick? It has a higher psi for a given load. It allows airflow around the tread blocks to cool them. The agressive tread pattern will have a high friction co-efficient. (The same argument for the drilled rotor right?) In practice, the snow tire cannot absorb the heat generated by the high friction co-efficient and the resulting wear rate will quickly ruin the tire.
A key point to remember in this argument is the design of the rotor. Drilled rotors are also vented. This means the rotor has two friction surfaces (a front and back) with an air gap in between. The air gap is bridged by vanes which structually connect the two friction surfaces and act as an air pump. As the rotor spins, air is drawn in through the holes and pumped out along the edge by the vanes. This is where the airflow comes from. The back side of the friction surface and the vanes provide for a great deal of surface area to be contacted by the flow of air. Simply drilling through a solid rotor (as is the case in the X rotors) does not provide for airflow as is the case in a vented rotor. Drilling through the solid rotor only reduces the surface area because removes more area on the surface of the rotor than it gains on the walls of the holes. Finally, there is no mechanism to remove the heat that builds up in the holes because there is no airflow through the holes.
Slotting the surface of the rotor does not provide for airflow over the rotor as the slots are too small to have any influence. The slotting allows an escape path for the gasses that build up between the pad and rotor and actually cause the pad to "hydroplane" the same way a tire does on water. Again, slotting should only be used with pads that require it.
Brake pads and rotors are designed for a balance of long life and performance. A manufacturer of street cars wants his brakes to provide adequate perfomance with long life. Drilling or slotting the rotors will reduce the life of both components. Notice that few production cars use drilled or slotted rotors and those that due have very large diameter rotors to make up for the loss in surface area and mass. In racing applications, the battle is always to combat heat. Overheating the brakes will cause them to wear quickly and possibly wear out before the end of the race. Airflow is critical in this application. I am sure you have seen the massive brake ducts on most racing cars. Brake rotors are sized as large as possbile with drilling and venting to provide for as much airflow as possible.
Now lets go back to the rotors on an X1/9. The solid rotor (like our slick in a previous example) provides for as much surface area to contact the pad as possible and also for as much mass as possible to absorb the heat produced. The low friction co-efficient is offset by the increase in contact area. Drilling the solid rotor will increase the friction co-efficient, but the pad life will suffer. In addition, it may provide for more braking power on a single stop, but then requires more time to cool before maximum performance will return.
In practice, on the street, drilled rotors will wear the pads and rotors faster than solid rotors. They may also provide a slight improvement in absolute stopping power for a single stop. In competition use, drilled rotors will wear the pads and rotors much faster than solid rotors. They will also reduce braking performance and life as the rotors and pads will be forced to operatate at a higher temperature and have less surface area to absorb energy and dissapate heat.
The ideal performance brake package is a large diameter rotor, to provide for mechanical advantage over the tire and a lot of mass to absorb heat, that is vented and drilled to provide for airflow to dissapate heat. The large diameter provides for enough additional mass that the mass lost through drilling does not degrade the heat absorbtion to the point of performance loss. The pad is compounded hard enough to survive the wear resulting from the friction co-efficent for the duration of the race.
The ideal street brake package is much the same, with the exception that the rotors not be drilled so as to provide for long service life and low cost to manufacture.
Steve
<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]Warren[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 60px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Hey guy's listen to Steve, How meany championsips has evry one else won? <NT><!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 14 2001, 10:44 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 60px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->it makes sence.<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]scot[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 60px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->No argument, you make a good case. But aren't you saying<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 15 2001, 10:41 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 60px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->the x's brakes have more heat storage than needed for street use?(They work well with no major modification under hard racing use) In street use, doesn't it seem worth trading some heat storage( mass)for better acceleration,ride, and roadholding? Street and race conditions are different.<!-- google_ad_section_end -->
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[/FONT]</TD></TR></TBODY></TABLE></TD></TR><TR><TD vAlign=top noWrap width="17.9%">[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "s";n54_em = n54_em + "t";n54_em = n54_em + "e";n54_em = n54_em + "v";n54_em = n54_em + "e";n54_em = n54_em + "h";n54_em = n54_em + "h";n54_em = n54_em + "@";n54_em = n54_em + "h";n54_em = n54_em + "i";n54_em = n54_em + "w";n54_em = n54_em + "a";n54_em = n54_em + "a";n54_em = n54_em + "y";n54_em = n54_em + ".";n54_em = n54_em + "n";n54_em = n54_em + "e";n54_em = n54_em + "t"; document.write("Steve Hoelscher"); // --> </SCRIPT>Steve Hoelscher <NOSCRIPT> Steve Hoelscher </NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 75px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->X Brakes<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 17 2001, 5:23 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 75px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->You make a good point, but there are two things to remember: 1st, the X is an enthusiast car and Fiat knows its customers drive their cars hard. So having some extra brake capacity is a good thing. 2nd, It was quicker, easier and cheaper to use the existing brake packages from its parts bin (124/128/etc...) than to design and manufacture an entirely new system for a realatively low production car.
Steve
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[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 10 2001 at 2:10 PM[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "m";n54_em = n54_em + "a";n54_em = n54_em + "c";n54_em = n54_em + "@";n54_em = n54_em + "s";n54_em = n54_em + "e";n54_em = n54_em + "a";n54_em = n54_em + "t";n54_em = n54_em + "t";n54_em = n54_em + "l";n54_em = n54_em + "e";n54_em = n54_em + "x";n54_em = n54_em + "1";n54_em = n54_em + "9";n54_em = n54_em + ".";n54_em = n54_em + "o";n54_em = n54_em + "r";n54_em = n54_em + "g"; document.write("Mac"); // --> </SCRIPT>Mac <NOSCRIPT> Mac </NOSCRIPT> [/FONT]</TD></TR><TR><TD vAlign=bottom colSpan=3><HR></TD></TR><TR><TD colSpan=3>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->It's not often that I plug or talk about vendors around here, I try to stay neutral in that department unless I deem something "noteworthy" or `gasp' "must be made public"
This one is from the 1st category
IAP is having a sale right now, in the classical terminology, "...to make room for new inventory". Normally I would not bother to mention vendor doings here except that I happened to notice that they have, 'direct from Italy', new X brake rotors that are cross-drilled and slotted at what amounts to $35 each (plus then shipping of course)...
That's only ten bucks more each than the bone stock new rotors that Holly put on her red '74 not long ago from one of the more commonly recognized vendors...
SO my question is, are these rotors something that the "average" (if there is such a thing) X1/9 owner would benefit to use in a non-racing application (ie: street) or would one be no further on than stock rotors except the agressive aesthetic plus?
Just curious. I have never used such rotors on an X1/9 myself, but was under the impression that, while slots are good, cross-drilling tends to make the unit much more succeptible to cracking?
Opinions please
PS: For reference, the IAP pages - I am drooling over the Evo car cover now that my X is garageless!
http://www.international-auto.com/catalog/cgi-bin/newproducts.pl
http://www.international-auto.com/catalog/cgi-bin/specials1.pl
<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top noWrap align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<SCRIPT language=Javascript> <!-- var n54_em; n54_em = ""; n54_em = n54_em + "m";n54_em = n54_em + "f";n54_em = n54_em + "r";n54_em = n54_em + "e";n54_em = n54_em + "e";n54_em = n54_em + "m";n54_em = n54_em + "a";n54_em = n54_em + "n";n54_em = n54_em + "i";n54_em = n54_em + "s";n54_em = n54_em + "@";n54_em = n54_em + "h";n54_em = n54_em + "o";n54_em = n54_em + "t";n54_em = n54_em + "m";n54_em = n54_em + "a";n54_em = n54_em + "i";n54_em = n54_em + "l";n54_em = n54_em + ".";n54_em = n54_em + "c";n54_em = n54_em + "o";n54_em = n54_em + "m"; document.write("Mark Freeman"); // --> </SCRIPT>Mark Freeman <NOSCRIPT> Mark Freeman </NOSCRIPT>[/FONT]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->interesting...<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 10 2001, 3:56 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I doubt they would be of much benefit outside of a racing environment though. I haven't found the X brakes to be lacking using my basic rule of thumb:
"Can I lock up the front wheels at will without breaking my seat?" In the X, I always seem to run out of grip first.
That said, I wouldn't mind trying a pair of these anyway, just for interest.
Susceptability to cracking can be an issue with drilled rotors but a lot depends on how they were made.
Mark Freeman
Newcastle WA
79 1500 dual 36DCNF Autocrosser
81 1500 FI street - under restoration<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Don't know ....<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 10 2001, 11:04 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->where Holly bought their set but the average price for a set (2) of standard brake discs here in Europe is about DM 50 which equals about US-$ 25.
So I wouldn't conside this offer as ultra cheap.
Regards
Matthias<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->drilled rotors<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 11 2001, 2:03 AM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Mac,
I was recently in the Dallas, TX area visiting my dad. While there, I stopped in and met the folks at Vick's Auto. They were great and very informative. One of the things I asked them about were the slotted brake rotors that they sell. It was overwhelmingly unanimous that there only benefit was aesthetics. They told me that they don't even run them on their race cars. They use the stock (cheap) rotors that they sell for I believe around $15.00 each. They told me that there was no gained benefit, so why waste the money?
Hope this helps in your decision.
Greg
'76 X and '80 Parts car<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Let me cast vote # 4...<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 11 2001, 5:34 AM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I have never used the slotted rotors so I must base my X-perience on what I have used.
1. As one other writer said... I run outta tire before I run outta brake... and I play pretty rough on the street, in the hills, and in LA traffic.
2. The ENTIRE system is the same as used on the much heavier 124... Hmmmmmmm!
3. As with one other writer... The MOST I have paid for a rotor was 16.50... So I can buy the same set of 4 for the price of 2 of the slotted.
4. If it was aesthetics I was going after... I find it still difficult to do if I gotta bend over and peer through the mag slots to see them... I'd spend the money elsewhere.
5. As I said, with no personal background... I still think the drilled rotors would be a benefit in RACING... and as for cracking... I would assume these rotors would be replaced quite frequently anyway.
Good to see yur 'up and around'... take care,
Best Regards,
Tony Natoli
Two '79s, WHITE FANG and BLACK TOOTH
Santa Clarita, CA<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I Have em, I use em on the street and track, they make a difference. use em.<NT><!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 11 2001, 9:41 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->.<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 15px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->drilled discs, good<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 11 2001, 10:29 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 15px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I drilled mine for two reasons. 1/2 lb rotating, unsprung weight is a significant reduction. allso, in a pouring rain drilled discs start to work a little sooner than not drilled. No cracking problems, I peened each hole as recomended by Carol Smith in one of his books. I also am fairly easy on brakes.<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 30px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Drilled/Slotted and Racing<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 12 2001, 8:28 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 30px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->I have a great deal of experience with drilled and rotors on X1/9s. I have had Brembo drilled rotors on my '74 for some time. These have seen lots of track use. I also had a set of them on another car as well. These saw lots of fast street duty. I use the stock rotors on my race car.
What makes brakes work is surface area and mass. The surface area is where the friction is produced. More surface area on the rotor equals more stopping power. More mass enables the rotor to absorb more heat and because the function of the brakes is to turn motion energy to heat engery, the ability of the rotor to absorb heat is of the utmost importance. Drilling or slotting the rotors reduces both surface area and mass. Therefore, they reduce brake performance.
The reason for drilling rotors is either: 1) to allow for airflow on a vented rotor (X1/9 rotors are not vented) or 2) reduce mass. On some racing applications, the rotors are oversized so they can be drilled for lightness and the resulting mass and surface area is adequate for the weight and performance of the vehicle. The reason for this is a larger diameter rotor has more mechanical advantage over the tire. Also the surface area and mass is significantly increased from a small increase in diameter. Therefore, a large diameter drilled rotor produces a more effective brake package for a given weight.
A properly setup X1/9 brake system has truely amazing braking power. I use all stock components on my racecar; calipers, lines, master cylinder and rotors. The only thing that has changed are the pads, fluid and the removal of the backing plates. Last fall, John Montgomery, X1/9 owner and president of FLU (Fiat Lancia Unlimited), rode in my racecar on the road course at Talladega. The first corner we hit at full speed he nearly paniced. Afterward, his very first comment about the car was the brakes. I did over 30 laps that day hammering the brakes at every corner on every lap. They never once let me down and at the end of the day, the rotors look fine. The pads were kind of spent, but they had two seasons of autocrossing on them before getting there.
As for slotting, some brake pad compounds are designed to be used with slotted rotors. Tarox is one of these. The purpose of the slots is to remove the gasses produced by heat and friction.
As for shedding water. Water is unlikely to cling to the brake rotor. Remember it is spinning and therefore any water on the rotor would be slung off. Further more, if the brakes are being used heavily, then the water would vaporize as soon as it hit the hot rotor.
Steve
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[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 45px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->wet brakes and drilled rotors<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 12 2001, 10:48 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 45px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Steve,I'm sure you're are correct about the x brakes under racing conditions.But when cold and soaked, as when driving almost any winter day here in Seattle, the drilled rotors do give full power sooner than undrilled. Maybe the pads or rotor absorb some water that goes to vapor when the brakes are applied? both are porous to some extent.<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 30px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Some late-night engineering comments<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 13 2001, 11:23 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 30px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Hey Steve -
It's hard to counter your argument about mass and heat dissipation (your responses are always so logical, well thought out, and simple
Assuming the pads are properly matched for the given rotor type, the winner would boil down to the rotor with the highest energy/heat transfer rate to the surroundings. Peening or chamfering the drill holes to prevent cracking would decrease the friction somewhat (but might enhance the surface area for cooling).
In my opinion, drilled/slotted rotors should be an appreciable improvement for normal street driving (by increasing the friction - the "bite"). They should also be best for racing (because of the increased energy transfer to and from the rotor), as well as enabling higher-temperature operation. Rob Hill
Raleigh, NC
80 Rosso X1/9
Potenza = Velocita
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[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 45px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Some early-morning engineering assumptions<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 14 2001, 9:00 AM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 45px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->"doesn't drilling the rotor increase the co-efficient of friction?"
In your example of the vegetable grater it does. The vegetable grater depends on the edges of the holes to bite into the soft vegetable for resistance. The result is a very high wear rate! Which is of course what the vegetable grater is desiged to do. The other thing it does in increase the clamping pressure. By reducing surface area the force applied by the caliper piston is distributed over a smaller surface area of the drilled rotor and pad. The higher pressure exerted over a smaller area increases the wear rate and heat generated. The increase in heat generated will also increase the wear on the surface of the pad and rotor.
For a moment, lets return to the vegetable grater. Consider what the vegetable grater does to the vegetable (or your hand!) and then think of that happening to your brake pad!!! Your brake pads will wear out quickly.
Now lets make another comparison. A racing slick to a snow tire. The reason the racing slick is slick is two fold; one, maximize the contact patch of the tire. And two, minimize wear and heat buildup. The reason the snow tire has knobs and groves is to cut into to soft snow (a high friction co-efficient). In doing so the snow has a very high wear rate! But wouldn't running the snow tire on dry pavement out perform the slick? It has a higher psi for a given load. It allows airflow around the tread blocks to cool them. The agressive tread pattern will have a high friction co-efficient. (The same argument for the drilled rotor right?) In practice, the snow tire cannot absorb the heat generated by the high friction co-efficient and the resulting wear rate will quickly ruin the tire.
A key point to remember in this argument is the design of the rotor. Drilled rotors are also vented. This means the rotor has two friction surfaces (a front and back) with an air gap in between. The air gap is bridged by vanes which structually connect the two friction surfaces and act as an air pump. As the rotor spins, air is drawn in through the holes and pumped out along the edge by the vanes. This is where the airflow comes from. The back side of the friction surface and the vanes provide for a great deal of surface area to be contacted by the flow of air. Simply drilling through a solid rotor (as is the case in the X rotors) does not provide for airflow as is the case in a vented rotor. Drilling through the solid rotor only reduces the surface area because removes more area on the surface of the rotor than it gains on the walls of the holes. Finally, there is no mechanism to remove the heat that builds up in the holes because there is no airflow through the holes.
Slotting the surface of the rotor does not provide for airflow over the rotor as the slots are too small to have any influence. The slotting allows an escape path for the gasses that build up between the pad and rotor and actually cause the pad to "hydroplane" the same way a tire does on water. Again, slotting should only be used with pads that require it.
Brake pads and rotors are designed for a balance of long life and performance. A manufacturer of street cars wants his brakes to provide adequate perfomance with long life. Drilling or slotting the rotors will reduce the life of both components. Notice that few production cars use drilled or slotted rotors and those that due have very large diameter rotors to make up for the loss in surface area and mass. In racing applications, the battle is always to combat heat. Overheating the brakes will cause them to wear quickly and possibly wear out before the end of the race. Airflow is critical in this application. I am sure you have seen the massive brake ducts on most racing cars. Brake rotors are sized as large as possbile with drilling and venting to provide for as much airflow as possible.
Now lets go back to the rotors on an X1/9. The solid rotor (like our slick in a previous example) provides for as much surface area to contact the pad as possible and also for as much mass as possible to absorb the heat produced. The low friction co-efficient is offset by the increase in contact area. Drilling the solid rotor will increase the friction co-efficient, but the pad life will suffer. In addition, it may provide for more braking power on a single stop, but then requires more time to cool before maximum performance will return.
In practice, on the street, drilled rotors will wear the pads and rotors faster than solid rotors. They may also provide a slight improvement in absolute stopping power for a single stop. In competition use, drilled rotors will wear the pads and rotors much faster than solid rotors. They will also reduce braking performance and life as the rotors and pads will be forced to operatate at a higher temperature and have less surface area to absorb energy and dissapate heat.
The ideal performance brake package is a large diameter rotor, to provide for mechanical advantage over the tire and a lot of mass to absorb heat, that is vented and drilled to provide for airflow to dissapate heat. The large diameter provides for enough additional mass that the mass lost through drilling does not degrade the heat absorbtion to the point of performance loss. The pad is compounded hard enough to survive the wear resulting from the friction co-efficent for the duration of the race.
The ideal street brake package is much the same, with the exception that the rotors not be drilled so as to provide for long service life and low cost to manufacture.
Steve
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[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 60px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->Hey guy's listen to Steve, How meany championsips has evry one else won? <NT><!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 14 2001, 10:44 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 60px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->it makes sence.<!-- google_ad_section_end -->
[/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD vAlign=top align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial] [/FONT]</TD><TD vAlign=top noWrap align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]
[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 60px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->No argument, you make a good case. But aren't you saying<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 15 2001, 10:41 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 60px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->the x's brakes have more heat storage than needed for street use?(They work well with no major modification under hard racing use) In street use, doesn't it seem worth trading some heat storage( mass)for better acceleration,ride, and roadholding? Street and race conditions are different.<!-- google_ad_section_end -->
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[FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD style="PADDING-LEFT: 75px" vAlign=top><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD align=left>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->X Brakes<!-- google_ad_section_end -->
[/FONT][FONT=Trebuchet MS, Verdana, Tahoma, Arial][/FONT]</TD><TD vAlign=top align=right>[FONT=Trebuchet MS, Verdana, Tahoma, Arial]July 17 2001, 5:23 PM [/FONT]</TD></TR></TBODY></TABLE><TABLE cellSpacing=0 cellPadding=1 width="100%" border=0><TBODY><TR><TD style="PADDING-LEFT: 75px">
[FONT=Trebuchet MS, Verdana, Tahoma, Arial]<!-- google_ad_section_start -->You make a good point, but there are two things to remember: 1st, the X is an enthusiast car and Fiat knows its customers drive their cars hard. So having some extra brake capacity is a good thing. 2nd, It was quicker, easier and cheaper to use the existing brake packages from its parts bin (124/128/etc...) than to design and manufacture an entirely new system for a realatively low production car.
Steve
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