How do aluminum rotors fare versus steel? I am a bit worried about the strength and thermal capacity compared to steel.
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April 21, 2009 5:03 p.m. 96DXCivic Reader
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April 21, 2009 5:16 p.m. maroon92 SuperDork
I didn't know there was such a thing...
can't imagine aluminum holding up to the stresses...
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April 21, 2009 5:21 p.m. mel_horn HalfDork
Nor can I.
There is such a thing as composite rotors but I don't think aluminum is part of it...
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April 21, 2009 5:36 p.m. AngryCorvair Dork
there has only been one rotor i know of with aluminum brake plates, and that was on the rear of the Prowler. it was an aluminum metal-matrix composite, so there was lots of other stuff inside the molten aluminum when they were poured.
google "melting point of aluminum" and then google "rotor temperatures at sebring" and compare the results.
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April 21, 2009 5:40 p.m. Keith SuperDork
Bill Cardell at FM used to run an aluminum rotor on the back of his race bike - but that was just because he was required to have rear brakes. He never used 'em.
The classic "Minifin" for Minis is an aluminum drum, but with a steel liner.
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April 21, 2009 5:41 p.m. Tim Baxter Online Editor
The first time I forgot to replace brake pads--which I would surely do--would be the end of may aluminum rotors.
Too soft and easily damaged for a street car, too easy to melt for a track car.
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April 21, 2009 5:48 p.m. Strizzo Dork
they mentioned something on the top gear communinst car piece about using aluminum drums on the brakes of one of the cars, then mentioned that the soft aluminum sucked for braking
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April 21, 2009 6:03 p.m. Nashco SuperDork
The only aluminum brake stuff I know of is aluminum drums, but those used an iron wear surface (as long ago as the 50s and 60s in American cars IIRC). I've never seen aluminum rotors, and can't imagine aluminum would last at all with an agressive pad choice. Even iron wears fairly quickly with aggressive pads.
I hadn't seen the Prowler rotors, I'll have to read up on that for future weird automotive trivia.
Bryce
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April 21, 2009 6:16 p.m. ignorant SuperDork
OK...
We did it on the Mini Baja car. They were 7075 T6 cut like a moutain bike rotor, We CNC'd them. We then sent the parts out for a Hard Coating from Swain Tech(http://www.swaintech.com/) It was a either a carbide hardcoat or a cermaic. It was worked. We were low speed and brakes were used little. I will say the coating was tough as hell, but those rotors lasted a race. We did run Kevlar pads, due to the fact that we never put heat into the pads. IT worked.. Would never for a real car...
The calipers were anodized red( custom sliding 2 piston) and then we cut RIT Mini Baja into the showy side with a CNC mill.
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April 21, 2009 6:51 p.m. 2002maniac New Reader
http://www.pitstopusa.com/SearchResult.aspx?CategoryID=3686
Roundy round cars use them sometimes. I know wilwood has a specific compound for aluminum rotors.
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April 21, 2009 7:01 p.m. 96DXCivic Reader
Ok. I didn't feel like it was a good idea but I saw it being kicked around by some FSAE guys.
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April 21, 2009 9:10 p.m. InigoMontoya Reader
you can do 2 piece rotors if you need big ones, AL center and then regular for the rotor piece. I know DBA makes some at a somewhat reasonable cost.
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April 21, 2009 10:20 p.m. andrave New Reader
Yeah aluminum "hat" as I often hear it called. many aftermarket "big brake kits" come this way. Can't think of a production vehicle that uses em though. I believe the mclaren f1 did...
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April 22, 2009 3:38 a.m. Wally SuperDork
2002maniac wrote:
http://www.pitstopusa.com/SearchResult.aspx?CategoryID=3686
Roundy round cars use them sometimes. I know wilwood has a specific compound for aluminum rotors.
Those rotors are for the dirt sprint cars, which like iggy's mini baja racer are more for show then use. They try to shed every possible ounce from the car, including using gun drilled titanium bolts, so if the rules require brakes they run those little alum. rotors with motorcycle size calipers.
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April 22, 2009 6:47 a.m. GhiaMonster New Reader
We made a set for FSAE and had them coated with a high friction ceramic of some kind. Pad life: 5 laps. The rotors held up great, and stopped well but they were only on the car for one night due to the fact that we need to get atleast 20 some laps out of our brakes.
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April 22, 2009 9:40 a.m. Type Q HalfDork
On the FSAE team I worked on, someone explored aluminum rotors. The conclusion was metal matrix composites like those on the Lotus Elise would work well, but not regular aluminum. This was about 1995 or so.
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April 22, 2009 9:54 a.m. Keith SuperDork
I don't think the Elise used them for more than a year or two, actually.
