Can you easily create brake rotors out of a chunk of cast iron? If you can, is there anything to be aware of in the machining process?
Can you easily create brake rotors out of a chunk of cast iron? If you can, is there anything to be aware of in the machining process?
Why cast iron? If you are going to do all the work, use aluminum.
What are you trying to accomplish besides possible brake failure due to learning curve?
Machining is easy but messy. CI is very brittle and I don't know how it dissipates heat compared to other materials.
Dan
No not easily.
Make sure you have the right type of CI
CI is abrasive and hard on tool edges and machine ways. The dust gets everywhere and it's hard on your lungs too.
It is easy to machine for all that.
I think it's more stable under heat than steel, which is why it's used for brakes. Could be wrong on this one.
Finally, find a brake out there you can adapt rather than make one. Even extensive machining on an existing rotor would be preferable, IMO.
-James
jamscal wrote: Finally, find a brake out there you can adapt rather than make one. Even extensive machining on an existing rotor would be preferable, IMO. -James
Like he said.
If you don't know exactly what you're doing, I would go with the modify another one or think of something else. My friend was riding a Harley drag bike (although not much on the bike was Harley, if anything at all) that he just bought. It had custom made brake disks. On the 3rd pass, both front and rear disks exploded as he tried to put the brakes on at like 180 MPH at a "short" track. He stepped off the bike at 180.
You can find all kinds of rotors at Coleman Racing (NFI), and many other sites as well. Will be much cheaper and easier.
In reply to Dr. Hess:
Ouch. Quite literally, I guess.
Speaking as someone who spends both their home and work hours in close proximity to a machine shop:
A nearly endless array of brake rotors exist already, and machining the existing top-hats, interchanging calipers, designing caliper relocation plates or heading to the pick-and-pull to get different hubs or 3rd members are all ways to take advantage of this.
Assuming the rotor that's being discussed is a small one, since it wouldn't have any cast-in ventilation, you'd be looking at buying some pretty high quality cast iron round stock (you'd start with round as opposed to plate to have favorable grain structure alignment) from someone like Dura Bar. I've never bought CI rounds anywhere near that large but what I have bought has been very expensive. As for what grade to use a good starting point is SAE brief on iron rotors.
Most motorcycles and 4-wheelers use stainless steel rotors - 320mm on most modern sport bikes with radially mounted monobloc calipers - but they're designed to shed heat from slowing 650 pounds of rider and bike. They'll run orange and park blue if used on much of a car.
In summation, it's generally best to exhaust the available supply of wheels before setting to inventing new ones.
(Another thought: Speedway Supply has stuff for the left turn only crowd including dwarf, bandolero and fractional midget cars. Look there too)
Yeah, that one hurt a bit. He actually (at 180 MPH), layed the bike on it's side, then stepped off kinda feet first, sliding on his back. He, of course, had full safety gear on. He broke a bone in his ankle. Sorry, I don't know which one. He limped around on it for a couple days, then had it xrayed, oh-look, broke, and had it fixed (pinned, I think.)
Cast iron is used in brake rotors because of its thermal properties. I was looking at grade 500 grey cast iron since it features some of the best thermal properties. I may end up just turning to HRP World for some custom rotors.
NOHOME wrote: Why cast iron? If you are going to do all the work, use aluminum. What are you trying to accomplish besides possible brake failure due to learning curve?
Aluminium rotors?
m4ff3w wrote:NOHOME wrote: Why cast iron? If you are going to do all the work, use aluminum. What are you trying to accomplish besides possible brake failure due to learning curve?Aluminium rotors?
Original Lotus Elise had Aluminium metal matrix rotors, first in production I belive. Didn't last long though.
What is the application? Custom rotors should be a last ditch option unless you just want to throw money at it.
I'd bet $100 that NAPA has something on the shelf that will work for you with a little modification.
2002maniac wrote: What is the application? Custom rotors should be a last ditch option unless you just want to throw money at it. I'd bet $100 that NAPA has something on the shelf that will work for you with a little modification.
w3rd
Or go to a pull a part and grab every rotor (don't forget to label it) that you think may work and pay your $30 for a truckbed full of rotors.
It is for a formula SAE car.
In reply to 96DXCivic:
Then you should be looking at motorcycle rotors. Are you looking at running a 3 or 4 rotor setup?
96DXCivic wrote: Cast iron is used in brake rotors because of its thermal properties. I was looking at grade 500 grey cast iron since it features some of the best thermal properties. I may end up just turning to HRP World for some custom rotors.
IF you want to get custom ones contact Coleman Machine/Racing or Wilwood. They most likely make the ones HRP sells. HRP justs sells racing parts, they don't make them.Coleman makes their rotors!
oops, engage brain before reply. 
The mental image came up with "Caliper" even though the OP stated rotor. I cant even imagine buying a chunk of cast iron big enough to machine a rotor of any size. That's where the "Cast" part of "Cast Iron" comes into the picture!
Also, I don't see quite as much risk doing a rotor.
The "custom made" rotors (disks) that came with the bike are what exploded on my friend -> NO BRAKES at 180, short track and a net that he figgered would kill him if it hit it. They were Wilwood calipers, if I recall. They did fine.
jimbbski wrote:96DXCivic wrote: Cast iron is used in brake rotors because of its thermal properties. I was looking at grade 500 grey cast iron since it features some of the best thermal properties. I may end up just turning to HRP World for some custom rotors.IF you want to get custom ones contact Coleman Machine/Racing or Wilwood. They most likely make the ones HRP sells. HRP justs sells racing parts, they don't make them.Coleman makes their rotors!
Thanks for the heads up. I will look at that.
96DXCivic wrote: It is for a formula SAE car.
we made our rear rotor (inboard on the diff) by just cutting a cast iron sheet with a water jet.
you can probably find hats that will adapt to your desired bolt pattern and make your rotors that way.
The fronts were Wilwood IIRC, so we didnt bother with them.
For a FSAE car, use kart brakes. Call Shockwave or Margay.
We are making our own rotor hats. They are already designed as floating rotors.
Water jet is what your looking for then.. IIRC the team I was with just did up a file and ordered from some outfit in town (was with OSU). BE SURE TO GET SPARES WHILE YOUR AT IT! (our diff came adrift testing the night before competition and all hell broke loose)
Gonna be well worth it vs the time/ tools/ mess of DIY. you can even spec in crossdrilling if you want to. You will have to look at what your calipers can get away with, but we were somewhere between 1/4 and 1/8th of an inch thickness for ours.
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