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Thread: What are brake rotors made of?
11-16-2011, 03:00 PM #1
What are brake rotors made of?
Or what should I make them out of would be a better question
11-16-2011, 03:02 PM #2
Cast iron, if you mean automobile or truck brakes. Bicycle rotors may be stainless steel or something.
11-16-2011, 03:14 PM #3
Being more specific, a nodular cast iron. At least I read that somewhere in my past.
11-16-2011, 03:42 PM #4
But 'make' for what?
Airheart and others offer brake disk, drum, internal shoes, external bands, et al (mechancial and hydraulic) mass-produced as parts in sizes and ratings from electric skateboards thru Go Karts to supercars. Warner and at least one Japanese firm do the same for electromagnetic actuated - similar to auto A/C compressor clutches.
Under a hundred bucks quantity of one for a 6" or so Go Kart size that'll stop a fair sized lathe smartly with an average workholder and workpiece mass.
HP rating of twice that of the motor is a good start. Work up from there.
11-16-2011, 03:47 PM #5
11-16-2011, 04:00 PM #6
Indy Cars and F1 use carbon rotors and pads
11-16-2011, 04:05 PM #7
Thanks for the replies fellas!
I could probably order one... but i thought if I had the right material laying around I might just make it.
Its for a four wheeler, we are converting it to have tracks for snow
11-16-2011, 04:11 PM #8
35 + years ago I used to make a part not unlike a brake rotor (disc), 6off at a time - engine lathe & mill work.
From castings there's a lot more work than you first think,......... from solid there's even more - not to mention swarf.
jdj liked this post
11-16-2011, 04:16 PM #9
Not that brakes are going to have quite the same task OR effect for a tracked vehicle, but Skiddo conveyor-belt track style... or proper 'Snow Weasel' independent steerables, or ...???
Wheel long ago invented in any case, no shame in adopting whatever is known to work well.
Limy Sami liked this post
11-16-2011, 04:23 PM #10
conventional automotive brake rotors are cast from G3000 grey cast iron. These work well with a pad material designed to operate using adherent friction. Most of the European system rotors are cast from a high carbon G4000 grey cast iron. These work well with a pad designed to operate using abrasive friction, such that the rotor is sacrificial just like the pad.
Some sintered metal (motorcycle) type pads work well with steel rotors, but conventional automotive pads need a more porous material, like grey iron.
11-16-2011, 05:12 PM #11
I needed new Discs and Pads for my Vauxhall Astra recently .
Found these on Fleabay , bought and fitted a set . Double, Vented, pads included and fast Delivery by courier . Run-out when fitted not measurable . Spoke to the vendor, available for most cars .
Are there not such items available in USA prompting you to MAKE them?
11-16-2011, 05:29 PM #12
The US equivalent of that Sterling price HERE gets a new set, and down the street on walk-in, not off ePray.
Rebuilds cheaper yet.
That's why I said use whatever the donor axle is fitted for.
Now if MAKING the axles....... not even the major makers do that.
Most buy 'em in from Eaton, Dana and such .. who buy the bearings from... and disks or drums from ... yadda yadda..
Have to be a good reason to make yer own of anything in million-plus units a year volume production instead of picking up a parts catalog, a pint, and yer readin' glasses....
Or Go ogle...
11-16-2011, 09:20 PM #13
i would look at snowmobile rotors and modify them to work.to think a 600 cc sled weighs 500 plus pounds,will go 80 mph and stop on a dime if track is studded.many atv rotors fit the wheel hub bolt pattern,so finding something that works would be easy.
11-17-2011, 10:00 AM #14
Motorcycles (and maybe ATVs) use 410/416 SS. Doesn't rust, and can be held on a magnetic chuck for grinding the faces.
Made one a few years back, could almost do stoppies with it...
Laurentian liked this post
11-17-2011, 10:31 AM #15
(coming from years of working on bikes of all kinds) It might be worth it to come up with a way to mount a motorcycle style disk to the hub or axle. You can find small Jap bike calipers dirt cheap. Would be easier to find a hub-bolt pattern of an appropriate size and either fit it to the hubs you're using, or machine a hub to mount it to. Lots available, solid, vented, slotted, floating, multiple material types... Find a local bike bone yard and pick a standard bike somewhere in the 650cc range. Front brakes, some had dual disk. You'll find calipers from single piston barely an inch diameter up to 8 piston banana, definitely something that will fit your application.
Lots to designing brakes, you have to take into account the calipers you'll use, diameter, thickness, piston travel, master cylinder volume and effective stroke, etc. MUCH easier to repurpose something that engineers have already developed and tested on the road for decades. Boneyard could turn up a dual disk, dual piston caliper setup and the required master cylinder. You may need to spring for a rebuild kit, but they're on the order of $10-$20 and anyone capable of doing the rest of what you're doing could handle the rebuild. PLUS, being for a wet purpose like you're after, you could use the SS rotors from a bike and not have to worry about rust. Even if it wouldn't be structurally compromising, think about wet rust slinging on your paint...
77ironhead liked this post
11-17-2011, 09:01 PM #16
11-18-2011, 09:32 AM #17
11-18-2011, 09:59 AM #18
11-18-2011, 11:12 AM #19
It really depends on the pads... if using regular organic pads then ductile iron is a suitable choice... when using sintered metal pads there are some trace metals like lead that act as a lubricant and reduce breaking force, and low 1000 series metals are better. We just built some brake rotors for a project using sintered metal pads and 1045 steel rotors.
11-18-2011, 12:32 PM #20
Not forgetting that the whole stopping process produces a considerable thermal variation around the disc. Real hot on the working part directly under the pads and getting cooler as you go round the disc to a minimum a little before it hits the pads. Plus a radial variation from inside to outside too. Pretty effective for making the thing twist and bend if the wrong sort of, or maybe any, stresses were locked into the parent material when it was produced. Twisty discs are less than ideal if you want to stop safely.
Such effects are one reason for the modern fashion of mounting the larger sort of motorcycle disc brakes via loose(ish) bobbins so the whole thing can move more or less together rather than straining against the solid hub via the fixing bolts.