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Brake Disc Material

Discussion in 'Technical and Troubleshooting Torque' started by Brucey, Sep 23, 2005.

  1. Hi All

    Just need to confirm the grade of stainless steel typically used for discs,
    is it the 416 or 420 grade ???.

    Need to make up a couple for a project so any reply would be helpful
  2. I wouldn't recommend using a 416 stainless for brake rotors since it contains manganese sulphide designed to make it easy to machine so resistance to wear and corrosion would be poor. 420 sounds like a much better option since it can be easily hardened by heat treatment and contains 12% chromium which offers good corrosion resistance especially when the metal is hardened and polished.
  3. just melt up some of the cutlery and use that :D
  4. Why have you assume it's a martensetic grade?
  5. Just make sure it isn't plastic cutlery...
  6. Makes sense to me, a martensitic stainless is typically going to offer far better wear resistance than other grades, important if you don't want to change your rotors as often as the pads.
  7. your discs are metal?? :shock: oooooh, advanced :D
  8. Kawasaki brakes mate, I feeel for you.
  9. yeah, and the amount of damage when i fall over because i cant stop is just ridiculous without any oggy knobs :(

  10. Sorry jd, Brucey and ibast, you can have your thread back now.

    In my defence, Coconuts started it :D
  11. I'm not making an argument either way, because I don't know enough about ss discs.

    I was asking, because I had the opposite thought. I though 4xx would be too hard thus giving bad braking. It's also hard to work with. Would it also be more likely to warp?

    I would have thought 316 or 316L would be the place to start, if you can get them in plate.

    I don't know either way. I'm just interested where the technology stands on this one.
  12. Austenitic (304 & 316) will not disipate heat at the required rate and also will move around too much not, stable at temp etc and as mentioned above need some bite to the surface
  13. 316 would be no good for high-performance rotors since exposure to heat greatly reduces it's corrosion resistance. 316L offers better corrosion resistance but compared to a 420 grade stainless it has a much higher thermal exapnsion coefficient, higher density, poor thermal conductivity and greatly reduced Rockwell B hardness. So yes 420 is harder to work with but is actually less likely to warp and offers better heat dissipation, the quality of braking will depend greatly on the friction material used. Incidentally there's a good site on the net that lists the properties of various metals and other engineering materials here:
  14. Totally off the topic...and no use to anyone....hey Brucey...aren't you my long lost Brother?! :D
  15. No I dont think so :eek: ??? why do you ask ??? hope you dont need cheap discs cause by the time i finish this set they will be very very very expensive.

    These are replacing a set of brembo 280mm cast iron discs on the front of my SFC Rep laverda so junking the brembos and fitting Tokiko twin piston calipers to suit a custom set of 310 dia discs. These will be drilled with 4 mm dia holes in a Shinahara cuve radiating from the centre to O/D, but not exceeding the 10% rule of surface area reduction.

    No use moding the calipers straight onto the old cast iron discs as swept area is less and circumferential speed is down.

    The old Girl still wont go as fast as the brakes will allow but what the hell its fun playing in the Garage.
  16. Isn't cast iron a better material to use for brake discs than stainless?

    (Not sure how much the difference would be however.)
  17. Grey cast iron offers some benefits, high wear resistance and good noise supression for example, however the tensile strength is vastly reduced and it is subject to brittle failure. Basically cast iron can be used but since it has a higher density and more of it needs to be used the weight and thickness of the rotors would be significantly increased.
  18. JD bang on the money min thickness brembo disc =5.5 mm SS = 4.5 mm approx weight saving per disc is around 600 gr or 1.2 kilo in unsprung weight, also by using smaller swept area = more material removal
  19. er..again off the topic....brucey...you live in Malvern...so does my brother....you have exactly the same bikes as my brother.....so doesn't the initials in my ID look familiar?? How about my bike? Would it help if I told you my bike is yellow and black...just like your sisters...and I too live in the west...just like your sister...! :D :D
  20. Perhaps I'm just getting confused with other iron discs.

    I seem to live my whole life in an ethereal cloud of confusability.

    *sigh* Must be the BM, yes I'll blame the BM. After all everybody else does and it probably is the BM's fault after all...

    shut up nearly, must ... stop .... yammering ...
    My other half is always moaning about my whittering too.