GTcarz - Automotive forums for cars & trucks. - Turning Rotors: a case study...

It took you 12 days to come up with your lame-ass text book reply. Yet you
still don't get it - you're trying to argue a point that many people have
already demonstrated to you that you are wrong about. I can't be bothered to
repeat their - and my - valid examples and explanations. Perhaps if you took
the time to review the threads in this post and you might begin to
understand what I mean. I doubt it, but you never know. As I said, you ARE
the one.

"jim beam" <nospam@example.net> wrote in message
news:icSdnRvqXdKE4ineRVn-pg@speakeasy.net...
> doug wrote:
>> "jim beam" <nospam@example.net> wrote in message
>> news:W5edneEaDO3cKS_enZ2dnUVZ_v6dnZ2d@speakeasy.ne t...
>>
>>>doug wrote:
>>>
>>>>>sorry - unless this disk has been operated well into red heat, you're
>>>>>not going to get much change in microstructure. you can however have
>>>>>problems with a bad disk if it was not heat treated properly after
>>>>>casting. when operated hot, /that/ disk will distort. more likely is
>>>>>that there are simply different cooling rates on different parts of the
>>>>>disk leading to local temporary distortion. that shouldn't happen on a
>>>>>disk of sufficient thickness and whose internal vanes have not lost too
>>>>>much material through rust.
>>>>
>>>>
>>>>Your opinion and a dollar will get you a cup of coffee. That's all it's
>>>>worth . Repeated heating and cooling cycles will definitely change the
>>>>distribution of carbon atoms in an iron matrix - and it doesn't have to
>>>>be "red" hot. The temperatures created by the crappy pads used by GM did
>>>>the job in less than 15,000 miles.
>>>
>>>diffusion, the migration of carbon atoms in the iron matrix, happens
>>>well below red heat. but /significant/ diffusion, recrystallization,
>>>graphite flake/nodule growth, or other phase changes, doesn't. and if
>>>you're trying to argue that a brake disk is martensitic, you need to
>>>think again.
>>>
>>>if your gm disk warps in 15k, you need to consider other factors. for
>>>honda, elastic distortion caused by incorrect wheel lug torquing has a
>>>huge influence. but if it's the disk alone, things like bad
>>>post-casting heat treatments, uneven material thickness, etc. can
>>>influence whether a disk stays true at high temperatures. the most
>>>likely item is cutting corners on heat treatment and reducing heat soak
>>>time.
>>>
>>>my money's on incorrect lug torquing.
>>>
>>>
>>>>>my experience is that the disk cutting process is far from perfect -
>>>>>those cutting machines see heavy usage, and you can mount the same disk
>>>>>up a dozen times and get 13 different centers.
>>>>>
>>>>
>>>>If that's your experience, that's too bad. You need to find a better
>>>>technician, or learn to do it yourself.
>>>
>>>i was a vehicle mechanic for 5 years and also have a materials degree.
>>>is that good enough?
>>>
>>
>>
>> Apparently not - it hasn't helped you to do the job correctly. Like I
>> said before, there's one in every group. Although Dave Kelsen may once
>> again take issue with that.
>
> so why don't you make a technical rebuttal? share your superior
> knowledge.