coatings and treatments

[rgould]

1) the factory nitrate is only about .010 deep into the sideplate surface so when you resurface a badly worn plate you cut through the original harding which leaves soft cast iron for the side seals and corner buttons to ride against.
2) the rotor does not ride against the side plate so it does not need hardening. Ceramic coating is a better choice to help keep the excessive heat on the rotor face and to help control oil temps.
3) I have been involved with cryoed brake rotors on all out race cars and for some reason they last longer than ones not cryoed so it does something good to the metal.
4) shot peening uses small steel shot like steel bbs to beat the metal surface to remove internal stresses.
5) as in any engine rebuild you have to be mindful of the clearances on all the internal parts going into the build.

[kfcpork]

i had forgotten completely about ceramic coatings, and from what i've been reading the more parts you can cryo the better. still a noob when it comes to rotary motors waiting for a few books to come in the mail so i don't sound so challenged but i think it would a good idea to wpc treat the plates after resurfacing them then nitrate them. feels like money spent in a good place for some extra insurance. as far as clearances go do people make plus sized corner seals and buttons to make up for that treatment?!? (NOOB-ISH I KNOW)

[RETed]

Originally Posted by rgould

2) the rotor does not ride against the side plate so it does not need hardening. Ceramic coating is a better choice to help keep the excessive heat on the rotor face and to help control oil temps.

Be very careful about this...
There is a right way and a wrong way for these coatings.
In general, metal sections are used to conduct heat (away).
Putting coatings on the wrong surfaces can increase (internal) heat (into the cooling and oil systems).
Mazda engineers have documented that the rotary engine oil system takes care of 1/3rd of the heat (dissipation) from the working engine.

3) I have been involved with cryoed brake rotors on all out race cars and for some reason they last longer than ones not cryoed so it does something good to the metal.

It's the conversion of martensite and austenite crystals within "steel" alloys.
http://en.wikipedia.org/wiki/Cryogenic_hardening

4) shot peening uses small steel shot like steel bbs to beat the metal surface to remove internal stresses.

You should remove the word "internal".
This is more a surface treatment, and it converts tensile stress to compressive stress.
It is also not recommended for critical clearanced surfaces.
http://en.wikipedia.org/wiki/Shot_peening


-Ted