MAZDA Hard Chrome and Soft Nitriding
 

I hope this solves some problems and helps on decision making money savings on the long run. http://jhbperformance.com/downloads/jhb-tech01oem.pdf

The article essentially argues that rotor housings and side housings undergo special treatment from the factory to improve life and sealing capability which the aftermarket cannot reproduce. Re-chroming services cannot reproduce special factory coatings and the patterns in the chrome (pores and channels) which are designed to reduce friction and the resulting chatter marks, chrome flaking, and scratching.

The top layer of material in the side housings contain a special coating from the factory that increases hardness and reduces friction, and when you lap the irons you lose that too.

It's pretty interesting, but it really needs to cite its sources. Where are those diagrams coming from? Who wrote the thing?

so what about the fact mazdatrix and racingbeat both lapp irons for rebuilds, but only offer a resurfacing? does this mean all the lapped irons mazdatrix sells are potentialy 150 hour motors?

I havnt seen anyone succesfully rechrome rotor housings.


Side plates are easy done.
Machining them is one thing.
they must be rehardened.
Their is a place in aus that does it. They bake for 48 hours.
I have done this process now a few times and it comes out excellent and seems to be as tuff as the mazda surface. My current engine has ground and rehardened plates. when it come apart ill put an update.
Has been running 30psi for some time now and boost usually acclerates side plate wear so if something was to go wrong, it would do it in this particular engine.

As I understand it as long as you only lap off 3-4 thousands of an inch you retain (some of) the hardened coating. Any more and you lose the coating, and if you really go crazy you don't leave room for the coolant seals.

could you not mill out the coolant passages also? say you had to take off .05" could you not simply take the same amount out of the coolant passages and then have the surface rehardened?

Time bomb why NOT...
 

Im glad You can READ

to mi understanding pineaple racing dose but sounds like that 150k miles not hours thats what you meant ?

After all that trouble why not just buy new irons? They're not that expensive, all things considered. Besides, I'd be willing to bet that the 'refurbished' irons wouldn't last anywhere near as long as new ones.

Also, irons don't wear like rotor housings, so there are usually good low mileage ones available on the used parts market......

sorta, the pre rx7 pre nitride housing life is way way shorter than the coated ones. its kind of implied in that paper, but if you ask people who had experience building pre rx7 engines they will tell you you HAVE to lap the plates when the motor is apart.