resurfacing rotor housings
 

so im looking at these places that resurface rotor housings and from what I get is that they don't add any material, but they do a minimum resurface like a brake rotor?
So the apex seal springs take up the extra clearance created?
I'm curious because there is someone selling a set of housings that are resurfaced, so it caught my attention. pros and cons?
Build my next engine with good used parts or resurfaced parts?

Generally when resurfacing they are taking away a very small amount of material. So little that the housings are still within spec. If the resurfacing was done properly then they would most likely lead to a better engine than non resurfaced second hand parts. Resurfaced housings should seal and last longer since they will be smoother (tighter tolerance) than the non resurfaced!

I would personally stear clear of resurfaced housings, once the chrome becomes thin it is a slippery slope to flaking chrome

Definitely be wary of too much refinishing but if you can get proof that the chrome thickness wasn't taken down much and its still within Mazda specs it should be fine. But Chris is right. Cracking chrome is game over. I haven't seen it on housings personally but I have plenty of experiences with chrome platted bearings. They are trash as soon as the chrome is compromised.

Mazda's spec was to throw it in the garbage can... just saying, there isn't a "spec" for this.

Oh haha. I mean there was a design spec at one point but I guess that's not public info. I don't actually have any experience with resurfaced housings so I was only speaking theoretically. I did come across this thread which was an interesting read but would make me agree that non resurfaced would be better. http://rotary carclub .com/rotary_forum/showthread.php?t=12967
People seem to be having luck with it but engine lifespan is for sure less considering the chrome is the original material choice for the apex seals to be in contact with.

so after doing some more detailed research I agree that resurfaced housings are a no no! Sorry for giving an answer before doing quite enough research. Essentially what I found is that the layer of chrome and nitrated cast iron (underneath the chrome) is so thin (much thinner than i thought!) that any machining would likely leave you with non hardened cast iron as a housings surface. Sorry again to cause confusion.

I was almost thinking about higher pressure apex springs

Don't worry about the larger gap. Its really minimal. The concern is more that your apex seals will be rubbing on much softer material then they should. After any significant resurfacing process you are left with untreated cast iron which is a much softer material than the hard chrome that the housings are surfaced with from the factory. The friction between apex seals and the housing will also be greater with the resurfaced housing. This means lower seal and housing life. This is all assuming that the surfaces haven't been treated after the resurface though.

If rotor housing have slight scratching or chatter marks, they are a candidate for resurfacing. The process should be a very light hone and it doesn't add any material back. Any housings that have chrome flaking or gouges from apex seal debris are garbage in my opinion. I have a local place that does it for me.

Can you get some specific information from them as to how much they take off?

a few thousandths is all i take off.