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Lapping and re-nitriding plates

 
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Wed Dec 28, 2005 3:42 pm    Post subject: Lapping and re-nitriding plates Reply with quote

I just wanted to show everybody what lapped and re-nitrided plates look like. Lapping is a process of grinding the side housings (aka "plates") flat, getting rid of all the seal ruts and other wear. Nitriding is a surface hardening process. Since 1979, all the plates come nitrided from the factory, so they wear more slowly, but if you lap the plates some of that hardening is removed. Re-nitriding the plates is a good idea for an engine you really want to last. Our nitride process is actually a dip, rather than the factory spray-on coating, so our's coats all surfaces, which results in a nice appearance and resists oxidation.



Lapping is not something you can just have done anywhere. While many places do lapping, the demanding tolerances of flatness and parallelism of a rotary engine is beyond the capability of most facilities. Likewise, nitride coating is not as simple as just having it done. There are many varieties of the process, both in terms of material and application, and without the "secret" more harm than good can be done.

A properly lapped and re-nitrided plate is as good, if not better, than a brand new factory part, provided all the other specs are good. Nitriding does not add to the thickness of the part.

There is another re-surfacing process available as well. Ceramic coating can be applied to the plates, which not only reduces wear but can also fill in minor wear, resulting in a truer surface. Of course, you can still have a plate lapped to make it perfect before ceramic coating, as well. There is only one company we trust for ceramic coating of rotary engine parts: JHB Performance, in Canada. Sorry, I don't have any pictures of ceramic coated plates but the visual effect is so subtle, you probably could not tell the difference with that of an ordinary plate. Ceramic coating does nominally add thickness to the plates, unlike nitriding.
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Blake Qualley
Pineapple Racing, Inc.
(503) 233-3878
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jptg



Joined: 25 Jul 2005
Posts: 66
Location: CA

PostPosted: Thu Dec 29, 2005 11:02 pm    Post subject: Reply with quote

Who does that and what is the price?
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Fri Dec 30, 2005 1:24 pm    Post subject: Reply with quote

jptg wrote:
Who does that and what is the price?


Lapping is $240 for a set of plates (4-surfaces). '79-'85 (RX-7s) can be taken down about 0.004 before you take off too much factory nitriding. '86+ are limited to about 0.003 before you run into problems with the coolant o-ring groove depth.

Re-nitriding we offer for $350 for a set of plates (2-rotor motors only, of course).

There are some other reputable places that do lapping, like Racing Beat, but I can't stress strongly enough that you cannot trust your local lapping place because they are set up for piston engines. They don't typically have the ability, knowledge or motivation to get good results on a rotary engine. The usual outcome is that it will come out nice and flat but the sides will not be parallel, so the engine turns into a banana...perhaps far too little to see with the eye but the engine will eat up bearings and there is nothing you can do about it.

For re-nitriding, I am not aware of any other company that has found the secret formula required for good results, so I'd say we're the only game in town.

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Blake Qualley
Pineapple Racing
(503) 233-3878
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Pineapple Racing, Inc.
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sorrow



Joined: 02 Dec 2005
Posts: 5

PostPosted: Tue Mar 28, 2006 7:56 pm    Post subject: Reply with quote

Wow thanks for posting that up with an example of a piece.
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jptg



Joined: 25 Jul 2005
Posts: 66
Location: CA

PostPosted: Wed Apr 12, 2006 10:49 pm    Post subject: Re lapping the plates Reply with quote

Relapping would be seperate from re nitring the plates right? Or the renitring would include the relapping of the plate?
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