Tom Webber wrote:

Ok dumb question coming.  Is the nitride surface of the side
housings harder then hard chrome?  Has anyone had the side housings
lapped then hard chromed?  Is this not a good idea?  Any response is
welcome.  Tom Webber

Howdy Tom,

The nitrided side housings are VERY hard.  How much harder or
softer than hard chrome plateing I cannot say,  but they are very
durable,  which is the main issue.

The other advantage of nitriding the side housings is that the
surface is microporous and holds oil quite well,  which greatly the
aids lubrication of the side and il control seals.  So why try to re-
invent the wheel?

I have had great success for over 25 years nitirding the early twin
dizzy end plates.  Longevity increases 5 fold,  especially in race
engines (We currently still race a 10A PP in the under 2Litrrre
class which regularly gets spun to 10,400)..

I have rebuilt the same race engines (ours and others) 3 or 4
seasons in a row using the same side housings without needing to
resurface them.

Once the grroove on the minor axis gets too deep, a quick surface
grind by someone who knows what they are doing,  followed by
nitiding,  and then a hand lap (using two housing faces together
with some lapping paste) will give you an ultraflat surface that is
beautifully micro-porous,  and wears just about as good as
anything I've seen.

The disadvantage of chromeplating would be that differential heat
buildup could cause the chrome plating to come off.  Moreover,  the
early 10A R100 rotaries had hardened sprayed surface where the
oil contrrol rings ran.  This regularly delaminated in spots and
produced clouds of blue oil smoke.

Mazda spent gazillions of yen to get their porous chrome plating to
work on the rotor houisngs,  which have a steel plate backing
insert..  I've tried to get some local guys to re-chrome rotor
housings,  but it just doesn't last.  So I can't see it being any
different with side housings.

Cheers,

Leon Promet
www.promotorsport.com.au

 
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