Paul, What material or can you suggest a vendor to make some custom
Apex seals for use in a new design?

Regards, Norman Parmley

What kind of new design ?


Paul Lamar

    Hi!: from my readings, I'd say that the type of material that would fit well for any type of seals, apex seals or side seals, is mandated also by the material in the epitrochoid or inner surface covering, not all materials are compatible, the phenomenon of galvanic corrosion may take place with some combinations of apex/housing materials, SAE published recently a book on Galvanic corrosion, this may be one of the reason some point that a Wankel engine should be turned every now and then, even when not on fuel and ignition, and that by leaving it standing still for a long time may cause serious damages in the interior side of housing and other parts inside, and from the early times and the last NSU times, Chrome alloys or  Nickasil was used (patent accessible with Citroen as applicant, search words ' friction reducing surface coverage' or something like, period 1960-177).

Mazda in 1987 introduced a Molybdenum-Chrome plating, and Suzuki Re-5 used the covering procedures described in the Canadian patents by Alfred P. Grazen, combined with Ferro-tic alloy apex seals, if a wrong seal/housing working surface is chosen, the Rotor when turning will tear off parts of surface covering, I guess this was that early Wankel engineers called 'devil's scrapes', or just an accelerated surface and seal wear may result if the apex seals material is too hard compared to the trochoid surface covering.

I have no more ideas about where to search for a good combination of apex seals/trochoid materials, but Wankel engine producers, when introducing a change in the models they sold, usually indicated specifically which improvements were introduced, and probably any change in materials of apex seals and housing's working surface that improved results would have been described in the advertising or specialized press and technical publications around the dates of its introduction to the market.
    Thanks for your kind attention, best regards. Good luck.

J G A

For the Wankel rotary silicon nitride ceramic makes the best seals.

Projected life is 20,000 hours.

Paul Lamar