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Brian,
This came up some time ago (maybe years ago), and it may have been Bill who
explained that a thinner flat pate would warp under the load of the apex/ side
seals. I believe Richard Sohn's concept to be the best approach in regard
to this and his cast iron plate is quite thick in places to maintain
it's shape, this is married to an aluminium plate with O ring to separate
the oil and water areas. I did the research on this concept and found it wasn't
quite as light as I would like - no disrespect to Richards design.
It wasn't until I heard about the chrome molly sandwich housing and the
weigh of it, was I convinced of the approach in regard to weight savings
and wear surface reliability. BTW the CM isn't sandwiched to any aluminium
- it's all CM. The question is how do you manufacture such an item, not
possible to weld on the inside, not to mention warping, so furnace brazing in
one operation is the answer. The brazing paste is applied to the contact
surfaces, clamped to hold it's shape and then it's placed in an oven. How
the hell they hold all those pieces in place beats me , maybe some
things have to be tacked in place prior to assembly - I'm still pondering the
process.
What stops the thin CM from warping is all the little pieces(channel
walls) that guide the water flow, and the thicker centre section,
which are brazed to both sides of housing - as in the cast housing.
Hope that helps.
George (down under)
Maybe having provisions for mounting on the front cover of the engine
would avoid conflicts with the exhaust system, and would lessen the amount of
mounting tubes/weight needed.
I hate to sound like I'm pontificating here, but with all this talk of
aluminum side and middle housings with a nitrided wear surface, has
anyone thought about the minimum thickness of a steel wear plate to avoid
warping due to heating? The reason I ask is that I was thinking that in order
to have aluminum side housings, a sandwich of wear plates with the rest of the
side plate made from aluminum might work without brazing the steel to the
aluminum, if brazing is even possible. Instead of brazing, O-rings like the
water jacket o-rings might be incorporated. Just a thought.
My RV-4 is 1090 lbs, heavier than I'd like. That's about 230 lbs heavier
than the Hatch/Beckham Powersport RV-4 at around 865 lbs, if I recall
correctly.
Brian trubee
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