It may be easier to leave a blank face and leave other to work out
their
own
requirements.
I looked at your drawings Paul and it would seem that their is a
seal on
the
bellhousing/plate, as
there is a recess for some reason.
My own PSRU will have a flange like the bellhousing, unlike Tracy's
which
bolt
right through,
although there would be some advantages to that - thinking out loud
!
George (down under)
I think the blank face is the best approach. Make that part of it
about
13 MM thick so there is enough meat to machine it out for Tracy's
input
shaft oil seal.
Paul Lamar
****************************************************************************
****
Hi George;
Been keeping a close eye on your progress...Looks pretty good, and VERY
promising!!
Count on me buying one!!
Okay, heres my suggestion:
If you're planning on offering the Bell Housing for multiple PSRU
adaptability,
which is the smart way to go, then the question becomes should you offer
it as
a Virgin Casting (Un-Machined) or Partially Machined.....Obviously the
best of
both worlds would be the latter, providing you watch the $$ cost.
So the Skinny should be:
VIRGIN CASTING:
-Allow generous thickness on the PSRU's mounting surface.
-A center line referenced casted in place 2" dia hole should be provided
to
give the Machinist a good rough part concentric center line point to
start
with.....Saves on shipping weight also :)
PARTIAL MACHINED CASTING:
-Engine mating surface, mounting holes & Pin locating holes should be
done.
-Facing off the Housing to length (Surface for mounting the PSRU) and a
2" dia
concentric hole should be included. This hole can later be indicated and
opened
up to whatever the custom requirements are by ANY half ass Machinist,
together
with the PSRU's mounting holes.
IMO;.....Any other type of "Special Adaptations" (Such as Tracy's
Re-Drive rear
Seal) should be dealt with an Adaptor plate.....Period.
BTW;....This Bell Housing can be utilized for Direct Drive use also as
it would
make a great platform for an extended Shaft Bearing ;-)
Hope this helps you out George.
Butch
Butch,
Thanks Mate - were singing from the same sheet of music from what your
saying.
The problem is and Paul already must realize this, is that to cast something
you need some taper on all sides to allow extraction of the pattern from the
sand.
The mounting holes are so very near the diameter of the Auto bellhousing
flywheel that this isn't possible to do a bellhousing to suite the auto
flywheel - I tried and it just won't fit. ( not with my skills anyway)
The reason it fits in the auto bellhousing is that the first section is
straight (die injection moulding) and very thin. So thin in fact they have
been known to crack in racing application (so I'm led to believe).
So my alternative is the manual ring gear on an aluminium flywheel - which
gives so much more room and allows me to beef-up that area. It may well be
why Ross went this way!?
Now my first cast may be a bit heavy, not being an engineer, I've probably
over engineered it - better to be safe than sorry.
So I figure if I need another pattern I can make it - much easier the second
time around.
I will send a photo of the pattern when it looks a bit better (filling pin
holes). You will see from the shape it will be easy to find the centre. One
you have the centre it is easy to ID the mounting holes.
I have some other small design issues which I hope to overcome as I get to
them and that's the problem of the mounting holes within the raised platform
which incorporates the starter motor. I don't know whether to incorporate a
(cut to size) tube insert or allow some solid sections within the pattern
itself -to be later drilled.
Another problem is where to put stiffeners - I still thinking about all
these issues.
How about making some suggestions when I send a photo!
George (down under)
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