The seal holder and back plate is a simple disk with a few holes. No

problem for my NC mill. Common in auto transmissions for cars.

I agree !!

That would go for the stiffening ribs as well - a nightmare to make.

Yes they are hard to make by hand but if you have a mill wood ribs are
easy as you shim up one end of the wood and cut the draft or AKA taper.
Then glue the ribs to the rest of the pattern.

You will notice that some other PSRU with bellhousings are done in

flatter

sections - this overcomes the taper problem in adding unnecessary

weight.

Perhaps we should be considering shallower sections rather than deeper

'all

in one' sections. I think we have a good depth in the housing section

(this

is governed by the starter depth anyway) and Tracy has overcome this

problem

(in the PSRU housing) by adding tube inset sections.

Paul - make the OD of the PSRU flange no bigger than 4.75" to 5" radius,
this will miss the starter by at least .5".
That gets to about 1.5" to 1.75" to the OD of the bellhousing - that is
close enough IMOP.

Checking dimensions :_
 Width,  total approx 460mm to 470mm - 18.5" finished.

The current design has the starter (hole) up hard against the MM wall - as
we may need to lift the starter closer to the centre,( because of the new
design) this will take a little extra room - it's currently 440mm.

The rest of the dimensions you have, I believe !

The Aussie design will have a bigger PSRU section foot print on the face

of

the bellhousing - it will be approx 1.75 from the top edge and have a 1"
flange - that will spread the load as well as design so far suggested.

Perhaps (and this just a suggestion) the last section of Tracy's PSRU

could

be replaced with  a section with a bigger footprint - in an effort to

spread

the load wider over the face of the bellhousing.

No insult to Tracy, but I do see the base of the PSRU housing being the

weak

link in a design, where we are trying to mount onto a housing with

thinner

walls - it's probably fine for the 1/2" plate as this is what it was
designed around, but a wider base will spread the load better, as all of
your designs have indicated.

George (down under)

OK if you want to make two casting and bolt them together. It is more
machining work and slightly heavier. I also think it will cost more
for the foundry. It is the flexible way to go however. It will have
to have a large cutout for the starter.

Paul Lamar

The PSRU will miss the starter using these dimensions.
  George (down under)

You might be right George. People may not be ready for a one piece
PSRU/bell housing. It is probably less risky from an investment
point of view to go with just a bell housing that people can bolt
on one of Tracy's psru. Perhaps in another five years.

Back to the internal ribs. Its cheaper than two casting.

Paul Lamar
 
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