free gearbox case

[99Super]

Interesting.
I'm using an 870423 case as the basis of my next race box. It is date stamped 12/77.
It has NO ribs at the front and just a large solid hump that would fit in the same location as the differential ribs.
I'll post a pic later...

John

[Jordan]

The material on that also looks different than one 3-rib diagonal box which is what I always thought was the "strong" box. But it could be that I live where the salty things are.

[Geoff]

Assuming all of those boxes are 870432 it would be interesting to know what the date stamp is on all those boxes.
Jordan's with 3 diagonal ribs.
SPGFTW's with 3 straight ribs.
John's with no ribs.

I also wonder what the other numbers are on the underside for each box (like 260/2 and the dollar sign...)

[DeLorean]

I have never even seen one with the straight ribs, Only diagonal, or none.

[99Super]

The "dollar sign" is the caster's mark. Kolbenschmidt. I think they make about half of our cars parts...

https://en.wikipedia.org/wiki/KSPG

I suppose they would have the info on the strongest cases, but how to find it?

And why on earth would there be so many variants of the same # case?

Perhaps the ribs, especially the diagonal, help direct the oil from the head over the trans for thermal reasons and are not for strength?


John

[Luke]

I think the whole chill cast thing has gotten a bit out of hand, and become more folklore than based on any actual functional difference. The original term that jorgen was using was kokill which derives from the Russian word кокиль. In English we just call this gravity die casting, which is one of most common types of aluminum casting used.
All of the Saab 4 speed gearbox cases I've ever seen were cast this way.
I believe Jorgen just identified the ones which the 3 diagonal ribs as the best of the lot in terms of the casting quality. Maybe thicker in some key areas; The steel mould would have only lasted for so many pours , maybe 15000 or so, so SAAB would have gone though quite a few different moulds in the course of the production of the 4 speeds.

[nkro]

Every case crack. The large case cracks like all others. The KS cases have better casting. (The threads don´t fail that easy)
Saab weld the first cases. And I think It was not so easy to weld alu in 1978, and they only used Alumasc castings for the S&R cases.

[spgftw]

Whoa, I'm way behind here!
The case is spoken for, for better or worse. I have some steering wheels to part with next, so stay tuned for the next fun update. :)
Paul

[Chouan]

I'll throw a little more fuel on this fire. I have several 4 speed ribbed cases with various part numbers...

Which is the strongest?

[Chouan]

And the one with horizontal ribs like the first one posted. Also 870423.

[Saabguy70]

I have this...1980 4 speed chillcast has 5K on it.

[Chouan]

What's the part number?