The picture below shows my S3 bell housing from the engine side.
I only measured the six 11.5mm diameter through holes that are used to mount the bell housing to the engine block. If you need to know the locations of any of the other holes (starter motor, bottom access plate, etc.) let me know.
For clarification purposes, I chose to number the block mounting holes from 1 to 6 (yellow numbers in photo).
Here are the results I got with a set of digital calipers (hole center to hole center):
1 to 2: 41.79
2 to 3: 146.72
3 to 4: 155.85
4 to 5: 98.72
5 to 6: 93.18
6 to 1: 295.61
1 to 3: 183.40
1 to 4: 282.65
1 to 5: 302.52
2 to 4: 261.31
2 to 5: 294.21
2 to 6: 300.42
3 to 5: 231.02
3 to 6: 282.50
4 to 6: 183.49
I'm working on plotting these values on an AutoCAD drawing, which I'm sure would be helpful to a machinist or welder trying to fabricate a bell housing for an alternate gearbox. I'll post a copy of the layout when I'm done.
thanks , greatly..i guess once you get it to autocad.. the same thing from the centre of the crank/input shaft would be great... this will help me mount it to a 2.2 ecotec motor.. cannot wait..after a few small things. a easy 185 hp and 170tq.
I arranged the block mounting holes around the input shaft. Let me know if the the data points shown in the attached file will serve your purposes, or if you need something more (or a different format). I can PM you the .dwg file that I plotted this from if you like.
I measured the inside diameter of one of my bell housings today. I ran a set of calipers all the way around, checking the results about every 5cm.
I found a very slight draft on the inside of the casting, tapering inward from the lip (see first photo), but in my opinion it was a negligible amount, and I figured you were more interested in available clearance anyway.
The ID varied from 282.15mm to 282.60mm (on the bell housing I checked) so I think a 'clear' inside diameter of 282mm is a safe assumption.
I'll check an older one I've got laying around (that doesn't have VVT sensor mounting holes) and let you know what I find, just to make sure it's in the same 282.2mm to 282.6mm range.