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Discussion Starter #1
On the blueprint for the chassis dimensions there's a dimension "I"- 82mm from the reference line down to the holes for the rear gearbox mount. There's then another dimension "J" - 3mm.

On the scanned PDF document I can't make out what's going on. These holes are obviously different in height by 3mm front to back but I can't work out which is lower and which holes are 82mm down.

The plan view on that PDF shows dimension "W" referencing the rear hole of the gearbox mount which suggests that "I" should reference the same hole (the rear) but the dimension is placed to the left of the gearbox which tends to suggest it is in fact referencing the front hole (not an iron clad drafting rule but relevant, if it was me I would have placed it to the right next to the hole I was controlling).

Does anyone have the original drawing which may be a little clearer?

Is 82 referencing the front holes or the rear and which way is the 3mm dim going?

I'm working on some plans for a laser cuttable chassis jig that I will post here when I'm done in case anyones wants to make their own body Jig.

Thanks, Andy.
 

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Discussion Starter #2
Hmm, more confusion on Section BB-BB. Dims "r" and "q" seem to be around the wrong way and when I check the other dimensions against the chassis plate that connects to these points some numbers don't add up.

I measure the height difference in of the outer hole with the two inner holes as about 11- 12mm on the plate. The chassis blueprint is very vague in this area and nothing adds up to hole height difference close to what I can see on my part that should mate up here. I think the confusion arisess from the plate being on about a 3mm slant like the gearbox mount but it's impossible to resolve with confidence from this drawing.

There are also extra measurements that seem to reference imaginary lines of no apparent significance. "m" "o" "p" "t" "u" and "v". The line between "p" and "t" is the centreline of the car. The other two mysterious vertical lines are both 250mm from the centre to the left and right but their purpose escapes me.

I'm quickly losing confidence in this drawing, is there another reference for these chassis dimensions?

Regards
A.
 

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Might be easier if you post a copy or link to the document you are referencing.
 

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Discussion Starter #4
My bad, I'm refering to the chassis PDF at the start of this forum. I think it's from the Cardisc CD but I have seen two different drawings both from the CD I think. here

and here - http://www.alfabb.com/bb/forums/attachments/gt-1963-1977/152171d1253412873-new-74-gtv-yikes-69-gtv-body-dimensions.jpg

I think the above image is from the 74 CD which might be a revised edition of the PDF on the sticky. Does anyone have a clearer copy of this, the rescan is impossible to read.

I also found a pic from the AH website showing the plate in question. Their's appears quite flat but I believe the drawing on the PDF is suggesting that the plate should be angled by about 3mm??
 

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There's a clearer copy of it on page 16 of following Alfa Body manual provided by Osso etc., along with a host of other very useful manuals, information and diagrams.

http://www.duettoinfo.com/alfa_romeo_duetto/shop/1570.pdf

Be great to see your jig plans when complete, I'd like to check my car as I rebuild her.
 

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Discussion Starter #6
No worries Craig. I'm planning on something a bit lighter than the AH jig shown above.

There are two directions I can take -
1. A holding jig, this assumes the body is straight and just "holds" the chassis while panels are removed. Or
2. A metrology jig which assumes the chassis may be bent and can determine where the problems lie. The metrology jig will need plates positioned away from the panel work (about an inch) and utilises sliding pins that get pushed forward to engage in critical reference holes. The metrology jig centre reference will be the area that I'm asking about so it needs to be perfect.

There may be a way I can create both with some adapters but I'll have to think about that.

The spider and the coupe have different wheelbase and the US versions have the gearbox mount setback as well so will try to accommodate all that.

I also want it collapsible so it doesn't take up space went not in use.
 
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