Blueprint discrepancies?

[Willem Fick]

Hi guys,

I am trying to do some work on my 1970T, but discovered some discrepancies in the set of Porsche blueprints I am working from.

I am essentially trying to accurately position the front torsion bar mounts but am getting conflicting information from my blueprints.

As per the first two images you'll see that the distance between the middlemost holes of the mounts should be 656mm. In conjunction with that, the distance between the inboard pair should be 565.5mm, allegedly resulting in a lateral angle of 12 degrees across the width of each mount. If using the dimensions as staded above, there basically isn't a snowball's hope in hell to get to any angle, let alone 12 degrees





I then however came across this drawing:



Here the distance between centers of the middlemost mounting points has been adjusted down to 653.5mm.

When I throw these numbers at my calculator, it does present me with an angle as hoped, but the angle is 12.89 degrees (call it 13) as opposed to the 12 stated by the blueprints. As a german myself I am hugely frustrated with my fellow teutons in creating so much confusion.

Anybody here that can shed light on what the correct dimensions should be?

[962porsche]

if you have a concern if the mounting points are at the 12 or rounded up to 13 degrees it doesn't matter . your still in the spec range remember they give an average and then you get the + or - from that .
with the angle i think they give you a plus minus of 2 . so your right in spec weld it !

[Willem Fick]

I actually missed seeing the +-2 next to the 12 degrees indicated, so then 13 makes perfect sense!! Thanks for pointing it out!

Do you then also agree that the center-to-center distance of 653.5 is the correct one, as opposed to 656?

[962porsche]

as long as your in spec of the number with the plus and minus your good to go .
i don't know were or whos spec sheets your have but i'm sure they are good spec's i would have to check them to the ones i have to be sure . but my guess is they are fine .
the two upper ones look the same as what we use the lower one i would not go with i have no idea where it's from ?? so i would disregard it .

with most things you will have a 5MM range and still be with in spec .
with some spec sheets you will have a measurement from on top of the datum line and or under the datum line when you start looking at different spec sheets it may be confusing because one maybe from the top of the datum and the other could be from under the datum .
also some spec sheets may take a measurement fro the edge of a hole and others from the center of a hole . so just go with one spec sheet and you will be good to go .