Locating the Horizontal Zero Plane

[Joscarlang]

Does anyone have any input on the exact location of the horizontal zero plane from the trunk and other locations? I'd really like to laser the car and extend my sharpie lines so I can rely on the measurements on the factory drawings more.

The Factory prints I have are pretty blurry when I zoom in. I think the line is just on top on the hump for the steering rack but not sure.

I have the car jigged and leveled. The photos show where I think it is.

[Joscarlang]

To clarify what I am asking:

As you can see from the factory prints there are multiple "Plan 0" points I have highlighted.

I'm looking for the horizontal "Plan 0" line as it exits the steering rack area and runs forward through the trunk. (I can also transfer this to the exterior of the car and use it to aid in install of my outer rockers/bumpers etc.

Once I can establish this line, (Image #1) I can shoot a laser from the front of the trunk and measure down to the front suspension pan bolt points in order to ensure that the front of the pan is at the proper elevation relative to plan (everything else). Then using a tram gauge check other locations to square.

The entire front of the car was poorly replaced without jigs or proper measurements 30 years ago and then rusted out again. There isn't much I can rely on to measure from. Not to mention the car was in minor front end collision that may have shifted things too. With that being said, Knowing the location of Plan lines is crucial to getting thing back to where they belong.

I know this probably belongs in the bodywork forum but this on gets far more traffic!

[Jonny042]

You are on the right track - I ended up figuring out a datum line in the door jamb - the jambs and sills run horizontal, which you can take as gospel, so make sure you've got those horizontal and it will all fall into place.

Check out page two of my build thread it may help. I also have a pdf document that might have better resolution for some of the drawings, so PM me your email address and I'll send it along.

Laser level stuff here: Project Heavy Metal - an all steel classic, remastered

[Jonny042]

My datum line:

[RSTarga]

Get thee to a Celette Jig.

[Jonny042]

There's more than one way to get to the proper end result. A Celette jig would be nice, but it looks to me the OP is on the right track.

There's only one perfect. How you get there doesn't matter.

[Joscarlang]

Originally Posted by Jonny042

You are on the right track - I ended up figuring out a datum line in the door jamb - the jambs and sills run horizontal, which you can take as gospel, so make sure you've got those horizontal and it will all fall into place.

Check out page two of my build thread it may help. I also have a pdf document that might have better resolution for some of the drawings, so PM me your email address and I'll send it along.

Laser level stuff here: Project Heavy Metal - an all steel classic, remastered

Thanks Jon!
Got your email.

RStarga: I've had the car on on a celette jig after the collision happened. So i know things are generally where they belong. I'm just trying to get it next to perfect and put back together. Then I'll take it back to the frame shop to confirm.
Not everyone with German sports car has groß Deutsche marks in the the bank!

Being a Welder fabricator by trade, I read and build things from plans every day.
I'm confident that I will get it very close if not perfect without a cellette.
But yes, that would be the the shortest most accurate route.

[boyt911sc]

Joe,

From one of your attached pictures (second to the last), shows the location of the Zero Plane from the bumper mount area and hood. From the rear, it is 42 mm from the center of the torsion bar tube. You could find this data from the PSM (Porsche Shop Manual) volume VI, section 8 (body), page 18.1-1/1.

Tony