Chassis alignment help needed

[Mighty Quinn]

I bought a 69 targa with tons of rust and rot.

The car came with new floors and rockers for me to install

I’m wanting to weld in some braces to the car with some square tube for support before I cut away the first rocker.

My problem is that I can see the car has slumped in the guts a few mm.

I want to adjust and shim the front and back half’s of the car so they are true and in lead with each other but not sure what to use as final measurements, elevations or angles.

I have the targa top in place to hold the top of the windshield where it needs to be but there’s still a bit of binding when installing so I’m guessing that’s the car slumping and pinching the roof a bit.

The door gaps on the back edges look good and even, the gaps where the door and front fender meet are not even close but my fenders are garbage and not even fitted, nor worth fitting just yet.

Is there a crazy magic number like 23.65 mm from windshield to targa bar that I use as a reference or is there a simple way to adjust the car?

What’s the best way to adjust the fatigue of the car for rocker re-re?

I know some will say take it to a jig for fitting but that’s not in the budget and that’s not as gratifying as doing it myself.

Any thoughts or help would be great

Thanks

[HarryD]

If you can find someone with a Cellette bench and the Porsche afixtures, you will have all the points in the correct place.

Alternatively, if I am not mistaken, the factory manuals provide the critical dimensions. You need to find the page that gives you the dimensions shown by the letters in this diagram.

[Mighty Quinn]

Great lead, thanks Harry.

The bench and fixtures are a no-go. Would love to make use of one though. I think I saw the fixtures retailing for 6000 , ouch

[HarryD]

You may be able to rent time on a Celette.

[Speed metal]

I turned a former Targa turned cab back to a Targa. Search for Bug Bug! Lots of awesome pelicans provided measurements and photos of em so I could get it done. Including a ton of targa windshield to bar etc measurements.

[dannobee]

Check your local body shops that have a frame rack. The spec book will have drawings/pictures of the dimensions they'll use to pull it back after a collision. Copy or take pictures of the pages you need.