Old school driveline alignment?

[Otee453]

H friends,
This isn’t a question how to set driveline angles per se’, but I’ve been rechecking my angles and a thought occurred to me....

Before we had these fancy little $35 digital angle finders, how did the old school hot rod builders determine their angles?

Its easy to assume the protractor with a weighted swing arm has existed for longer than the digital tool, yet I’ve never seen a vintage version of one. I’m guessing people just used simple trigonometry to roughly calculate angles but when dealing with tenths of a degree, it seems physical measurements would be wildly insufficient, not to mention, how do you get the angle of the pinion with a tape measure?? Bubble level?

[rich grsc]

Eyeballs, common sense and a test drive or two. Everyone just overthinks and overanalyze's everything on these cars. I have built three and helped friends on several more, never have used a digital angle finder. These aren't rocket ships headed to Mars.
Sorta like saying, there is noway they could design and machine engines before CNC machines and computers.

[Otee453]

Eyeballs, common sense and a test drive or two. Everyone just overthinks and overanalyze's everything on these cars. I have built three and helped friends on several more, never have used a digital angle finder. These aren't rocket ships headed to Mars.
Sorta like saying, there is noway they could design and machine engines before CNC machines and computers.

That’s funny. Funny because I can relate. I’m not a machinist by trade but I’ve had my own, well equipped machine shop for years. I build & sell driveshafts for John Deere garden tractor attachments as well as small machine work from gunsmithing other small work. While building this car I catch myself measuring things out to 10 thousands (.010) or less and remind myself that it’s not the damn space shuttle.

[CraigS]

The first time I converted 4 link to 3 link I did it in stages so I could keep driving the car. The last step was to install the 3rd link. I had the panhard and lower links in as well as the banana bracket but the 4 link uppers were still there too. So I measured the clearance from the back edge of the banana to the diagonal panhard bracket tube at about 3/8 inch. W/ the 3rd link installed I adjusted it for that same 3/8 clearance. Drove the car like that for nearly a year but kept seeing threads about the angles here. Finally decided I should measure the angles. Think I rotated that link about 3/4 of a turn. Car drove the same was before and after.
The biggest challenge for me is being sure which way the 2* is. My diff at +2* or -2*? Such a small number and usually looking at it from a weird angle laying on my back I constantly check that by making the angle a visible 20* or so to see if the sign in front of the display stays the same or not. My first go through I had the diff pointing up. Ooooops.