Has anyone seen one of these?

[Glen]

My father bought this from J. C. Whitney back in the 60s.  Its purpose is to check toe-in on the car.  You put it on the ground in front of the car and drive one tire over it.  The indicator shows the results.   

When it was new the instructions were painted on the top with yellow paint, but when I got it there was not one word that was readable.  So I cleaned the rust off and painted it.  its made with two steel plates with rollers between them.  The indicator is attached to the top plate and it has a pin attached to the bottom plate.  As you drive over it, if the top plate moves the indicator shows how much. 

It was my thought that if the toe in was correct for the camber on the car the plate wont move.
But I just had the front end aligned on my S10 with one of those high tech laser machines.  In the "results" picture you can see the indicator has moved. 

Anybody know the theory behind this thing? 

[The Tassie Devil(le)]

G'day Glen,

No matter how you drive over it, it will always show that there is going to be movement simply because there is an amount of Toe-in set into the alignment specifications.

But, as you said, you need the instructions, which will tell you how much the arrow movement relates to.

Bruce.

[Roger Zimmermann]

I have something similar; it was intended for dealership usage, therefore more stable than yours. Of course, you can only check the toe-in or toe-out with that device.

[harvey b]

I had a small pickup aligned one time at an alignment shop that had a setup like that they drove over it and it measured the movement of the tires side to side?,it was big gizmo that was part of the floor,it was the worst alignment i ever had,it was worse when i picked it up then it was when i dropped it off . I was never so upset at someone for that,i have never been back and that was 10 years ago,they said it was fine,but it was a mess.I wouldnt use that at all,make a wall hanger out of it. Harveyb

[fishnjim]

https://www.amazon.com/Gunson-G4008-Trakrite-Wheel-Alignment/dp/B0012M9KEC
Something similar.
J.C.was not known as high quality stuff, so I'd not be too excited about it.
Nostalgia value.   I think it's suppose to react to the difference in weight applied by the tire from side to side.   Sounds good but not the best measure as the one wheel being measured is higher vs all in the same plane.   
During that time, alignment was a "big" issue, and the suspensions/steering weren't very robust(especially on the lower brands), roads weren't great, lots of manual steer(pulling), and with bias plys would wear tires quickly.  Not so much a Caddy owner issue.   They could afford it.   But the depression era thinking still loomed in people's minds.   In perspective, you could buy an average bias ply for about $30 plus, but that was good money then.   So one was always going in for alignment and the garages made out.   Muffler & exhaust repair were "hot" too.  There were more local and smaller shops.   Most gas stations with a garage that sold tires would have alignment service.   They used just mechanical equipment back then so more labor involved.  You always prayed the ball joints were good, $$$ to fix, before you went in.   
The laser was just being invented and no one could foresee much use for it then, but after 60 years of developments, it's quite common now.

[CadillacFanBob]

Glen,

You may trying to call or e-mail J.C Whitney they are located in LaSalle, Illinois phone 866-529-4359 or e-mail address : jcwhitney.com maybe by chance they may have on file the directions, just a thought.
They also have the original large Warshawsky (the large store was located at Archer and State Street in Chicago) sign outside of J.C Whitney in LaSalle, Il was the mail order store.


Bob