For those of us who are curious, and don't know just exactly what it is you're talking about, could you post a few pictures? It might also be that there are other tools that work in a similar way, and we could help with instructions for those.
Damn near blew it on that one, It is a turning radius gauge that you compare the reading on one front wheel to the other front wheel, It's on the right hand side on this image. This is out of the GM Hertitage center archives vehicle information kit for my 48 pickup with stock axle. Normally most of us who have the plates Will turn one wheel to a set point and go around and read the gauge on the other plate. My plates only go to 20 and are more what racers use than what you will find in a front end shop. They don't have the lock down pins that most plates have and don't have a pointer on the plate. the gauge only goes to 20 because the guys using them usually just turn the wheel out 20 degrees, level the caster gauge and then turn the wheel in to 20 degrees and read the caster. Where you would and maybe will really used that part of the gauge for it's intended purpose is if you are checking to see if one steering arm might be tweaked a bit and not turning that wheel to match the other wheel. When one wheel isn't wanting to track smoothly with the other wheel. That set of home made (won't pass inspection ) steering arms that are on my round back spindles are a great example of the reason you should check the turning angle.
I can't see exactly how that one works but with regular gauges this is how you read caster. Let's say we're working with the drivers side, you first turn the tire to the left (forward) to 20° and take a reading, let's say it 1° negative then we turn the tire the other direction to 20° and take another reading, let's say 1° positive so we add them together which gives us 2° positive, lots of math evolved. Other style, again turn forward 20°, center bubble, turn back to 20° and take a reading this is your total caster for that wheel, repeat for other side. If the front suspension is totally adjustable run about 3/8° more caster in right wheel, helps make up for road crown. I do this day in and day out, several times a day......
For someone who aligned front ends as long as I did and did work using a few different machines that can be a bit confusing. The big confusing part is that that dial gauge is the swiss army knife of front end equipment meaning that it has a number of functions for different steps in the alignment process and most of us were thinking of one step in our comment. Down the list and I may miss a couple: you use it to measure how far you turn the wheel in and out while checking caster. You use it to check the turn angle from one wheel to the other. You don't actually use the gauge to center the steering wheel but the instructions are real close to what I did on hundreds if not thousands of front ends. Center the wheel and lock it down if possible, sight down the side of the tire to the back tire and see which one is lined up great with the rear tire and which one is off angle and adjust your toe in on the off angle side. (this only works on independent with two shorter tie rods). I've never seen it written out on a gauge in the past 60 years though.
I've worked with and played with numerous camber/caster gauges but none like that one. Would love to get my hands on one of those and compare it to the ones I use every day at work and see how accurate it is to mine. I've compared some and the best I can say is they were kinda close. ...
https://patents.google.com/patent/US2474616 but the OCR didn't do a very good job of reading the patent and turning it into text.
That would be a first for me. I have never seen one like that before. I;m used to Snap On and Bear equipment for the most part.
If you search "Kwik Ezee" there is an older thread regarding the camber/caster gauge. They turn up on Ebay often enough for about $100. I got carried away and have six of them from various generations in my alignment tools collection. I'd love to reconnect with the person behind this company. I called him back in 2011. It would be nice to save the website for historic reasons.
Never used this style BUT I would bet this is how it works.. CAMBER- you find a totally plump rail or totally flat vertical surface. We actually had a wheel mounted to the wall that was leveled and squared with a machinist level. So from this point on I will reference the calibrated wheel. You mount the gauge to the calibrated wheel, turn the silver ring to center the bubble, once the bubble is centered THEN the silver outer ring is turned WITHOUT turning the part its mounted to. you turn the silver ring to "0", the ring probably has some kind of locking device, be it a screw etc that has to be loosened to allow it to slip on the collar. Once at zero you can now take it to the vehicle and get a true camber reading.. CASTER - now this I would bet I'm 100% correct. With the gauge on the wheel, you turn the tire 20° to the left if working on the right side of car or to the right if working on the left side the car, on caster you always read front to back. Once your at 20° you center the bubble with the brass ring, once bubble is centered you loosen that big thumb screw and rotate just that ring itself to 0 on that ring, tighten down thumb screw, now turn tire 20° to the back and rotate the entire brass collar assembly until bubble is centered, take the reading off of the brass collar and there is your caster reading... I would bet that there may be a thumb screw for the silver collar too. If you decide to sell it I'd be interested in it !! ...
Old thread and a real old guage but in reality it works very simply. It attaches to the hub and you turn the camber dial to center the bubble on the level on the line and read the camber. Turn the wheel the designated degrees forward or back and Zero the caster guage and turn it the other way to the designated degrees and read the caster. In truth you can probably use it to see if the fancy high dollar computer equipment is reading right. It should do the job if the guy using it knows what he is doing.
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