Front end alignment tool.

[Glen]

I have a question for you front end alignment experts. 

I have a tool my father bought from JC Whitney back in the early 70s.  It is two plates separated by rollers.  You drive over it with one wheel and it indicates the toe in. 

My problem is that he instructions were printed on the top and they are no longer readable.  So I am not really sure what the indicator is telling me. 

What I believe is that the tool checks that the toe-in is correct for the camber.  If the top plate moves the toe in is wrong.  If it stays in place it is correct. 

But one friend believes the indicator indicates the actual toe in. 

I tested it on my 2012 Colorado with 8200 miles on it and the indicator barely moved which supports my theory. 

So what do the experts say? 

[TJ Hopland]

Seems like too many dynamic variables to have something like that be accurate.    I remember going to a national chain 'fast service'  place back in the early 90's that had some sort of electronic digital plate thing they drove the car over on the way into the shop that was supposed to be an alignment check.  I remember them telling me my car needed an alignment based on those readings.  I would have had em do it if I had the money.  My alignment could not have been too bad since I think I got over 80K out of the tires.

Are the plates perhaps for use with other tools?   You use plates similar to what you are describing as part of the process to check caster except it would be marked at degrees, something like 46* if memory serves. 

[Dave Shepherd]

Toe plates from back in the day, accurate enough then but there are better ways today to check toe, it was convenient to just drive over for a reading, make sure the mechanisms are nice and free if you are using this, but to really set your own toe, check online for other techniques.

[Jay Friedman]

Every couple of years I just take my '49 to a local tire and wheel alignment shop where they have modern equipment.  They knew exactly how to do the toe-in but I had to show them how to adjust the camber and caster on the suspension (apparently it's done differently on modern cars).  They raise the car on a lift, attach various gizmos under and to the sides of the tires, and do a great job for $49.

[Ken Perry]

what you have is only part of the set up. There is a part that goes on eather the spindal or the rim ,that gives the reading. My friend has a set up like that. He did a good alignment on one of my 60 coupes,worked great. Seems like what you have are called turn plates? Ken Perry   

[Glen]

No the top plate only moves from side to side it is not a turn plate. 

I also have the device that goes on the hub and shows the camber (as long as the car is on a level spot).  It has a bubble level in it and reads out in degrees.  When you turn the wheel you can calculate the caster from the readings. 

I may also have the spring loaded rod that goes near the tread between the front wheels to measure the toe in.  I guess I need to find that tool. 

Back in the day I could do a good alignment on my 61 Coupe DeVille with these tools.  The final check was to run the car over this plate.  The problem is I don’t remember if the indicator was supposed to show the toe in or if it shows the toe in error. 

[TJ Hopland]

Probably at least 75% of the cars built in the last 25 or so years toe is the only thing that is adjustable from the factory.   Most of those you can buy special eccentric bolts that will let you adjust camber.   In most cases to adjust caster the whole ' K member' (engine and trans) has to be shifted which most shops don't want to touch.   If you read the fine print when you get a '4 wheel' alignment there is usually something in there about 'we only adjust factory adjustable stuff back to spec' so in many cases they adjust toe on the front, take your $50-100 and thats that.   Certain lower and mid models have adjustments and the higher end stuff seems to always have adjustments.   

You want to be amazed at an overcomplicated mess look at the rear suspension of your average low to mid priced small car.   Daughter had a 2000 ish Focus and that had wicked rear bump steer and clunked.   Got to looking at the rear suspension and there had to be at least a dozen links and pivots on each side.   Just a little slop in each joint pretty much ruined the car.   Would have cost something like $900 to replace everything on that one side.   A shop told me that those cars the rear is actually out of alignment by design which is why they tear up tires.  Apparently if they are aligned to what would be typical / logical they don't handle worth a darn so the fix is a little miss alignment to make them handle better at the cost of extra tire wear.

I think the K member thing is part of the euro/ 'world car' design.   On older American cars with struts there was usually a method to pivot the top strut mount plates to set caster.  Does not seem like it would be that hard to still include that in the design but apparently they feel that not having it adjustable makes it not need adjustment as often.   I know in my business the machines used to have several adjustments that really should not have needed regular adjustment and they always seemed to need adjusting.  At some point they changed the design slightly and got rid of the adjustment mechanism (likely cost savings) and I hardly ever had to adjust them after that so I could maybe see some truth in them not designing them with the ability to be aligned.