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When data let's shops down....


Tony
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Here is an example of a Ford data set. Now where it's wrong is when the tolerance is nearly three times the value of the actual target data setting.

Some company's might measure and read the cars chassis positions and say "it's" all green so there's no problem, but if each angle is at different points within the data-set then there really is a problem..... Despite it being green.

wim says. Green does not mean it's right.

IMG_1212.JPG.5b41bbcf8151131857077e06e4ec0566.JPG

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I think it's a build issue. Mazda with the MX5 Mk3 NC did the same thing for a different reason. Allowing such a wide tolerance makes for an easy build but it also opens the door to "aligners" understanding what the actual issue is. For example i could set all the chassis positions and use the cross tolerance's and it would appear on measuring everything is fine but the car will drive sideways.

This where understanding the geometry and colour on the screen is divided. When i train people i turn off the colour, so they have to consume the numbers and meaning's the numbers represent. 

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4 hours ago, Tony said:

This where understanding the geometry and colour on the screen is divided. When i train people i turn off the colour, so they have to consume the numbers and meaning's the numbers represent. 

Best way to do it really. So much software has made it far too easy for people to use, which is a good thing. But when problems arise they don't have the know-how to find a solution.

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The understanding is to be aware of the geometric forces involved with each angle. Then understand the same forces apply to every car ever made. Then understand the collection of forces on that particular car.

Example. From the data above let's assume the OSF camber is -1 degree and the NSF castor is 2 degrees 38' and all the other angles are near perfect and everything is and will be in the green. Given the collection of forces between the camber and castor that car would pull violently left.

So moving away from the colour "red, green" says it's right or wrong understanding the difference between numbers and forces, plus dynamic and static opens a different realm in the way the data should be analysed.

Problem with the data displayed above is it's too vast? Normally i find it's due to a sloppy build issue.. Example Fiat's 500 model had a history for rear tyre wear. The problem angle was the toe being out of tolerance, but rather than correct the build they widened the tolerance :o So now any tech reading the geometry numbers would say "it's green"...... Well yes it is now because the data offered by Fiat has widened but the fact remains the toe angle, which has a lateral force is wrong.

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