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Motorsport Wheel Alignment: Parallax Error

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Parallax Error

02.21

00:00 - When we're performing string wheel alignments, understandably we're going to be taking plenty of measurements using a ruler, referencing our strings and it should go without saying that if we want any chance of our alignment being where we need it to be, the accuracy of these measurements is critical.
00:17 Now this isn't a particularly difficult task to complete, however there is one aspect we do need to be aware of, this is the term parallax error, and this can drastically affect the accuracy of our measurement results.
00:30 Now parallax error comes in when the ruler that we're using to take our measurements is located a distance away from the string that we're using as our reference.
00:40 When this is the case, depending on the angle we view the string in relation to the ruler, this is going to give us an error in the measurement that we're looking at.
00:49 As we can see here, as we alter that angle at which we're viewing the ruler and the string, we can see the apparent measurement changes.
00:57 To eliminate this, we want to first of all make sure that our ruler is located very very close to the string that we're using as our reference.
01:05 Ideally we want this to be no more than a few millimetres away from the string and this reduces any chance of parallax error coming into play.
01:13 At the same time though, we can also end up getting this effect by angling the off the rim surface.
01:20 We always want to make sure that the ruler is parallel to the ground or at least as close as we can get it to parallel to the ground.
01:27 Once we've got these two aspects out of the way, the last aspect is to make sure that when we are making any readings, we are viewing from directly vertically above our string line.
01:37 Now if we take these simple precautions it's going to give us the best chance of getting accurate readings and avoid the chance of parallax error.
01:44 One last aspect that's not strictly related to parallax error but is worth covering in this module, is the way we align our ruler markings with the string.
01:53 In order to get accurate readings we want to make sure that our ruler is perpendicular to the string and we can use the marks on either side of the ruler to make sure that this is the case.
02:05 Now if we don't do this, it's very easy to have the ruler coming off the rim at an angle and this again can affect the accuracy of our measurements.