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Practical Corner Weighting: Setting up a Flat Patch

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Setting up a Flat Patch


00:00 - Before we can perform our corner weighting, one of the first and most important steps is to choose a suitable location where you're going to perform your setup.
00:08 This is called our flat patch.
00:10 As we discussed in the body of the course, you're going to quite often find that most seemingly level surfaces, when we actually start digging down and checking, aren't actually as level as you thought.
00:21 And this will have an impact on the accuracy and repeatability of our corner weighting measurements.
00:27 The first step therefore is to choose a suitable piece of ground where we're going to be performing our setup, be that in your home workshop or at the track.
00:36 Ideally what we want to do here is choose some flat concrete ground, like the workshop floor that we've got here.
00:43 We don't want to be making our setup on dirt, gravel or for that matter asphalt as we can have problems with the scales not sitting flat on that particular surface.
00:54 Even with our concrete floor in our workshop here there are still some aspects we need to take into account.
01:01 Here you can see we've got some expansion joints that have been cut into the concrete slab and we want to make sure that when we're choosing a suitable location for the car to sit during the setup process that we don't position the car in such a way that we're going to end up with the scales spanning across those expansion joints.
01:19 If we've got the scales spanning across the expansion joints, it's quite likely we're going to have an imbalance and we can end up in a situation where the scales won't sit flat and will actually rock from side to side across those joints.
01:33 Once we've chosen a suitable location, getting away from those expansion joints we can then mark out the location of each corner of the car and this is going to be important for the next step of our process.
01:43 And marking out each corner of the car can be done simply with a product such as masking tape as we've used here or alternatively race tape, it really doesn't matter but it's ideal if we've got something that's going to be easy to remove off the floor once we've performed our setup.
01:58 Once we've got our patch marked out we can then roll the car out of the way so we're going to have free access to each corner that the car's going to sit on for the next step of our process which is checking to see how level our floor is.
02:11 Before we carry on, it's a good idea to use a broom and just sweep any debris off the area that we're going to be setting the car up on.
02:19 Any small stones or debris can affect the accuracy of our results when we go and put our scales down on the floor.
02:26 In order to do this, we're going to use two sockets, and it's really important with these sockets to make sure that they're exactly the same height.
02:35 We're going to use those two sockets to support a long section of rectangular aluminium extrusion.
02:42 That's going to straddle those sockets and we're going to place the sockets on each corner of the car.
02:47 We're then going to use our digital camber guage in order to check our aluminium extrusion for level.
02:52 Starting at the back of the car, we're going to place our sockets on the two rear tyre patches approximately in the centre, we don't need to get too fussy here, and then we can lay our aluminium extrusion on top of those two sockets.
03:06 Choosing a location approximately in the middle of the two sockets we're then going to place our digital camber gauge down on top of the aluminium extrusion.
03:15 Now that we know that our floor is flat across our rear axle line, we're going to repeat that process across the front axle line.
03:22 The process we go through there is exactly the same and again we can see we're we're fortunate that our floor is still level across the front axle line.
03:30 Finally we're going to measure across the left hand side of the car between the front and rear tyre contact patches.
03:37 Our camber gauge is still showing that our floor is flat so we're very lucky in this instance.
03:44 Now that we've measured three planes there, we've measured our rear axle line, our front axle line and our left front to rear, we don't actually need to measure on the right hand side.
03:54 If all three of the measurements we've taken so far are showing zero degrees, this means by default that the right hand side will also be zero degrees between the front and the back.
04:05 Now you're not always going to be as lucky as we are here so we'll show you how we can make some adjustments if we find that our floor isn't flat.
04:13 In order to set this up, we've purposefully used a socket with a different height across the left hand side of our car.
04:19 And when we lay our digital camber gauge down on top of the aluminium extrusion, this time we can see that it's showing a 0.3° error.
04:29 Now you can also take note of the little arrows on the camber gauge and this will give you a hint as to what changes are needed.
04:36 In this case we can see that at the rear of the camber gauge the arrow is pointing down and at the front it's pointing up.
04:43 What this means is that we can fix this out of level situation either by lowering the rear, obviously that's not possible with our concrete floor, or alternatively we can raise the front and that's exactly what we're going to do.
04:55 When you're considering your options for raising one corner of the car like this, it's important that we choose a product that's going to be nice and stiff or incompressible so it's not going to result in any error creeping in with our measurements.
05:11 There's a variety of options but I choose to use a 300 x 300 vinyl flooring tile.
05:17 These are around about 1.1 to 1.2 mm thick but the more important aspect is that they aren't compressible when they're on the floor.
05:26 And what we can do is stack as many as we need in order to correct that out of level.
05:32 In this case we'll place two of our vinyl flooring tiles on the front left corner of the car and by refitting our socket and checking again with our camber gauge, we can see that that's got us to a situation where it's reading level with zero degrees.
05:46 We're then simply going to repeat this process, shimming any of the corners that are low until everything's measuring perfectly level.
05:53 This can be an iterative process so it's a good idea once you've made any adjustments with your vinyl tiles to do a final recheck and make sure that everything is still measuring level.
06:05 If you are also setting up a flat patch in your home workshop where you're going to be repeating this process consistently, it's always a good idea to take note of exactly where the car's sitting as well as how many tiles you need to correct and level the scales, this way it's going to make the process much faster when you repeat it in the future.
06:25 Once we've got our flat patch levelled we can then place our scales down on the floor.
06:30 One final check though is to always make sure that the underside of the scales are clean and free of any debris.