Motorsport Wheel Alignment: Slip Plates & Turn Plates
Slip Plates & Turn Plates
02.20
00:00 | - One of the common tasks we'll be performing while making adjustments to the suspension is to jack the car up in order to reach the various components that we need to access and adjust. |
00:09 | This might seem like an obvious detail but the part that's easy to overlook is that when we lower the car back to the ground, the tyres and suspension will not settle back to the same position they were in before we jacked the car up. |
00:21 | This is due primarily to the fact that the wheels tend to move inwards towards the chassis centreline at full droop, which is what will happen when the car is jacked up off the ground. |
00:31 | Now when we lower the car back onto the ground, the tyres will contact the ground and they tend to bind up because they can't easily move outwards to the position they'd be at in a normal ride height. |
00:41 | This means that the car will sit higher than it should and of course all of our alignment readings will be affected. |
00:48 | One option to correct this is to simply roll the car back and forth a few metres which will let the tyres settle into their natural position. |
00:55 | However after going through the trouble of setting up our string alignment equipment, that's not always a two minute job. |
01:01 | A better and faster option is to use slip plates under the wheels while performing our alignment. |
01:07 | These come in a variety of styles however in simple terms, they consist of two metal plates with the PTFE coating which can easily slide or move relative to each other. |
01:17 | We place these under the tyres and then when we lower the car, the slip plates slide on each other, allowing the tyres to move into their natural location with minimal friction. |
01:27 | Depending on the design, commercial slip plates can be quite expensive, however you can make your own with a couple of thin, stainless plates with a liberal coating of grease in between. |
01:38 | Turn plates are a little more complex and are used for accurately measuring how much the steering has been turned. |
01:44 | These are used in conjunction with a caster, camber gauge that we just discussed, in order to measure caster angle. |
01:50 | This normally involves setting your caster gauge, rotating the steering 20 degrees in one direction, zeroing the gauge and then turning the steering back the opposite direction before reading the caster. |
02:01 | We haven't found any truely cheap turn plates that are suitable for the DIY enthusiast however some of the camber, caster gauges are machined with 20 degree angles on their extremities, which with the aid of your string lines, can do a pretty good job if you don't have turn plates. |