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Motorsport Wheel Alignment: Checking Suspension Bush Condition

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Checking Suspension Bush Condition

07.47

00:00 - One of the suspension components that's really easy for us to overlook when we are dealing with our wheel alignment is the condition of the suspension bushes.
00:08 This is important because as the suspension bushes age and wear, they allow excess play and this makes it more and more difficult for our alignment to stay as we've set it statically in the workshop.
00:20 In extreme situations where the bushes are very worn, this actually can be quite dangerous, allowing excessive movement of the wheel alignment and this can make it very difficult for the driver to control the car.
00:32 At best, it's going to make it difficult for us to extract the maximum performance out of the car on the racetrack and of course at worst, it could end up in a serious accident.
00:42 So we do need to be quite particular when checking the condition of these bushes.
00:46 In general, when it comes to the types of bushing that we'll be dealing with in our cars, we've got two styles to choose from.
00:53 We'll probably be either using a factory style rubber or urethane bush or alternatively if we're getting a little more serious, these may be swapped out in exchange for spherical bearings.
01:04 Spherical bearings, as we've already talked about in the body of the course, are the superior choice because they remove any of the compliance from the factory rubber or urethane bushes, allowing much more accurate control of our alignment, however on the downside, these do tend to wear out more quickly so they do require more maintenance and more frequent checking.
01:24 When it comes to checking the condition of the bushes, there's two ways we can go about this.
01:29 To start with, if we have all of the suspension components out of the car, we can go and perform a visual inspection of all of the bush material, making sure that they are intact and are in good condition.
01:39 Due to the fact that with the suspension arms out of the car, it's really difficult for us to apply significant amount of force to the bushes, it actually can be a little hard for us to really prove that those bushes are in good condition but it's still a good idea before we go to the trouble of installing our suspension arms, to just visually inspect and make sure that they appear to be in good condition.
02:01 If we're dealing with a urethane or rubber bush, in particular what we're looking for is any signs of the rubber or urethane material perishing or cracking between the inner component of the suspension bush and the arm that the bush is installed into.
02:16 If there's any sign of this cracking, it means that the suspension bush should be replaced.
02:20 In extreme circumstances, if the bush has really been allowed to deteriorate, we may even find that the inner component of the bush is essentially completely free of the exterior component, allowing excessive movement.
02:33 Clearly this is no good and we'd be needing to replace that style of bush immediately.
02:38 When we're dealing with spherical bearings or rod ends, it's actually a little bit more difficult for us to check their physical condition out of the car unless they're very badly worn.
02:47 What we still want to do though is hold the inner component of the spherical bearing and what we want to do is apply some force onto the suspension arm.
02:54 We're trying to feel if there's any noticeable free play between the inner and the outer component of the bearing.
03:02 Now all of the checks we've just talked about are the sort of checks that we'd be performing before installing either new or second hand suspension components into our car.
03:11 However once we've got our car set up and aligned, we're more likely to be performing these sorts of checks with the components already in the car.
03:19 It might sound difficult but in some ways it actually makes our job easier and there are a few simple checks that we can go through here to confirm that there is no free play in our bushes.
03:30 What we want to do is start with our car either up on jack stands or preferably on a hoist and we want to start at one corner of the car.
03:37 We're going to grab the top and the bottom of the wheel and we're going to apply some force, trying to rock the wheel inwards and outwards on the car.
03:46 And what we're going to be doing here is feeling for any free play.
03:49 This might sound a little bit tricky but when there is some wear in the suspension components, we'll feel a noticeable clicking and that's our sign that something isn't right here.
04:00 Now once we've checked in the vertical plane, we also want to do exactly the same horizontally across the wheel.
04:07 Now the reason we're doing this is it will highlight different suspension bushes or components.
04:12 When we're checking vertically, we'll be checking the bushes in the top and bottom arms or the top hat in a MacPherson strut style suspension.
04:20 When we do this horizontally, we're going to be checking if there's any play in, for example our tie rod ends for our steering.
04:27 Now I should mention here that this can be a little bit misleading because if we have any wear or play in our wheel bearings, this test will also highlight that.
04:37 So if we find that there is a little bit of free play there, we're obviously going to need to dig in and investigate further to find out the actual source of that free play so that we can fix or replace the correct components.
04:49 When we're doing this, it is important to apply a significant amount of force and rock the wheel backwards and forwards quite aggressively.
04:57 It's not enough to just give the wheel a gentle nudge because we're trying to replicate as much as we can, the sort of forces that are likely to go into the suspension components when we're out on the racetrack.
05:07 Once we've performed our initial inspection, we should have a pretty good idea of any problem areas, which is going to highlight where we're going to need to inspect a little bit more thoroughly.
05:17 Now it's time to get the car up on the hoist so we can perform that more thorough inspection.
05:22 And unfortunately this is where it does get a little bit more difficult if you are restricted to performing your checks on jack stands, but it's not impossible, you're just going to need to spend some time lying under the car on your back.
05:34 It's also useful during this inspection to have a helper.
05:37 And what we can do is inspect the suspension components while the helper is either rocking the wheel or moving the steering wheel and this can help us highlight exactly where the free play or movement is coming from, highlighting which suspension bush or component may need to be replaced.
05:53 The next step of the inspection process relies on using a long pry bar and what we're going to be doing is going through each of the suspension bushes on the car, we're going to get our pry bar between the suspension component and a solid part of the chassis and we're going to apply some force on that pry bar, making the bearing or bushing flex.
06:12 When we're using this process to check our suspension bushes, it is a little bit easier to pick up any wear in the bushes when we're dealing with rubber or urethane bushes because of course spherical bearings, even when they are quite badly worn, are only going to move very slightly.
06:27 If we're careful though, we're still able to go through and check each of the particular bushes or spherical bearings and make sure that there is no excessive free play.
06:36 Once we've moved through the car from from to back and we've checked all of the suspension bushes or spherical bearings on the car, we should have a thorough understanding of where any problems lie and if so, which particular components need to be replaced.
06:50 Now this is a set of checks that we should be doing relatively regularly, particularly if your car is seeing regular track use, as these suspension components will wear quickly.
07:00 Particularly with the likes of a factory rubber or urethane style bushing, these do tend to wear slowly so you're not necessarily going to notice an immediate loss of performance but over time the car will start handling worse and worse.
07:15 You may be surprised to see just how much performance and accuracy you pick up by replacing worn suspension bushes.
07:22 When it comes to spherical bearings, one of the key signs when we're actually out on the racetrack that a bush may need replacing is that it will start rattling.