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Motorsport Wheel Alignment: Suspension Arms

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Suspension Arms


00:00 - If you're planning on getting serious with your car, then there's a good chance that you're going to need to consider replacing some of the factory suspension arms in order to get the sort of adjustability you're going to need.
00:10 Providing you're dealing with a popular performance car with known shortcomings in the stock suspension, there's almost certainly going to be a range of manufacturers offering bolt in options.
00:21 There are a couple of considerations here though.
00:23 First and foremost, any time we're making a significant change to such critical parts as the suspension arm, we do need to consider the safety and reliability of that part.
00:34 It should go without saying that dealing with a reputable manufacturer with a proven track record is essential.
00:41 Depending on your local laws, there may also be some difficulties fitting aftermarket suspension arms and remaining road legal so you do need to check with your local authorities before making any purchases.
00:51 We also need to consider the type of suspension bush used in any aftermarket suspension arms.
00:58 While most high quality aftermarket arms will use a rod end or spherical bearing in place of a factory rubber bush to reduce compliance, you may also have options that use a cheaper urethane bush to reduce compliance without introducing too much noise and harshness into the chassis.
01:13 There isn't necessarily a right choice here, as this will come down to what the car will be used for.
01:19 You don't need to worry about these choices right now though as we wil cover suspension bushes in detail in an upcoming module.
01:25 Most aftermarket suspension arms will utilise a left and right hand threaded sleeve that the rod end screws into, which allows you to loosen the locking bolts or nuts and then turn the adjuster to shorten or lengthen the arm, while it's still fitted to the car.
01:40 This is one area that can be easy to overlook when you're buying suspension arms but it can make a huge difference to the convenience of actually making adjustments.
01:50 For example if you're adjusting arms that don't use the left and right hand threaded sleeve, and simply instead use a rod end that threads into a welded boss, you're going to need to remove the arm from the car each time you want to make an adjustment and as you can imagine, this is hugely time consuming.
02:06 Another subtle aspect with this type of adjustment method is that your adjustment may end up being quite coarse since you can only turn the rod end a minimum of a half turn, which may not allow you to get the exact adjustment you want.
02:19 One last point that's important to understand when dealing with aftermarket suspension arms is to make sure you have sufficient thread engaged for the rod end or adjuster in the arm.
02:29 A rule of thumb here is to make sure that you have a minimum of 1.5 times the outside diameter of your thread engaged in the arm.