Practical Automotive Maintenance: Materials

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Materials

04.54

00:00	The material we use for our bushings entirely depends on the vehicle's intended use, as each has its own set of pros and cons that need to be carefully considered.
00:09	There are three commonly used materials when it comes to bushings and mounts.
00:13	Rubber, polyurethane and solid.
00:15	Let's start by discussing the most common and forgiving option first, rubber.
00:19	In the vast majority of cases, rubber is the go -to material for OE manufacturers and you'll find it throughout nearly all stock vehicles.
00:27	This is for very good reason.
00:29	It's ideal for everyday road usage and it's also cheap to produce.
00:33	Rubber provides excellent absorption and flexibility, keeping NVH, which remember stands for noise, vibration and harshness, to a minimum.
00:42	These bushings can come in a few variations, either being entirely made from rubber or as a composite where rubber is bonded to metal sleeves for specific mounting requirements.
00:52	There's no free lunch though and rubber's upsides also contribute to its downsides.
00:56	While it provides excellent ride quality and minimal NVH, it begins to fall short in high -performance motorsport and off-road environments.
01:05	Due to its compliance, we tend to see reduced handling precision as the car's static alignment settings for camber and toe can and will move around significantly as rubber bushings flex, especially under the high loads seen with aggressive cornering, braking and acceleration.
01:21	This means the material can excessively flex or stretch, causing fatigue and reducing its lifespan.
01:27	On top of this, rubber's also susceptible to harsh elements and operating conditions common in more extreme driving scenarios, further decreasing its durability.
01:37	All of this can lead to cracks or tears in our rubber bushings and that can compromise suspension geometry, leading to poor tyre contact, vague steering feel, reduced traction and compromised handling.
01:48	This is where rubber should be substituted for the superior materials that we use in motorsport, like polyurethane or a solid material.
01:55	Polyurethane is the most common aftermarket bushing material.
01:59	It offers greater durability and stiffness than rubber, drastically reducing vagueness and making for a more precise and predictable vehicle.
02:06	This all comes at a price though, because while polyurethane does sharpen up our vehicle's handling behaviour, that sharpness also means an increase in noise and vibration, making for a less pleasant car to drive on the street.
02:18	There are dozens of manufacturers out there producing these products, with some of the most popular being SuperPro, Whiteline, Energy Suspension and Powerflex.
02:27	They're all similar, but it's worth doing a little digging to figure out which is going to best suit our application.
02:33	The final step past polyurethane is a solid material, usually aluminium, delrin or spherical bearings in the case of suspension strut tops and aftermarket arms.
02:43	As the name suggests, these bushings are completely solid, meaning there's almost zero flex or compliance, making for an incredibly harsh ride that transmits nearly all the vibration and noise back into the chassis.
02:56	It might be tempting to just shrug your shoulders at this point and say, so it's less comfortable, no big deal, but the reality of living with a car that uses these type of solid bushing on the street is pretty unpleasant.
03:08	It's harsh, noisy and will make you second guess every creak, knock and whine, wondering if something's broken.
03:14	The upside here is that this means there's almost zero deflection or compliance, providing the ultimate feedback and sharpness with zero slop in between the components and the chassis or the driver controls.
03:26	Many of the manufacturers like Whiteline or Hard Race producing polyurethane bushings also offer solid options, with plenty of specialists like Technotoy Tuning selling options for more niche vehicles.
03:38	It's worth mentioning that some modern vehicles have started transitioning into the use of hybrid bushings and mounts designed to offer variable levels of compliance through dual compounds at the simplest level or through hydraulics and electrical control as the tech gets more advanced.
03:53	These are very impressive in providing the best of both worlds depending on the driver's needs, but at the time of filming they're also very expensive, complex, usually limited to OEMs and generally, not serviceable.
04:06	Let's sum up what we've covered in this module before moving on.
04:09	The choice of bushing material depends entirely on the vehicle's intended use, as each option, rubber, polyurethane and solid, offers unique advantages and trade-offs.
04:20	Rubber is the most common in OEM applications due to its comfort and low NVH, but it lacks precision and durability in high performance conditions.
04:29	Polyurethane improves stiffness and handling feedback for motorsport and spirited driving, though it increases noise, vibration and harshness.
04:37	Solid bushings provide the ultimate precision and zero deflection at the expense of terrible NVH, while hybrid mounts in the high-end vehicles aim to find a balance of comfort and performance, but remain costly and complex.