Bushings are small components, often made of rubber, pressed between parts like suspension and steering components, engine mountings, etc. They look like small rubber circles and are installed to maintain a smooth and noiseless driving experience. Imagine how a car would perform if every component was rigidly bolted to each other. The noise and vibrations would be very harsh, making the driving experience miserable. Fortunately, bushings isolate these noises and ensure a comfortable drive. But are stock bushings worth the investment? Are you looking for new car bushings and overwhelmed by the types of bushings available? Don’t worry, this article will help you with all of that. This article will also help you to understand the difference between rubber and polyurethane bushings and which one is best for you.
In this article:
1. What Is Suspension Bushing and What Does It Do?
2. Polyurethane vs Rubber Bushing: Which Should I Choose?
- Ride Quality
- Lifespan
- Hardness
- Maintenance
- Installation
- Performance
- Squeaking
3. When Should You Use Polyurethane Bushings?
4. How Do I Know If My Bushings Need To Be Replaced?
5. How to Make Polyurethane Bushings?
1 What Is Suspension Bushing and What Does It Do?
Newer vehicles have complex suspension systems with links and joints held together by bushings. These bushings are a type of vibration isolator that is made of rubber or polyurethane. The purpose of these bushings is to avoid metal-to-metal contact while still allowing the suspension system to move freely. Made from shock-absorbent material, they are crucial in ensuring a smooth ride.
Bushings are basically everywhere, where there is a pivot point and needs restricted movement between them. For example, the control arm, leaf spring/shock absorbers, sway bar, steering column, and even transmission and engine mounts.
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2 Polyurethane vs Rubber Bushing: Which Should I Choose?
The difference between rubber and polyurethane is mainly the mechanical properties offered by each. Polyurethane bushings are more durable and stiffer than rubber and are better suited for applications such as high-performance vehicles where handling is the top priority. The rubber bushings, on the other hand, are used for a single mechanical property, which is shock absorption. Some important characteristics of rubber and polyurethane bushings are explained below. These factors will help you decide which bushing is best for you.
Ride Quality
As rubber is softer than polyurethane, it is much easier for it to absorb road irregularities, thus giving you a very plush and comfortable ride. Apart from lowering manufacturing costs, this is one of the main reasons why car manufacturers use rubber bushings as standard. Polyurethane bushings, on the other hand, provide a stiff and bumpy ride due to their hardness and lack of shock-absorbing properties. They are not designed for comfort-oriented driving, but they can be driven aggressively due to their superior traction and feedback.
Lifespan
Rubber bushings wear out faster than polyurethane bushings because they are soft. Due to constant stress applied to them, they stretch and compress, and over time, they lose their elasticity. So don’t be surprised if you have to visit the mechanic to change the bushing in a few years. On the other hand, poly bushings are harder and cope well with the forces applied to them by the suspension components. They usually outlast the vehicle they are installed on.
Hardness
One of the benefits that polyurethane bushings bring is also sort of the greatest drawback, which is hardness. The durometer hardness of a stock OE rubber bushing is between 50-60A, whereas polyurethane bushings range from 75-95A. Due to this, the poly bushings do not bend or deflect much as the original bushings, which translates to better stability for your suspension parts but also increases NVH levels. While poly bushings are on the higher side of the durometer scale than rubber, there are also solid metal bushings that you will find in track racing vehicles. This has the highest hardness level among the other two bushings on offer, and it drastically increases noise and vibration but provides the most responsive handling possible. In conclusion, polyurethane bushings take the middle ground between harshness and performance.
Maintenance
Rubber bushings require no maintenance and are completely replaced when they wear out. Lubrication is performed during installation, so no additional lubrication is required. However, unlike rubber bushings, poly bushings must be cleaned and lubricated on a regular basis in order to function properly.
Installation
Professional help is needed for the installation of rubber bushings as a hydraulic press and complete removal of the affected linkage are required, so it’s definitely not a DIY job, whereas installing poly bushings is easier than installing rubber bushings because they usually don’t require a hydraulic press. Hence, it can be a DIY process.
Performance
When you choose rubber bushings, you are choosing comfort over performance. Rubber bushings allow more movement between the suspension components, which reduces confidence while driving because it leads to reduced road feel and feedback. So it’s definitely not for those who consider themselves non-aggressive drivers. With polyurethane bushings being stiffer, they don’t allow the suspension components to move that much as compared to rubber ones. This stiffens the entire suspension system, providing better contact between the tires and the road surface. It may not be as comfortable as the rubber ones, but the polyurethane bushing offers better performance and can take a corner with better stability.
Squeaking
This occurs when the rubber rubs against its metal housing. As rubber bushings come chemically bonded with the shell, it acts as a single unit with no chance for any squeaking. In contrast to rubber bushings, poly bushings are mechanically bonded to their shell, which allows for some movement and can cause squeaking if not properly maintained.
| Factors | Rubber Bushings | Polyurethane Bushings |
| Ride Quality | Reduces noise, vibration, and hardness (NVH) | Increase noise, vibration, and hardness (NVH) |
| Durometer Shore-A Scale (Hardness) | 70 Shore-A (softer compared to poly bushings) | 80 Shore-A (harder compared to rubber bushings) |
| Lifespan | Same lifespan as OE bushings | Last very long, often the life of a vehicle, if properly maintained |
| Oxidation and corrosion resistance | Good | Excellent |
| Weather Resistance | Fair | Excellent |
| Performance | Comfortable ride, OE style performance | Better performance, less bounce and improved road handling |
| Noises and Squeaking | Less prone to noises and squeaking | More prone to noises and squeaking |
| Maintenance | No need to grease | Has to be greased and lubricated (every 4-5 years approx) |
| Installation | Needs special tools and expertise for installation | Easy to install |
| Price | Expensive | Cheaper compared to rubber bushings |
3 When Should You Use Polyurethane Bushings?
Using polyurethane bushings can be an upgrade or a downgrade depending on the usage and the mounting location where the bushings are used. For example, using poly bushings in sway bar bushings, end links, and dust boots will result in an overall upgrade as poly bushings deflect less than rubber ones, resulting in better cornering performance and more grip. Dust boots, on the other hand, prevent debris and other contaminants from entering moving parts such as ball joints, tie rods, and so on, which can lead to premature wear. This will also benefit those who intend to use their vehicles for heavy-duty off-roading, as poly bushings can benefit them and last longer.
Using poly bushings in places like engines or transmission mounts, as well as for suspension, can improve power and handling while increasing vibrations and NVH levels.
| Type Of Driver | Recommended Bushing |
| Daily driver | Rubber Bushing |
| Trailer and hauling | Polyurethane bushings |
| Daily driver and occasional adventurer | Both are good (personal choice) |
| Need cushion comfort | Rubber bushings |
| Sporty feel and track racing | Polyurethane bushings |
In the end, it all depends on what you want and what your priority is. If you would prefer a comfortable ride or an aggressive ride that requires good handling but sacrifices comfort. Both bushings have their pros and cons, which you must weigh according to your use and needs.
4 How Do I Know If My Bushings Need To Be Replaced?
Like other consumables, bushings wear out too, and when they do, they may cause some issues and symptoms. You should know to verify it’s a worn bushing.
- Weird Sound: Sounds of creaking, rubbing, and clunking can occur when the car is pushed around corners, going through rough road surfaces, even under hard braking and acceleration.
- Uneven or Premature Tire Wear: Due to worn-out bushings, there can be an uneven load on the tire, which can lead to premature or uneven wear of your tires.
- Steering Noise: A vague or drifting feel can be felt while turning. You can even feel a play and hear a clunking noise when turning the steering wheel from left to right.
- Vibrations: Worn-out bushings can lead to metal-to-metal contact, which can lead to vibrations.
5 How to Make Polyurethane Bushings?
Polyurethane bushings are typically made by casting a polyurethane mixture into a mold. The process involves mixing various compounds to form the type of polyurethane used to produce a bushing. The mixture is then poured into a mold and allowed to cure. Once the polyurethane has cured, the bushing is removed from the mold and is ready for use.
If you’re interested in making your own polyurethane bushings, there are several DIY tutorials available online. The process involves creating a mold, mixing the polyurethane, pouring it into the mold, and allowing it to cure.
