A car’s suspension quite literally and figuratively rides on its suspension bushings. Deciding on installing rubber bushings vs. polyurethane ones is no less a decision than choosing the difference between a smoother, quieter ride compared to a better feel in how the car handles and steers. There is that much of a difference. Both rubber and polyurethane are elastomeric polymer materials that share a few similar properties. The two materials are nevertheless distinct from one another and formulated to achieve different results in their applications. This is especially true when it comes to choosing between the two materials for bushings.
What Exactly Is a Suspension Bushing?
Car bushings are small suspension components that reduce friction between the metal parts of your vehicle. Made from shock absorbent materials, usually urethane or rubber, they are crucial to ensuring a smooth ride. Though they are not the only reason your can make shake, they are usually the prime suspect. For something that makes such a big difference, bushings are surprisingly simple. They consist of just two parts: an outer (usually metal) sleeve and a spongy interior. But, like most suspension components, they do not last forever.
When Should I Replace My Suspension Bushings?
As their lifespan varies widely depending on driving style and environment, there is no set interval for suspension bushing replacement. Instead, mechanics recommend replacing them when you notice the following symptoms:
- Excessive road noise and vibration in the vehicle
- Unusually loose steering and a pronounced lack of control
- Banging or creaking coming from around the fender
- Rattling in the frame when driving over rough terrain
Now, it is time to discuss the two main types of suspension bushings available.
Rubber vs Polyurethane Suspension Bushings
Polyurethane is often described as providing better handling while rubber gives you a smoother ride. This is a simple explanation that is correct, but there are other pros and cons that should be considered when deciding what kind of bushings, you want for your vehicle.
| Polyurethane Suspension Bushings | Rubber Suspension Bushings |
Ride Quality | More vibration and road noise | Less vibration and road noise |
Hardness | Harder and less pliable | Softer and more pliable |
Lifespan | Life of vehicle | Same as original bushing |
Squeaking | Small chance of squeaking | No chance of squeaking |
Maintenance | Greasing every 4-5 years | None |
Installation | Easy to do yourself | Requires a professional |
Feel of the Road | Enhanced feel of road | Diminished feel of road |
Performance | Improved performance | Standard performance |
Price | Cheaper to buy aftermarket | More expensive to buy aftermarket |
The Theory of Bushing Relativity
The big idea to keep in mind when considering the difference between polyurethane and rubber bushings is that individual driver preference and intended use of vehicle plays a big part in which option is best. It is a question of whether you value performance (polyurethane) more than comfort (rubber) or vis-a-versa. Wherever you find yourself on the scale between those two options will determine what kind of bushing is right for you.
Spectrum of Bushing Hardness
While polyurethane bushings are higher on the durometer scale than rubber, poly is not the hardest, least compliant suspension option available. Unless you are familiar with dedicated track racing vehicles you might not be aware that many of them use solid metal joints where you would normally find rubber bushings. This drastically increases noise and vibration but provides the most responsive handling possible – trading comfort for performance. While polyurethane (especially in the early days of the material) provides less absorption of ‘road feel’ than traditional rubber it is NOT a step from ‘comfortable’ to ‘bone-jarring’. In the grand scheme of things polyurethane really occupies the middle ground of harshness/performance as far as bushing materials are concerned.
Ride Quality
Rubber nearly always provides a quieter and smoother ride, while polyurethane increases NVH for the driver.
Road feel is not entirely negative since some people like feeling a little bit of their vehicle interacting with the road, though feeling no feedback at all when driving is usually people’s preference. In a long-distance daily commuter poor ride quality is likely to become a nuisance that rubber bushings can eliminate (though their lifespan is shorter, more later) while poly bushings on a track car or a grand tourer might be more appropriate since those drivers typically like to ‘feel’ the vehicle interacting with the road.
Suspension Bushings Lifespan
Polyurethane bushings last much, much longer than rubber.
A rubber bushing’s greatest strength is also it is weakness: It is very pliable. Even without the stress of several hundred pounds of vehicle squeezing and smashing rubber bushings they are susceptible to vehicle chemicals, road salts, costal climates, and heat. Polyurethane is a much more resilient material that withstands chemicals, heat, and other elements that destroy rubber.
Aside from the external factors, just the pressure and torque that is produced in most bushing positions will eventually wear down or destroy rubber. Also, some vehicle uses such as off-road or payload hauling are harder on the suspension and bushings making those the perfect situations to apply hardier polyurethane bushings.
Ride Feel
The basic explanation is Rubber decreases road feel while poly increases it, but this needs to be balanced against the desired performance.
Rubber isolates the driver from the road very well while polyurethane provides feedback from the road to the driver. While many folks are driving a daily commute and want the smoothest ride possible there are some who enjoy feeling the how the vehicle is reacting to the road like weekend track junkies and grand tourers.
Rubber bushings have more “give” and eliminate most noise and vibration making the suspension cushier. Poly bushings hold the suspension components tighter which is better for handling and alignment, but the downside is more vibration making its way from the road to the driver.
Driving Performance
In the realm of handling performance polyurethane bushings beat rubber easily.
The entire philosophy behind rubber bushings is their extreme compliance reduces noise and vibrations, but this also means that the rigid alignment that is required for precision handling or high-speed turns is thrown off by flexible rubber bushings allowing too much play in the suspension.
Polyurethane bushings do not flex or shift to the extent that rubber will and still provides a compliant joint for suspension components. This takes the excess suspension movement out of the equation and leaves the driver with much more responsive handling. This makes Polyurethane bushings a good option for folks who want a more performance focused experience than rubber can offer, without the soul-shaking vibrations that solid joints produce on normal roads.
Squeaking
Rubber makes no noticeable sound while polyurethane has the possibility of squeaking (if not properly lubricated).
Historically, one of the most common complaints about poly bushings is that they squeak where rubber bushings do not. While it is true that poly can squeak it is usually a result of the part not being properly lubricated during install, as all poly bushing manufactures recommend and sometimes require to avoid warranty issues.
Rubber does not squeak since the bushing is chemically bonded to the metal shell and sleeve. The torque of suspension movement is soaked up by the bushing internally, so the rubber does not move against the metal, and thus, no noise (although this does contribute to the wear of the bushing).
Poly bushings employ a free-float design where the bushing is installed directly into the housing without a metal shell and ‘floats’ there. Since the poly and metal sleeve are not bound together, if there is no lubrication, the result is a squeaking that most find annoying. The sound is easily avoided by applying grease to the bushing during install.
Suspension Bushings Servicing
Rubber bushings require no maintenance, whereas poly bushings might require lubrication after around 5 years.
The other side of this is that properly maintained polyurethane bushings generally last the life of whatever vehicle they are on while rubber bushings might need to be replaced multiple times depending on environmental factors and how many miles are accumulated.
Poly bushing design has advanced over the years and even now some manufacturers will guarantee that if their bushings are properly greased upon install later servicing will not be required. Using the correct kind of grease is imperative since some grease does not have the same staying power as other options.
Suspension Bushing Installation
Rubber bushings require advanced tools and know how, while poly bushings can easily be installed with simple tools.
Rubber bushings encased in a metal sleeve require a hydraulic press to remove and special tools to install, while polyurethane bushings can be installed with simple tools and little work. Since poly bushings can be DIY installed, replacing the original bushings can be significantly cheaper once you are able to press out the OE rubber bushings. There are even methods for removing bushings with heat that can be achieved without a press so the entire process can be accomplished from the comfort of your own garage.
Finally
The choice between rubber and polyurethane suspension bushings boils down to “more comfort” vs “more performance”.
Rubber is the stock bushing material for almost all vehicles off the lot for two reasons 1) it is cheap and 2) it provides the smoothest ride off of the lot. Rubber bushings are more desirable for daily commuting over long distances or the smoothest driving experience while polyurethane upgrades a handling for better performance and provides more durable suspension for working vehicles.
Which are best suspension bushings for your car; Honestly? It depends. For people who prefer leisurely cruises down Main Street, rubber is often the right choice. It dampens vibration much more effectively than poly and ensures a comfortable ride. Unfortunately, rubber bushings are also costlier and require replacement. If you have a lead foot, on the other hand, poly bushings are probably the way to go. In addition to their durability, they also provide increased performance and better handling.
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I appreciate you reminding me that a suspension bushing’s lifespan is influenced by both driving conditions and style. However, it would be time to replace it if you start to feel excessive vibration and road noise. I’ll definitely share this with my truck-driving pals so they have something to remember. I will also look into trustworthy stores that may be able to help them in buying one if necessary. I appreciate you sharing!