Suspension Bushings: Polyurethane Vs. Rubber

Suspension Bushings

New cars seem to float on the road, making every bump and pothole feel like an afterthought. Wanting to keep that magic carpet feel, you get your car serviced at every opportunity. But, even with that new car air freshener and routine maintenance, it soon loses its smooth gait. Before long, you can feel every divot in the road. In most cases, a worn-out bushing is to blame. If it’s time for new bushings, you need to ask yourself one thing:  rubber or urethane?

What Exactly Is a 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’re not the only reason your car might shake, they’re 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 don’t last forever.

When Should I Replace My Suspension Bushings?

As their lifespan varies widely depending on driving style and environment, there’s no set interval for 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’s time to discuss the two main types of bushings available.

Rubber Suspension Bushings

Much more pliable than polyurethane, rubber is a great choice for those looking for a bit more give in their suspension. It’s also what comes standard on most vehicles. If you’re fine with how your car drove up until it started shaking, rubber might be the way to go. Here’s where rubber bushings stand on nine key traits:

  • Ride Quality: Because rubber is softer than polyurethane, it’s much better at warding off road noise and vibrations. This means that rubber bushings make for a much smoother ride. This is one of the main reasons—aside from cost–that OEMs use rubber ones on the assembly line.
  • Hardness: When compared to polyurethane, rubber is a lot more pliable. Until Jell-O bushings become standard, they’re likely to be the softest option on the market.
  • Lifespan: Rubber suspension bushings have a much shorter lifespan than poly ones. They’re also a lot more prone to damage from oil, UV, road chemicals, and heat. Over time, the stresses of the road cause rubber to warp and stretch. So, don’t be surprised if you’re visiting the mechanic to replace your replacement bushings in a few years’ time.
  • Squeaking: Squeaking occurs when bushings rub against their metal housings. Since rubber bushings come chemically-bonded with their shells, there’s no opportunity for movement. This means they’ll never squeak.
  • Maintenance: Aside from eventual replacement, rubber bushings are 100-percent maintenance free.
  • Installation: Installing a rubber bushing is a lot harder than installing a poly one. It usually requires a hydraulic press and the complete removal of the affected spring or control arms. Since hydraulic presses aren’t standard backyard mechanic fare, installation is best left to the professionals.
  • Feel of the Road: If you replace your old rubber bushings with new ones, you can expect the road to feel similar to what it was before they failed. For those who enjoy feeling every pothole, this is one of rubber’s main drawbacks.
  • Performance: When you choose rubber, you’re opting for comfort over performance. As rubber has a lot more give than poly, it gives you a smoother ride. But this excess suspension movement makes it harder to turn on a dime. So, rubber’s definitely a no-go for aggressive drivers.
  • Price: Though available at a discount to OEMs, rubber bushings are more expensive for end users.

Polyurethane Suspension Bushings

Once the domain of the military and racecars, polyurethane bushings did not become widely available until the 1930s. As they don’t rot or deteriorate, they often outlast the vehicle they’re put on. For anyone looking to upgrade their suspension, poly bushings are a great choice. Here’s how poly stacks up against rubber:

  • Ride Quality: Due to their hardness, polyurethane bushings often lead to a bumpy ride. Since they’re not as good at dampening, passengers are also subjected to a lot more noise and vibration.
  • Hardness: Polyurethane bushings are much harder than rubber ones. Though that doesn’t mean they’re the hardest ones available. That honor goes to the aluminum suspension bushings used by racecar drivers.
  • Lifespan: Because they’re harder, poly bushings cope a lot better with the demands of the suspension system. They’re also resistant to UV, oils, road chemicals, rust, and heat. Often outlasting the vehicle they’re installed on, polyurethane bushings are usually covered by comprehensive warranties.
  • Squeaking: Contrary to popular belief, polyurethane suspension bushings don’t HAVE to squeak.  They’re just more likely to do so. This all comes down to how they’re made. While rubber bushings are chemically bonded to their housings, poly ones are assembled mechanically. This means they have room to move, rub, and jostle against their sleeve. If not properly maintained, this can lead to squeaking.
  • Installation: A hydraulic press is usually not required to install a polyurethane suspension bushing. Once you’ve learned how to remove the old rubber bushing, installation is an easy two-step process.
  • Maintenance: Unlike rubber suspension bushings, poly ones need to be greased every three to five years.
  • Feel of the Road: Polyurethane bushings help the vehicle feel like an extension of the driver. The bumps and potholes become more pronounced. Though this is a turnoff for some, others feel that it makes them better drivers.
  • Performance: Since they don’t flex as much, poly suspension bushings can make the entire suspension system more efficient. This makes turning and cornering easier.
  • Price: Poly bushings are the cheaper of the two.

Summary

  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

 

Which Suspension Bushing Is Right for Me?

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.

No matter what you decide, Poly-Tek can help. Feel free to give us a call at 1(510)895-6001 or email us at [email protected] to discuss your suspension bushing needs.