A Brief Guide to Polyurethane Bushings

Bushings are an integral part of numerous car components, mostly in the suspension department. Their ability to isolate vibrations and give otherwise rigid components some flexibility is paramount for the overall driving experience. Although rubber bushings are considered the norm, polyurethane bushings are often considered a much better option. Is there any truth to this? Are poly bushings really the be-all, end-all solution? Let’s find out!

What Are Bushings?

Your average suspension system is comprised of various components whose purpose is to keep the wheels on the ground while neutralizing any bumps in the road. As a result, the driver and passengers can enjoy all the grip without having their internals rearranged when their car hits a bump. All of those components are made of metal. Metal on metal contact creates vibrations and friction that is both uncomfortable and overall detrimental to the overall system.

bushing is there to reduce these vibrations while connecting different suspension components. A bushing is nothing more than two pieces of metal sandwiching a rubber or poly mass.

Poly Bushing softness

Rubber or Polyurethane Bushings – What’s the Difference?

If there’s one type of material that’s known to soak up vibrations, it’s rubber. This natural material has been used in bushings since they were first invented. The properties of rubber fit the mission perfectly. 

  • It’s durable enough to sustain the stresses on a daily basis 
  • it offers good isolation
  • it’s abundant. Proparts polyurethane control arm kit 101K10129

However, rubber is often soft. Soft bushings translate to increased play in the suspension system. That play can have a negative effect on how the car drives if you’re looking for top tier performance. If that’s the case, poly bushings might be a viable solution.

Polyurethane is an interesting material. Many drivers are convinced that all poly bushings are hard as a rock. The truth is that they most definitely can be, but not all of them are. Installing poly bushings on your car can definitely tighten up your suspension system.

If you go for stiff bushings, your car will handle better. However, it will also become less comfortable. On the other hand, if you go for soft bushings, you’ll end up in the complete opposite situation.

Subframe Bushing Set - Front (Polyurethane)
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Poly Bushings Hardness – the ‘Shore A’ Durometer Scale

Nailing the right hardness of a polyurethane bushing can be a pain. As it turns out, you don’t always get to know how hard they are. Different brands use different configurations, leaving us with plenty of guesswork. However, a few notable brands will tell you how hard their bushings are.

Determining the hardness of a bushing is done using the ‘Shore A’ durometer rating. This scale goes from 0 to 100 and covers everything from a soft gel to hard plastic.

Your average OEM bushings are right around 50A to 70A on the durometer scale. Poly bushings start from around 70A-80A and go all the way up to 100A. Your job is to figure out how hard you’re willing to go.

70A durometer value is considered to be almost perfect for street use. These bushings are solid enough to positively impact handling, but not too hard where you’re breaking kidney stones on potholes. If you want super stiff bushings, going with 90A to 100A will get you that racing configuration where handling comes first.

Are Poly Bushings Worth It?

This is one of the most frequent questions people have when looking into polyurethane. The fact of the matter is that polyurethane does offer several benefits that rubber simply can’t. And it’s not all about performance either.

Oil and other automotive fluids/lubricants can easily degrade rubber. Getting your bushings compromised due to an oil leak or simply grime collected from the road will reduce their lifespan. With polyurethane, you don’t have those problems. This material is not affected by oil, gasoline, or other chemicals.

Then there’s the obvious performance boost. Harder bushings equal to better handling. Going for a racing hardness level of 90A to 95A can reduce negative camber from 2.3 degrees to around 1.7 degrees when taking a hard corner. That may not look like much on paper, but that difference is tangible when you’re behind the wheel.

Torque Rod Mount - Lower (Polyurethane)
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How Long Do Polyurethane Bushings Last?

The thing with polyurethane is that it works differently than a rubber. Where rubber bushings act strictly as a damper, polyurethane ones work more like a bearing in some ways. Such a different approach to reducing noise, vibration, and harshness (NVH) means that poly bushings require some assistance if you want them to last.

To be more specific, you’ll need to make sure that they are properly greased up using synthetic grease. Most manufacturers actually ship the grease as a part of the kit. Adding grease reduces friction between the poly parts and the metal bits. If you let the polyurethane dry up, it will start to degrade while risking the corroding of the metal parts.

The next logical question is: how long do ply bushings last? With proper maintenance, they can last a long time. However, this also depends on the hardness you’ve chosen and the quality of polyurethane.

Spring Plate Bushing Set - Rear (Polyurethane)
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How to Find the Right Bushing for Your Car?

Here at eEuroparts.com, we’re continually working on making our store more accessible and easier to navigate. Finding the right part for your car comes down to typing in your car’s year, make and model or using our VIN tool. Both of these options will give you a custom-tailored list of parts that match your car. The only difference is that you can enjoy a more accurate list with the VIN tool.

If you are still unsure whether some of our poly bushings fit your vehicle, feel free to get in touch with us. We’re standing by to help you with whatever questions you might have.

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2 thoughts on “A Brief Guide to Polyurethane Bushings
  1. forkythefoz

    I just installed Powerflex bushings on my sf forester, I’m hearing creaking occasionally but everything feels great. I’m assuming that’s then setting in after install? Any experience?

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