Why Polyurethane Bushes?
Polyurethane has been with us as a specialised plastic for some thirty years. However recent advances have now made it possible to engineer very special properties into this exciting material. Suspension bushes are some of the most highly stressed components fitted to a motor car. They undergo enormous strains and in the most arduous of conditions with no maintenance or lubrication.
The material they are manufactured from is a rubber compound containing natural products which deteriorate with age. It becomes softer and more pliable, resisting the forces placed on it less and less. Therefore allowing more and more movement of suspension components and offering less and less control over the suspension geometry.
This in turn causes accelerated tyre wear, braking instability and poor handling. This is the single biggest reason you can instantly tell the difference driving a three year old car compared to a showroom new one. However even new cars will benefit from Powerflex bushes because of their superior design they offer much more effective control of the suspension components to a much greater extent than normal rubber items.
With the technological advances in this material it has been possible to overcome the common problem associated with harder bushes which is increased noise. By correctly engineering the polyurethane compound, bushes can be made 25-30% stiffer than new rubber items but with exactly the same noise absorbing properties. Powerflex bushes make sense.
- What are suspension bushes for?
- Why are they made of rubber?
- Do racing cars have rubber bushes?
- Can I fit Powerflex bushes to my racing car?
- Why not Nylon bushes?
- If Powerflex products are this good why do car manufacturers use rubber and not polyurethane?
- Why do I need them then?
- I only have a fairly basic saloon, why do need high performance bushes?
- I love my car, it is a classic…What can they do for me?
- How much do they cost?
- Are they easy to fit?
- Where can I buy them from?
- Do I need to buy the whole car set?
What are suspension bushes for anyway?
Suspension bushes are fitted to cars at all points where the vehicle chassis is joined to a moving suspension component. They are fitted to provide a noise and vibration absorbing barrier between the road and you.
Do racing cars have rubber bushes?
In general the answer is no. A lot of racing cars, especially single seater track based cars use metal joints which do not provide any noise absorbing. The life of these joints is measured in hours. They are not suitable for road use. However a huge number of racing cars still use rubber bushes. These are either production based cars adapted for race use or rally cars where the forces on the suspension can be so high that metal joints would break.
Can I fit Powerflex bushes to my racing car?
If your race car has rubber bushes anywhere in the suspension then fitting Powerflex bushes will improve all aspects of it’s handling. They will outlast rubber by a factor of ten. They will control the geometry much more accurately during rapid suspension movements and they will reduce tyre wear.
Why not Nylon bushes?
Nylon is probably the worst of all worlds. When a suspension arm moves up and down it does not move only up and down but describes an arc. This means that, for example an inner track control arm bush will be required to flex in two dimensions at the same time. In this example a metal bush will allow this movement as will a rubber or Powerflex bush. However a nylon bush will allow up and down movement but 100% of the arc loadings will be transferred into the arm and the chassis. This causes arm flexing and can easily cause premature arm failure! Of course nylon has no vibration absorbing characteristics at all, so all vibration is transferred up the already highly stressed arm.
If Powerflex products are this good why do car manufacturers use rubber and not polyurethane?
Cost, availability and marketing. Polyurethane, as a raw material is about ten times the cost of rubber plus it is more expensive and slower to process. Car manufacturers buy a lot of components. If Ford decided to use polyurethane bushes in their range of cars they would need to find a supplier capable of making literally millions of bushes a year. There is no company in the world (even EPTG Ltd) who could make those sort of quantities. Cars are all about marketing. As long as the standard rubber bushes work without serious failure for two or three years then the manufacturer is happy. Would fitting of polyurethane bushes make you buy one car in preference to another make? Probably not.
Why do I need them then?
Powerflex bushes improve your cars’ road holding and chassis performance by controlling the amount of unwanted flex in the suspension. This means your suspension is doing what it is supposed to. It means your tyres have greater contact with the road at all times therefore improving safety and performance. Correctly formulated polyurethane is as good if not better at noise, vibration and harshness suppression when compared to rubber.
I only have a fairly basic saloon, why do need high performance bushes?
For exactly the same reason as above but with a different emphasis. If your tyres are in better contact with the road and your suspension movements are being controlled more accurately then tyre wear will be dramatically reduced. We have letters of recommendation from customers who state that they have doubled the life of their tyres on certain cars after fitting Powerflex bushes. We are not claiming that you will get this but worn bushes are dangerous and will be costing you money due to premature tyre wear. Have you ever taken your car into a tyre shop with tyres which are worn out on the inner or outer edges but perfectly legal everywhere else? You assume the tracking is wrong, but when the shop checks, it is correct. This is bush wear. When the car is stationary the tracking is correct but as you move and the loads increase then the tracking goes out. Come to a stop and the tracking is right again. Worn bushes.
I love my car, it is a classic…What can they do for me?
Another major advantage of Powerflex bushes is life. Rubber is a natural product and deteriorates with age, especially on cars which are not being used regularly. The bushes will crack on the outer surface and soften inside. Powerflex bushes are not affected by ultra-violet, petrol, oil, battery acid, water or time. Prefect for your loved one. (And the car.)
How much do they cost?
Typically about 5 to 8 times the cost of a standard rubber bush. However that is not the whole story. When you consider the cost of fitting new bushes and the fact that Powerflex will be the last bushes you every fit to your car things start to look a bit better. Then consider tyre wear, a real cost saving here. Car manufacturers have a habit of not supplying the bushes on their own, only supplying them complete with suspension arms. Paying £70 for an arm when a Powerflex bush might cost £15 is not a good idea. And finally as cars get older manufacturers stop supplying certain parts. Imagine your car was off the road because of a bush failure. You go to the parts shop and the part is “no longer serviced”! Powerflex makes a lot of sense then.
Are they easy to fit?
We design all the bushes so that they can be fitted without special tools. However sometimes it is a lot harder to remove the old bushes than fit the new ones. If you feel you have very little mechanical knowledge, experience, talent or tools, either ask a friend or get them professionally fitted.
Do I need to buy the whole car set?
No, but it depends on the car. Some cars benefit more than others. But there is a fair amount of effort involved in changing bushes so consider changing, for example a front set at one time, followed by the rear ones if applicable. Best to change the whole set if you can afford it though. (But we would say that wouldn’t we!!)
Other Powerflex products
Powerflex bushes improve your cars’ road holding and chassis performance by controlling unwanted flex in the suspension
Powerflex have developed a range of high performance closed cell foam spring aids.
Powerflex polyurethane exhaust mounts are available in various sizes and shapes, ensuring that here is one to fit your car