Vauxhall Firenza Inc 2.3 Rear Lower Trailing Arm Bush:
What's wrong with rubber?
Rubber has traditionally been used for automotive suspension bushes. It has the advantages of low cost, is easy to work with, it can be used for a wide variety of applications and is able to provide a level of insulation between steel components. However, it has some significant disadvantages:
All this causes the rubber to start to lose its elasticity and as importantly its resilience. In time rubber will lose the shape it was designed to be. The car’s suspension components start to move to a position different from the ideal, with a loss of handling precision and predictability and accelerated wear of other components and tyres.
In contrast, polyurethanes, especially those manufactured using cold pour/thermo setting processes, can be resistant to all of these problems and retain its original shape. The result is a suspension bush which will last a lot longer than rubber – and will perform consistently throughout its life.
But doesn't Polyurethane have excessive Noise Vibration & Hardness (NVH)?
Traditionally Polyurethane has been associated with being a hard material, giving excessive NVH. But with SuperPro due to the unique properties of the raw material and the design techniques used in the manufacture of SuperPro Polyurethane bushes, they will not cause any extra NVH over the standard rubber bushes. This makes them suitable for road cars and race cars alike.
In addition SuperPro doesn’t generally offer different hardness’s for their location kits with colour coded bushes. The reason for this being that SuperPro believes that it is important to supply a bush that is designed to achieve the optimum performance for its location on the car – without creating a harsh or uncomfortable ride. This means that a car may need bushes of three or four different materials to deliver the best improvement in suspension performance without creating excessive levels of NVH. Colour coding by material hardness would result in either specifying multi-coloured car kits of varying hardness of materials, or kits of one colour and hardness which would compromise performance.
SuperPro bushes, while being direct replacements, are not identical to OEM. SuperPro has a complete understanding of the material being used, which requires that each bush is specifically engineered due to the nature of polyurethane. This can give SuperPro bushes a major advantage over the standard rubber versions as they can eliminate problems where the rubber bushes are prone to premature failure.
Why should I use SuperPro when it's so expensive, or is it?
While the cost of buying SuperPro may be significantly more than an OEM rubber bush, we believe that you are investing in a product that will save you money in the long run. SuperPro bushes have a long service life and their performance doesn’t degrade over time. This means that you don’t have to replace bushes as often, saving you money and time.
Secondly, while material and manufacturing costs for polyurethane are high – the cost of new product development is relatively low. With the enthusiast markets preference for ‘Whole Car’ solutions this means that the SuperPro catalogue includes many applications which are only available from the OEM or in the aftermarket as a part of a complete arm – or are simply not available. All of a sudden – what was an expensive product now looks very cost effective – often as much as 50-60% cheaper.
Also, polyurethane can be used to ‘Fix’ a weak original design where rubber is simply not man enough for the job. This can help reduce wear of other components and the need for embarrassing explanations about why the bush that was replaced last year has failed the MOT again this year!
Innovative engineering designs to suit universal applications.
The polyurethane that is specifically blended for the SuperPro product has mechanical properties that make it extremely successful in its application. The properties of extreme resistance to abrasion, low compression set, high tear strength and a resistance to oils and solvents make SuperPro’s polyurethane ideal for automotive applications. These properties lead to a resilient product that is highly versatile in its applications.
The crush tube is an integral component of the suspension bush system and is necessary for free pivoting. The crush tubes are made to precision tolerances to ensure that the precise fits are maintained.
Wherever an outer shell or sleeve is used in the SuperPro product range you can be assured that it is also made within precise tolerance ranges.
The double helix:
The double helix is a design feature that has lead to improvements in the SuperPro product. The double helix is used in two applications. The first is on the inside of the bush and the second is on the outside diameter of the crush tube.
The first design of the double helix is used primarily on shackle bushes. The double helix provides a region for grease to travel along. This allows a boundary layer of grease to form between the inside diameter of the bush and the outside diameter of the tube. The double helix is extremely successful in greaseable shackles as the grease can travel from the centre of the bush along the helix and out to the grease grooves in the head of the bush.
Knurling is used on control arm bushes to enable unrestricted pivoting of the polyurethane bush around the crush tube. The knurling has two inherent design advantages. The knurling reduces the surface area of polyurethane in contact with the crush tube. This reduction in surface area results in less frictional forces being developed. The SuperPro knurl bore keeps the lubricating grease intact for the life of the bushing, and eliminates the necessity for periodic re-greasing.
Bullet grooves and voiding:
Bullet grooves are incorporated in the design of SuperPro bushes to allow for variances in control arm or spring eyes.
The voiding and bullet grooves also allow for the transgression of displaced polyurethane into the volume of the grooves as load is applied during normal vehicle operation. Even though polyurethane is in a solid form when it is manufactured into bushes, its unique properties enable it flow in a manner similar to a liquid when loaded. The action of the bush flowing into its voids prevents the generation of harshness and NVH within the bush and its mount.
Tangential grease grooves in head:
The tangential grease grooves in the heads of shackle bushes have reduced the friction between the head of the bush and the shackle plates. The grooves store grease, which is smeared around the mating surfaces when the spring shackles rotate forming a lubrication boundary layer. This has the effect of minimising head friction and reducing noise.
Are they difficult to fit?
All SuperPro bushes can be fitted with normal workshop tools and equipment. Where necessary, grease is supplied for effective operation and to assist fitment, but in many cases the most difficult job will be removing the old bush!
What is the life expectancy of SuperPro Polyurethane Bushes?
As SuperPro’s Polyurethane material is not affected by petrochemicals, water, salt, daylight and is extremely resistant to abrasion, with normal use SuperPro bushes will last up to six times longer than original rubber components. The material also remembers it’s shape - long after a rubber bush will have ‘Set’ in a distorted position.
Do SuperPro Polyurethane Bushes come with a warranty?
Yes 3 years or 36,000 Miles (60,000Km).
Will I improve my handling by fitting SuperPro Polyurethane Suspension bushes?
Yes, by fitting SuperPro bushes you will experience consistent steering geometry, and enhanced handling and control of any vehicle as it does not deteriorate as rubber will. Due to SuperPro's unique Polyurethane material and design features, stricter tolerances can be used which will give you improved performance characteristics such as; better road holding, increased tyre life, more responsive steering, and longer service life of suspension components.
Do you recommend using grease with SuperPro bushes?
In all the locations on a vehicle where bushes have a pivoting action, it is essential that grease is used. Due to the characteristics of Polyurethane, and the way in which the bushes behave, they start to act as bearings instead of just a gap filler, and as little friction in movement as possible is vital to avoid uncomfortable increases in Noise Vibration and Harshness (NVH). All SuperPro kits include grease where necessary; of course we do not include grease where it is not necessary for the performance of the component to do so.
Does the colour of your bushes indicate how hard the ride will be when fitted?
No. SuperPro bushes are supplied in one standard colour: Blue. SuperPro believes that it is important to supply a bush that is designed to achieve the optimum performance for its location on the car – without creating a harsh or uncomfortable ride. This means that a car may need bushes of three or four different materials to deliver the best improvement in suspension performance without creating excessive levels of NVH. Colour coding by material hardness would result in either specifying multi-coloured car kits of varying hardness of materials, or kits of one colour and hardness which would compromise performance.
Should I fit SuperPro Polyurethane Bushes for motorsport applications?
Yes - including Off Road and track competition use. As SuperPro bushes offer improved handling performance over rubber, they are ideal for use in racing, rallying and other forms of motorsport. They are especially beneficial when a competition car is also used on the road and where nylon bushes or solid joints are not appropriate.
How many of each SuperPro bush kit do I need per location?
Generally only one. SuperPro bush kits are assembled to include all the components needed to replace the bushes on both sides of the car in the same location. The exception to this is if the same bush kit is used on the front and rear of the vehicle, if both the front and rear bushes are required two bush kits will need to be purchased in this situation.
I use my car daily, will fitting SuperPro make the ride uncomfortable?
No. Due to the unique properties of the raw material and the design techniques used to manufacture SuperPro Polyurethane bushes they will not cause any extra noise, vibration or harshness (NVH) over the standard rubber bushes. This makes them suitable for road cars and race cars a like.
Are your bushes a copy of the originals?
No. Due to the different way Polyurethane works. This requires the design of the bush to be different than the original rubber bush. This can give SuperPro bushes a major advantage over the standard rubber versions as they can eliminate problems where the rubber bushes are prone to premature failure.
My car has been lowered, can I still fit SuperPro Bushes?
Yes. Lowering a car actually puts more stress on the original bushes and will make them deteriorate faster. By fitting a lowering kit on your car and keeping the original bushes you will not get the best from it as the suspensions arms will still be able to move making the cars geometry unstable. Fitting SuperPro to the car help keep all the suspension arms in the correct position – even under heavy cornering. SuperPro also offers the option of caster & camber adjustment bushes which can help compensate for geometry changes as a result of lowering.
My car pulls to one side, can you help?
Yes. SuperPro has a range of caster and camber adjusting bush kits for various models. These can be used when the cars original geometry settings have gone beyond the factory adjustments.
Yes. SuperPro has many applications where the individual bush kits can be purchased separately or as a complete kit – these kits are cheaper to buy than the individual bush kits together. If there are no kits listed for your application please contact us and we will try to accommodate your needs.
Are SuperPro Polyurethane Bushes available for classic cars?
Yes, we have an extensive range of bushes available for classic cars.
If you do not have my car listed in your catalogue, could you still help me?
We may be able to match your requirements from our existing range of over 3000 part numbers. It may also be possible to modify an existing bush or we could supply you with a polyurethane billet for you to machine yourself. We also have an ongoing program of range development and expansion.
Do SuperPro make anything else in polyurethane other than suspension Bushes?
We may be able to match your requirements from our existing range of over 3000 part numbers. It may also be possible to modify an existing bush or we could supply you with a polyurethane billet for you to machine yourself. We also margin-bottom:10px; have an ongoing program of range development and expansion.
What is resilience?
Resilience is the speed at which an elastomer will return to its original shape after being deformed.