Most customers are not aware that these bushes are designed to go only one way.
They are designed like a ball joint where you have the outer casing with an acetal seat inside, then centre pin is pushed in, and the pressure plate is fitted on top. After that the top of the outer casing is rolled over the pressure plate to lock all together and to put the pin under pressure.
They are designed so the centre pin is pushed forward not backwards, if they are fitted the wrong way they will fail. If you are not sure which way they go, carefully remove the dust boot to find the end where the steel has been rolled.
Rubber vs. Polyurethane
We believe that SAS Autoparts is the largest importer of rubber parts in New Zealand and we believe that rubber is a far superior product to be fitted in most applications than polyurethane.
Firstly rubber is a natural product which makes it the most suitable material for a wide variety of applications. Rubber bushes are more compliant than urethane bushes and are more flexible which provides a smooth quiet operation. They are great for absorbing road shock, enhancing comfort, reducing noise and vibration. Rubber also has a memory so when you twist a rubber bush it will always return to its original shape. Try that with a urethane bush!!
Urethane bushes do have their advantages and we at SAS Autoparts import and sell a great range of PolyTuff bushes. But only for those who want to give their vehicle a much more ridged feel.
Honda Civics/Intergra have a 80-85mm rear trailing arm bush designed to give the vehicle some passive steering and movement in the rear wheels. Try fitting urethane in these applications then drive the vehicle around a bumpy corner and see how the car reacts. The urethane bushes are too stiff and you lose that passive steering and movement. Therefore Rubber bushes are far more suited to give that movement and retain comfort.
Most packs of urethane bushes come with a pack of grease as urethane bushes are not self lubricating. If you fit urethane to 4wd vehicles especially to leaf spring vehicles that do any kind of off road work, see what happens to the bushes when dust or sand are mixed with grease.