Should I upgrade to polyurethane bushings?
Polyurethane bushings make the chassis more precise by deflecting less under load. They also transmit more noise and vibration, need maintenance, and can bind where a rubber bush was designed to twist. On a road car they make sense in some locations, not everywhere.
What a bushing does
Suspension arms are mounted to the body or subframe through bushings: a sleeve, an elastomer, and an outer shell. The elastomer isolates noise and vibration and allows controlled compliance — for example letting a wheel move slightly backwards over a bump, which the engineers count on for ride comfort and sometimes for steering behaviour under braking.
Rubber vs polyurethane
Rubber bushes are bonded to their sleeves and work by twisting. They are quiet and compliant, but they age, crack and soften with heat and oil. Polyurethane is harder (typically 70–95 Shore A) and usually not bonded: the arm rotates on a greased sleeve. Less deflection means the suspension geometry stays closer to its design under load — sharper turn-in, less vague braking and acceleration, more consistent alignment.
The downsides
More noise, vibration and harshness reach the cabin. PU bushes can squeak if not greased and need periodic re-greasing. In locations where the arm moves in more than one axis, a hard PU bush can bind, loading other joints and mounts. And some compliance was there for a reason: removing it can change steering feel or tramlining on rough roads.
Where it makes sense
On a road car: anti-roll bar bushes, some subframe or gearbox mounts, and arms that move mainly in one axis. On a track car: polyurethane or spherical bearings in more locations, accepting the noise. Spherical bearings remove compliance completely and need inspection more often.
See alsoSuspension Repair & Upgrade →Performance Parts Installation →