what are the locking collars used for?
-jOnbubz
Like many other modern RWD cars, the rear suspension components and differential are mounted onto a subframe. The subframe is then attached to the base of the chassis via four bolts. Rubber bushes are sanwhiched between the chassia and subframe and tighted by the 4 bolts.
The rubber bushes provided as insulation materials to absorb NVH from suspension and drivetrain for comfort and silence in cabin. However, it caused the rear of Silvias to loose feedback and steering response. Even in high speed (> 220kn/h) cruising, the rear wheels gives the creepy feel of wobble left and right.
To nurse the issue, many Japanese tuners offer bullet aluminium alloy collars to be slotted into the rubber bush locations. This clever approach eliminates the need to change the rubber bush material yet acheive a tight feel for the rear suspension. However, the down side is that more NVH now gets transmitted into the cabin.....hehee.