The Bilstein B6 Performance 24-131759 is a rear monotube gas-pressure shock for the NC-generation Mazda MX-5 Miata. The B6 line replaces original equipment dampers with a performance-grade upgrade that pairs directly with your factory springs. That makes it a handling upgrade that keeps the stock spring rate and ride height. Owners on user forums say the B6 damping characteristics are different from, and better than, the OE Bilsteins. Opinions on ride comfort vary, so it is worth reading owner feedback before buying. The monotube layout, which the manufacturer ties to its Monotube Gas-Pressure Architecture, is the main reason to pay more than for a generic rear shock. Searches for NC Miata rear monotube shock, B6 Performance rear damper, and 2006 MX-5 rear shock upgrade point to this part.
Owners on user forums report that the rear shock design is the same for model years 2006 through 2015 of the NC Miata. Confirm your exact vehicle and trim with the manufacturer before ordering.
The manufacturer states that the B6 Performance dampers are designed to be used with the original equipment springs, so replacing the springs is not required for this part.
Owners on user forums report that disconnecting the rear control arms during the swap raised the rear ride height by about 1.5 inches, and that a professional alignment was needed afterward.
Rear replacement is a moderate DIY job. Owners on user forums describe loosening the upper shaft nut from the trunk before raising the car, then removing the shock and spring as one assembly, sometimes with the top hat left in place and sometimes with a spring compressor. Some owners also disconnect the sway bar links and loosen the rubber-bushing bolts so the suspension can reach full droop. Mazda's service information warns that the shock and coil spring can fly off during removal, so take care. Torque specs should come from the factory service manual, and expect to have the rear alignment checked afterward.
