In sixty days, starting July 1st, Mazda Motorsports will discontinue the older smooth-bodied Penske Racing Shocks (PRS) for Spec Miata (SM), moving in favor of the threaded-bodied shock preferred by racers. This transition is a cost-saving measure aimed at maintaining competitive pricing for larger production runs of the updated threaded shock.

Announced in 2020 as an option for the Spec Miata shock body, the threaded-bodied shock was enthusiastically received by racers, as it simplified the original components of the older shock.

The treaded-bodied shocks provide numerous benefits:

• Eliminated a separate coil-over sleeve to integrate it into the shock in order to eliminate the spring contact/wear on expensive components and improve heat dissipation:
  1. Reduced wear. The new coil-over-shock allows for the proper amount of clearance between the spring and more expensive aluminum components. Because the ride height adjustment threads are machined directly on the shock body, there is increased clearance to the spring. The spring is also properly guided by a plastic component, which is more typical in motorsports. The slippery plastic component is meant to properly guide the spring coils as the suspension compresses. This smooth operation reduces wear and provides smoother spring operation for better performance.
  2. Improved heat dissipation. The elimination of a secondary threaded ride height collar covering the body of the Penske shock allows for better heat dissipation. The extra thick aluminum collar is like wearing a winter coat in the summertime, increasing running temperatures, and potentially causing the shock oil to break down faster. More consistent performance and longevity should result from a more efficient design.
• Integrated a new ride height adjustment system to offer more accurate ride height adjustment:
  1. The new, integrated ride height coil-over system provides a more positive, accurate method of adjustment. The first version by Penske Racing Shocks (i.e. the two-piece collar system) allows for the potential of ride height adjustment error as there was potential for the collar to rotate during adjustment. The integrated coil-over system is standard in motorsports because every turn of the ride height adjuster results in an accurate, repeatable spring preload. Pervious adjustment equaled 0.125” of vertical movement per turn; the new coil-over system is 0.100” per turn.
• Added self-locking hardware to remove the complication and hassle of locking screws:
  1. The included Penske ride height adjusters include tool-free locking features to simplify adjustments. Adjusting ride height has been made easier by quickly unlocking and re-locking the adjuster without tools.

Smooth Bodied Shock Part Numbers (limited availability until July 1^st):

• Front: 0000-04-5275
• Rear: 0000-04-5276

Price: $249

Threaded Bodied Shock Part Numbers:

• Front: 0000-04-5275-TB
• Rear: 0000-04-5276-TB

Price: $336

Threaded Body Coil-over install instructions are found here
Threaded Body Urethane isolator install guide found here