ExtReme Camaro/Firebird 1970-1981 Independent Rear Suspension


Upgrade your Pro Touring car with the Speedtech Performance Independent Rear Suspension (IRS). This ExtReme rear suspension is designed to handle all driving conditions with ease, making it ideal for daily driving, touring, and performance driving days. The shock motion ratio >100% means you get better comfort at the same time you are gaining better performance and tire compliance with the road surface for a customizable driving experience. The complete package includes everything you need and is supplied with, JRI Speedtech Performance custom valved single adjustable coil over shocks. The exclusive ExtReme forged spindles use a sealed maintenance free double bearing.



  • Box welded construction with tabbed through frame gusseting for added torsional rigidity
  • Choice of two different IRS systems, Low Mount Shock and High Mount Cantilevered Shock
  • Significantly increased rear shock motion ratio allows for better rear grip with lower spring rate
  • Fully adjustable rear wheel alignment – Camber, Toe, Bump-Steer
  • Exclusively equipped with forged 7075 Aircraft Aluminum ExtReme rear spindle
  • Industry leading design for adjustable roll center
  • Excellent comfort on the street, durable for autocross & track days
  • Increased shock length providing more suspension travel
  • 110% motion ratio for more precise shock control
  • Sway bar arms are 3 position adjustable for tuning without changing bar
  • Rear ride height adjustments accommodate your vision for styling of the finished car
  • Rear Roll Center is adjustable over based on lower control arm mounting position
  • Dutchman 9” alluminum center housing
  • Half-shaft axles using 35 spline RCV-934 C.V. Joints rated to 1200 HP (option for 1800 HP rating)


  • 55.5″ Hub to hub width of rear suspension
  • Custom designed upper and lower control arms are the longest in the industry
  • JRI Speedtech Performance custom valved single adjustable coil over shocks, spring rates of your choice included
  • Exclusive ExtReme forged spindles with C7 hubs and maintenance free sealed bearing
  • Billet aluminum High Mount actuating rocker arms (high mount system only)
  • Speedtech Performance exclusive ExtReme forged spindles
  • 35 Spline Inner Stub Axles
  • Outer C7 33 spline stub axles
  • 33 spline EMPI 934 CV Joints
  • Hy Tuff 1/2 Shaft Axles
  • Dutchman Aluminum Housing
  • JRI single adjustable coil over shocks valved for Speedtech Performance,  JRi springs with your choice of spring rate
  • All IRS packages come standard with E Brake


  • Splined adjustable 3 piece rear sway bar
  • Rear end center section with your choice of final drive ratio
  • Aluminum Third Member with your choice of gears
  • Brake packages from Baer or Wilwood with or without E Brake
  • Forgline Wheels with custom offsets and tires