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QA1 RCK52448 Mod Series GM G-Body Rear Pro Coil System, 220 lb.
QA1 RCK52448 Mod Series GM G-Body Rear Pro Coil System, 220 lb.

QA1 RCK52448 Mod Series GM G-Body Rear Pro Coil System, 220 lb.

78-81 Buick Century, 170 lbs. Spring Rate, Double Adjustable Shock Adjustability, Anodized

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QA1 RCK52448 Mod Series GM G-Body Rear Pro Coil System, 220 lb.
QA1 RCK52448 Mod Series GM G-Body Rear Pro Coil System, 220 lb.
QA1 RCK52448 Mod Series GM G-Body Rear Pro Coil System, 220 lb.
QA1 RCK52448 Mod Series GM G-Body Rear Pro Coil System, 220 lb.
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Part # 721RCK52448
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Spring Rate:
170 lbs.
Shock Adjustability:
Double Adjustable
Shock Body Material:
Shock Body Type:
Upper Shock Mount:
Bushed Eyelet
Lower Shock Mount:
Bushed Eyelet
Height Adjustable:
Number of Valving Selections:
Coilover Kit Included:
Coilover Springs Included:
Hardware Included:
MFG. Part #:


QA1 offers bolt-in Rear Coil-Over Conversion Kits for 1978-1988 GM G-Bodies. These kits include specially designed USA-made mounting brackets, MOD™ Series adjustable aluminum shocks, high travel springs, and all necessary hardware.

Single adjustable shocks provide 18 positions of simultaneous rebound and compression adjustment while QA1’s double adjustable shocks provide 18 positions of compression adjustment and 18 positions of rebound adjustment, for a total of 324 possible valving combinations. MOD™ Series shocks also feature a double adjustable design but include adjustable low-speed bleed as well for fully independent control over compression and rebound characteristics.

These shocks also utilize a fully threaded body allowing for ride height adjustability. Multiple spring rate options are also available and have been successfully tested in various applications, from casual street driving to hard core race applications.

With our highly popular adjustable struts and the addition of the Rear Coil-Over Conversion Kit, you can now get a complete suspension makeover for both ends of the vehicle.

  • Made in the USA
  • Easy, Bolt-In Installation
  • No Cutting or Welding
  • Threaded Body
  • 100% Dyno Tested and Serialized
  • Rebuildable and Revalveable by the QA1 Factory or QA1 Authorized Service Centers

Additional MOD™ Series Features:

  • Features QuickTune™ technology - modular valve packs that allow for completely revalving the shock without having to remove it from the car!
    • Medium compression and rebound valve packs standard
    • Soft or firm compression and rebound valve packs also available
  • 24 click independent compression and rebound adjustment with low-speed bleed
  • Large solid piston (with blow-off valve) for improved driver feel and control with up to 1,600 lb. force
  • High-speed valving adjustment (coarse adjustment)—relates to shock operation during impact events, like hitting a pothole or curb 
  • Low-speed valving (fine-tune adjustments)—adjusts ride quality and weight transfer on corner entry/exit; more bleed for softer feel and less bleed for stiffer feel
  • Indexable base eyelet—multiple mounting positions to optimize knob access and provide more mounting flexibility
  • Thrust bearings included

Pro Coil Systems include:

  • 2 Shocks
  • 2 Springs
  • All Mounting Brackets and Hardware


The chart below is a general guideline for selecting spring rates for QA1's Rear Pro Coil Shock Systems for 78-88 GM G-bodies. Spring rates may vary depending on applications, usage, and personal preference.

1978-1988 GM G-Body
Soft Medium Firm
170 200 220


Fits: 1978-1988 Monte Carlo, Grand National, Regal, and Cutlass

Part Numbers
Ride Feel MOD™ Series Adjustable
Soft RCK52448
Medium RCK52449
Firm RCK52450


Installation instructions for 78-88 GM G-Body Rear Pro Coil System

MOD™ Series Shock Installation and Quick Tuning Guide

**MOD™ Series shocks include thrust bearings, spanner wrenches sold separately

Important Messages:

  • This item ships directly from the manufacturer. It may take an additional 5 business days for QA1 to ship this item.
  • Get FREE shipping when your order includes this item and exceeds $99! Ground shipping only in the contiguous US.
  • This item ships via Ground Shipping only. Expedited and Air shipping options are not available.
Some parts are not legal for use in California or other states with similar laws/regulations

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Q & A

Videos & Articles
  • In this episode, Project Chevelle gets coilovers and a much-needed altitude adjustment. Watch as we install QA1 bolt-on coilover kits front and rear, then dial in the perfect stance and shock settings. Our old Chevelle is really starting to look mean!
  • Learn the proper method of blocking a race car in this step-by-step procedure to follow when performing this task. Learn why consistency is important and a few "not-to-do's".
  • Speedway Motors employee Steve is back to work on his 1976 Chevrolet Laguna, this time installing a QA1 Coilover kit in his front suspension.
  • Product guru Jeff K. takes us along as he updates the suspension on his 1946 Ford Sedan Delivery with a set of fresh Mustang II coilovers following an unfortunate incident with a pothole.

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