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QA1 2897-4M 28 Series Shock, 15.75/24.88 Comp/Ext, 7-4M Valving
QA1 2897-4M 28 Series Shock, 15.75/24.88 Comp/Ext, 7-4M Valving

QA1 2897-4M 28 Series Shock, 15.75/24.88 Comp/Ext, 7-4M Valving

Dirt Late Model, Modified, Pavement Late Model, Mono Tube Shock Type, 7 Compression Valving

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QA1 2897-4M 28 Series Shock, 15.75/24.88 Comp/Ext, 7-4M Valving
QA1 2897-4M 28 Series Shock, 15.75/24.88 Comp/Ext, 7-4M Valving
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We estimate this item will ship on or before February 5th.
Part # 72128974M
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Important Messages:

  • This item ships directly from the manufacturer. It may take an additional 10 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.


Shock Type:
Mono Tube
Compression Valving:
Rebound Valving:
Schrader Valve:
Gas Charged:


The 28 Series shock is an expanded gas chamber shock that performs well in various track conditions. The expanded gas chamber allows the shock to provide less rod force buildup, giving the driver more feedback compared to a standard monotube shock. The 28 Series is a popular choice for modifieds, late models, super stocks and various other classes. Works best on dry to slightly rough dirt tracks and smooth asphalt tracks.

  • 2" O.D. zinc plated steel monotube body
  • Expanded gas chamber for increased feel, traction and performance
  • Deflective disc valving
  • Linear, digressive or super low digressive valving available
  • Premium proprietary blend of specially engineered oil to prevent fade
  • Racer rebuildable and revalveable for unparalleled repeatability
  • Custom valving available
  • 100% Dyno tested and serialized
  • Made in the USA

Hyperscrew vs. Sealed Hyperscrew (IMCA legal) vs. Schrader Valve

Hyperscrew (28 Series) The hyperscrew equipped shocks have a threaded round port near the bearing end of the shock body. This hole is then sealed with a small screw that has an O-ring built into it, sealing the nitrogen gas pressure inside the shock.

Sealed Hyperscrew (28A Series)

The 28A Series shocks feature a sealed hyperscrew. The gas pressure of these shocks is only adjustable by QA1 and QA1 Authorized Rebuilders per sanctioning body, like IMCA, and track rules.

Schrader Valve (28V Series)

With a Schrader valve you can easily adjust your gas pressure. Much like adding air to your car tires, the Schrader valve allows you to make "on the fly" gas pressure adjustments between heat races and features to adjust for varying track conditions.

Some parts are not legal for use in California or other states with similar laws/regulations

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