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Founder, 1929-2014
Speedy Bill
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AFCO 42 Series Double Adjust Mono-Tube Coilover Shock, 9 Inch

AFCO 42 Series Double Adjust Mono-Tube Coilover Shock, 9 Inch

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Q & A

What's in the Box

AFCO 42 Series Double Adjustable Mono-Tube shocks truly are the ultimate track weapons!  No other shock on the market today can match the M2's innovative list of features.  The M2's ability to keep the tires in compliance with any track surface condition from tack to slick, bumpy to smooth, rutted to washboard, lies in its combination of low friction and quick reacting components. 

At the heart of the M2 is the unique bladder design.  While other floating piston designs effectively "turn off" while trying to overcome stiction and changes in direction, the M2's gas inflated bladder is able to expand and compress at incomparably high speeds, very slow speeds, very small movements, and large deflection all at the same time with virtually no resistance or friction.  The result is a feeling of being stuck to the track rather than riding over it.

Due to its unique design, the adjustments you make with the M2 have a very large effect on handling.

The M2's mono-tube, gas pressure design coupled with its superior valve design and use of gas charged bladder provide real, substantial control of compression and rebound resistances throughout the entire velocity range.  This means the M2's adjustments are much more pronounced and provide more sensitive and extended low speed adjustments for increased effective tuning range.

For pavement late models.  Includes tuning instructions, coilover kit and dyno sheet.


Includes tuning instructions, coilover kit and dyno sheet.

For pavement late models.


Low Friction

The extreme sensitivity of the M2's bladder design required a complete re-engineer of all the moving components to minimize friction.  Starting with an ultra smooth black shaft, all new low friction rod guide, continuing in the piston seals and even the fluid port's contours, every part has been made to operate as freely as possible to give the shock the best response possible.  Low friction operation not only benefits the ability to provide control, but also reduces heat build up and provides more consistency. 


Swiv-Align Floating Spring Seat

The design of the high tech Swiv-Align spring seat removes nearly all side forces from the shaft and makes the M2's damping smoother and more consistent than other shocks without any added expense.


High or Low Gas Pressure

The M2 remains hyper-sensitive at significantly lower gas pressures than the competition.  This gives you the advantage of being able to run a MONO-TUBE shock and achieve TWIN-TUBE shock feel and characteristics.  To gain all the advantages a Mono-Tube design offers, the M2 shock is perfectly equipped to handle very high gas pressures and provide precise, effective, and predictable results. 


Isolated Compression & Rebound Control

The M2's unique design allows for completely independent rebound and compression control.  This gives you the ability to fine-tune for maximum control.  The feel of AFCO's M2 100% o-ring sealed adjusters is not affected by gas pressure changes, since they use springs to control detents rather than relying on the pressure of the gas in the shock. 


  • Stroke: 9"
  • Compressed Length: 15.20"
  • Extended Length: 24.20"

Item Details

Compressed Length: 15.20"
Extended Length: 24.20"
Left Rear

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