Penske vs RPM rear shock

[fuel80guy]

I've been offered a penske rear shock from a 88gsxr.
I'm looking for input on both but mostly I'd like to be educated on rear shocks.
Rob

[skymasteres]

Let the games begin...

From what I understand from available literature the fundamental operating principles of the two are the same with one important difference. The RPM shock had the inertia sensing valve in it for quick damping bypass when sudden loads are encountered. Typically characterized by bumps in the road. Randy can jump in here and correct me if I'm wrong, but from what I can see of the fork valves, there's a weight on the valving held in place by a spring that will move when the piston encounters a load that accelerates it enough that the weight's inertia causes it to compress the spring and open the valve allowing bypass to occur. This is unique to the RPM shock. It's actually really cool since by using this method less abrupt forces, such as cornering loads, do not accelerate the piston sufficiently to make the shock go into bypass mode and the loads are damped through the shim stack.
The Penske shock doesn't have the inertial valve.

[fuel80guy]

So do Randys fork valves function the same way?

[Pat Conlon]

Rather than re-explain the RPM fork valves, we saved this info. over in the Suspension Files section: http://www.fjowners.com/index.php?topic=7486.0

[racerrad8]

So do Randys fork valves function the same way?

Yes, and that bypass circuit is patented technology of the manufacture that makes RPM suspension components and the reason no other suspension manufacture can offer or manufacture anything like it.

Here is the post covering the RPM shock.

RPM Rear Shock

Randy - RPM