We use Penske Race shocks for our 1999 C5 Racer
The original 8100 series shocks have been on since 1999 and have not failed yet

Detail of their design and functions :

We use nitrogen in all our shocks as it is more stable during operation than air, especially when subjected to heat.
The goal is to keep the static rod force (the damper pressure acts to extend the damper shaft) as consistent as possible for best performance.

The nitrogen charge in gas shocks is essential to keep them working properly.
If the charge is too low, the oil will break down and the damper won't perform correctly and consistently.

Adding gas pressure above the minimum required will simulate a stiffer spring rate in the suspension as now a higher force is required to compress the shock and spring due to the added force from the gas charge acting on the cross section area of the damper shaft.
Although the shaft diameter isn't massive (5/8"), pressure acting on this will have an effect.

The canister knob affects compression damping only. If you have a knob with 6 positions.
1 = softest, 6 = stiffest.
If car is are bottoming out over big bumps or the car feels like it's moving around too much, try going to a stiffer setting.
If the car feels too harsh and lacking grip, go to a softer setting.

The rebound adjuster will be at the other end of the shock on the end of the chrome shaft.
This adjuster makes the rebound stiffer when you turn it clockwise.
This adjuster controls roll stiffness and will help if the car takes a few oscillations to settle down after a bump.

Again, if the car feels like it's moving around too much or a bit lazy on turn in, you will want to go to a stiffer setting.

If the car gets a little tail happy or light in the rear when on the brakes, you may want to add a little rear rebound.
If the car is under-steering say on corner out on power, you may want to add some front rebound.

The 8100 Series adjuster offers a wide range of compression adjustment for the serious racer.
The method in which the PENSKE 8100 adjusts compression forces is simple.

When the damper is put into a compression condition, the fluid being displaced by the shaft entering the body must pass through the compression adjuster drum and the selected orifice located in the remote reservoir.
As the knob is rotated, a drum inside the compression adjuster is rotated, aligning the chosen orifice within the direct flow of oil into the remote reservoir.
The adjustment knob is numbered, from one to six.
By clicking to the number one position, the adjuster is set at full soft (utilizing the largest hole in the compression adjuster drum).

The number six position on the knob denotes a full hard setting (oil flow is greatly restricted). This method of adjusting compression damping is ideal for most forms of racing, especially those having higher shaft speeds and displacements. The redesigned orifices make every adjustment have a noticeable "feel" and have increased the range of adjustment.

At higher shaft velocities, oil passes through the orifice in the compression adjuster drum and gets a point of "packing-up". Instead of packing-up and increasing the damping force, a valve in the compression adjuster housing allows for the oil to bleed off, making for more linear force curves.

Image of the Nitrogen tanks for front shocks mounted to upper radiator support

Attached Files Penske8100.jpgeb1.jpg
Last edited by teamzr1; 11/07/20 11:21 AM.

Team ZR-1
True Custom Performance Tuning