This document provides a technical manual for the Penske 7500 Series Damper, a high-performance racing shock absorber manufactured by Penske Racing Shocks UK. The manual covers the function, technical specifications, usage, and maintenance of the damper, emphasizing its hand-built and dyno-tested quality for optimal performance and customer satisfaction.
Function Description:
The Penske 7500 Series Damper is a sophisticated suspension component designed for racing applications. Its primary function is to control the vertical movement of the vehicle's wheels relative to the chassis, thereby managing ride height, handling characteristics, and overall stability. The damper utilizes a multi-adjustment shock design, allowing for precise tuning of rebound and compression damping to suit various track conditions and driving styles. The 7500 DA series, in particular, incorporates components made from 6000 series aluminum bodies and components for superior durability, performance, and repeatability. The hard-chromed 4130 main shaft with rolled threads further enhances strength, durability, and reduces breakaway friction. The durable ACME thread body allows for quick adjustment of spring preload, and the simple, in-line design facilitates easy installation.
Important Technical Specifications:
- Construction: 100% hand-built and dyno-tested.
- Materials: Hard anodized, 6000 series aluminum bodies and components; hard-chromed 4130 main shaft with rolled threads.
- Adjustments:
- Ride Height: Adjustable via 2 Allen screws (3mm Allen) in the spring perch to prevent loosening.
- Damping: Multi-adjustment shock with various options for rebound and compression.
- Sweep Adjuster: 20 sweeps of adjustment, operated by a pick or pin.
- Hex Adjuster: 48 "clicks" of adjustment, operated by a 4mm or 5/32 Allen-key.
- Knob Adjuster: Hand operation, with 2 options (35 or 80 "clicks").
- Stud Eyelet / Shaft Pin Allen-key Fitting: 3/32 Allen-key, 4 ½ "revolutions" of adjustment (recommended ¼ turn adjustments).
- Compression Adjuster: Typically 40 different positions of compression adjustment, with a range of 150 lbs.
- Spring Rate: Gas pressure is like spring rate, with a fine tuning adjustment of 50psi, equivalent to 5-10lbs of spring rate.
- Bore Size: Standard Penske 55mm bore size, utilizing wide array of piston types.
- Shaft and Piston Seals: Low-friction design.
- Spring Preload: Durable ACME thread body allows for quick adjustment (.100" per turn).
Usage Features:
- Ride Height Adjustment: To set the ride height, the spring preload on shocks that include coil-over springs must be adjusted AFTER installing the shocks on the car. The 2 Allen screws (3mm Allen) in the spring perch should be tightened to prevent loosening. Over-tightening should be avoided to prevent damage to the body threads.
- Dyno Graph Overview: The damper's performance can be visualized through a dyno sheet, displaying the damping curve in "Full Stiff," "Full Soft," and shipped settings "Base Line." The number of clicks off full hard for the adjuster is used to achieve the curve. For 3-Way dampers, a "COMP" for compression and "REB" for rebound before the setting is provided. "LSC" (Low speed Compression) and "HSC" (High Speed Compression) values are also indicated.
- Damper Adjuster Guide: Adjusters should not be over-tightened, as they have a positive stop. Turning the adjuster Clockwise increases damping (stiffer), while Counter-clockwise reduces damping (softer).
- Eyelet Adjuster: Used for 1-way rebound, compression, or combined rebound/compression. Typically used for rebound as standard.
- Sweep Style Eyelet Adjuster: 20 sweeps of adjustment, operated by a pick or pin.
- Knob Style Eyelet Adjuster: Hand-operated, tuning it to (+) for stiffer damping and (-) for softer damping.
- Compression Adjuster: Typically 40 different positions, with a range of 150 lbs of adjustment. A typical "B" compression stack will have about 150 lbs of adjustment range.
- Damper Track Tuning:
- Compression Adjuster: Adjusting compression affects the vehicle's response to bumps and weight transfer. "Unload" the tire by hitting a certain bump, then soften the compression adjustment. For better performance, increase the vehicle's stability and control the car more controllably.
- Rebound Adjuster: A great tool for tuning body roll. Softer rebound allows the pitch of the car from the back to the front to simply close the rebound off. Stiffer rebound provides quicker weight transfer to the rear tires.
- Corner Entry Over Steer/Push:
- To Reduce Push: Soften compression -5 clicks.
- To Increase Push: Stiffen compression +5 clicks.
- Rebound: Softer rebound allows more weight to transfer to the front.
- Corner Entry Over Steer/Loose:
- To Reduce Loose: Take grip away from the front if you don't have to. Stiffen rear rebound if the car is too soft.
- To Increase Loose: Soften rear rebound.
- Mid Corner Over Steer/Push:
- To Reduce Push: If it takes a set, then under steers, add compression to the front.
- To Increase Push: If the chassis doesn't feel like it is taking a set, or feels like you not into the track, soften the compression.
- Corner Exit Over Steer/Push:
- To Reduce Push: Add front rebound, try and hold weight on the front tires longer.
- To Increase Push: If it is still over steering, increase rear compression.
- Corner Exit Over Steer/Loose:
- To Reduce Loose: Reduce rear compression.
- To Increase Loose: Reduce front rebound.
- Gas Pressure: Gas pressure is like spring rate, with a fine tuning adjustment of 50psi, equivalent to 5-10lbs of spring rate. Adjusting gas pressure is a common adjustment for qualifying, when you need to get your tires to max operating temp very quickly.
Maintenance Features:
- Warning: Penske Racing Shocks recommends running no lower than 50 psi, as lack of nitrogen pressure can result in "cavitation," leading to loss of immediate damping and rider feel. Running pressure higher than 300 psi is not recommended, as it can result in stress fractures in main mounting components. Always check with Penske Racing Shocks technicians for recommended pressures.
- Signs of Fluid: If the area around the shaft bearing and shaft exhibits a small amount of moisture, this is normal. In order to reduce friction in the system, seal squeezes are slightly relaxed, which serves the purpose to allow a small amount of fluid to be wicked onto the shaft when the shock operates. If you see excessive amount of fluid that may "pool" on the top of the shaft bearing, you may have a seal problem. Contact Penske Racing Shocks UK representative at once.
- Loss of Gas Pressure: If the shock for some reason loses its gas charge, a tell-tale sign of reduced or no gas pressure is that the shock (without a spring) when compressed, will not return to its fully extended position, or gradually gets much slower when reaching full extension. If you have experienced a loss of gas pressure, contact Penske Racing Shocks UK representative at once.
- Service Recommendation: Pre-Race inspection for oil leak, check nitrogen pressure. 30 Hours of Track Time or Yearly - Change oil, replace O-rings, seals and valve shims.
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