User Guide
OFF-ROAD CATALOG
BILSTEIN PISTON
TWINTUBE PISTON
Heat is one of the major detriments to the performance and longevity of any shock
absorber. Conventional twintube designed shocks trap the heat within the shock body
and do not let it adequately dissipate, making them prone to heat build-up, fade and
eventual failure.
By contrast, BILSTEIN’s superior monotube high gas pressure design allows the
excessive heat from the oil to transfer to the outer surface of the shock body and
dissipate more efficiently. The dividing piston also permits the oil to expand as heat
builds, preventing aeration (foaming) and viscosity loss. This allows the shock to
maintain full damping characteristics as temperatures rise.
Pressure Differentials
Shock oils contain roughly 10% gas molecules. The
compression and rebound strokes of the shock piston in the
oil column cause pressure differentials. When the piston rod
is forced quickly into the shock tube, the pressure increases
in front of the piston and decreases behind it.
These pressure differentials release gas molecules from
the oil column which forms small bubbles (foaming). The
foaming can become so excessive that damping force is
severely reduced. The shock becomes unresponsive with a
corresponding loss of vehicle control.
In a monotube gas pressure shock absorber, the nitrogen
is separated from the oil by a dividing piston. This keeps
the oil column under pressure at all times to prevent the
release of gas molecules while enabling the shock to deliver
consistent performance under all driving conditions.
The piston head design allows
independent tuning of the
compression and rebound damping
forces to provide optimum ride
comfort and performance without
compromise. It features fewer parts
than most conventional twintube
and so-called “road sensing” shock
designs. This simple, yet exceptionally
functional digressive design
contributes to the extreme durability
and long life of BILSTEIN shocks.
Teflon (PTFE) Piston Band
Large Flow Digressive Piston
Compression Valving Disks
Rebound Valving Disks
5112 Series (kit)*
Levels vehicle, increases ground clearance,
and allows for larger diameter tires. Kit includes
(2) front 5100 shocks and (2) custom tuned
springs to enhance vehicle control.
*5112 Series available for 05-’15 Ford F-250/F-350 4x4
Due to their larger tires and a heightened stance, lifted vehicles place
extra demands on a shock absorbers damping ability. The 5100
monotube design and patented digressive valving is uniquely suited to
confront these demands. On or o-road, loaded or unloaded,
BILSTEIN shocks instantly react to changing road inputs to maintain a
stable, controlled, and comfortable ride.
Product Highlights
> 46mm monotube design for consistent fade-free performance
> Patented digressive valving instantly reacts to changing surface conditions for
maximum comfort, and control on and o-road
> Vehicle specic tuning optimizes performance for ride and handling
> OEM certied mounting hardware allows for easy installation
> Zinc plated for resistance to harsh elements
> Black boot included
> Made in the USA
> Limited Lifetime Warranty
BILSTEIN’s Digressive Working Piston Assembly
Monotube vs. Twintube Shock Design
The photo on the left dramatically illustrates
the size difference between the working
piston inside a BILSTEIN monotube shock
and one found in a typical twintube shock.
BILSTEIN’s piston has 228% larger surface
area than the average conventional
twintube piston offering greater sensitivity
and superior vehicle control.
OEM Certified Shock Mounts
Each 5100 Series has extremely durable and long lasting vulcanized
neoprene rubber bushings with vehicle specific sleeves or cast crossbars.
Vulcanized
Neoprene Bushings
Crossbar Mount Large Eye MountEye Mount
Gas pressure shock, no foaming
Non-pressurized shock, foaming
One Piece Aluminum Rod
Guide & Seal
Keeps dirt out and maintains a nearly
friction-free surface for longer life.
High Pressure Nitrogen Gas
& “Floating” Dividing Piston
Nitrogen gas maintains constant
pressure against the low mass “floating”
dividing piston and column of hydraulic
oil, eliminating the possibility of oil
foaming and performance loss.
Hard Chrome Piston Rod
Features a super finished hard
chrome plated surface with
a maximum peak-to-valley
measurement of .0002mm.
Self-Adjusting Digressive Piston
Instantly reacts and adjusts for any
condition. Provides maximum vehicle
body motion control while
maintaining superior comfort.
BILSTEIN’s Industry Leading
Monotube Design
Provides superior tube
strength while maximizing heat
dissipation and shock life.
The Technology of BILSTEIN’s Monotube Design
5100 SERIES
Monotube Gas Pressure Shock Absorber
for Lifted Trucks, Jeeps and SUVs
Contact your BILSTEIN distributor for
additional applications.
5100 SERIESTECHNOLOGY DIRECT FITDIRECT FIT