AfterMarketNews AfterMarketNews Auto Care Pro AutoCareCareerHub Brake&Frontend BodyShopBusiness Counterman EngineBuilder Fleet Equipment ImportCar Motorcycle & Powersports News Servicio Automotriz Shop Owner Tire Review Tech Shop Tomorrow's Tech Underhood Service Speedville

Raybestos Partners With Schwartz Performance To Restore Classic '69 Mustang Fastback

Raybestos has joined forces once again with Schwartz Performance to restore an American icon muscle car: a 1969 Ford Mustang Fastback. “Raybestos and Mustang are the perfect match of history, leadership and innovation. Working with the first-class...


Top 10 Brake Job Mistakes For Pads, Rotors And Calipers

Here are the top 10 brake job mistakes made by rookie technicians when replacing brake pads, rotors and calipers.   10. Not cleaning the brake slides and hardware: Just slapping new pads where the old pads once resided never works. The...


Snap-on Brightens Up Your Workspace With New Rechargeable Shop Light

Get out of the dark and brighten up your workspace with the new Snap-on ECFBAR300 Rechargeable Shop Light. With an innovative Chip-On-Board LED efficiently delivering more light while maximizing battery power, this powerful shop light is ideal for use...


Customer Loyalty to Vehicle Brands Spells Ongoing Maintenance Opportunities

Vehicle owners’ allegiance to brands should give us all something to cheer about. This is especially true for those of you who service import vehicles. Nine import nameplates — Infiniti, Land Rover, Lexus, Mazda, Mitsubishi, Nissan, Porsche, Subaru...


The Element of Trust And Its Impact on a Repair Scenario

Trust: It’s an important word, and it’s one I hear a lot behind the counter at the shop. “I know you’ll treat me right because I trust what you do,” is the general sentiment. But I’ve always wondered how deep that level of comfort goes...


Servicing Mercedes-Benz AIRMATIC Suspensions

The Mercedes-Benz AIRMATIC suspension system was introduced in 1999 on the S-Class and has subsequently been used on the E-Class and most of the automaker’s SUVs. The system employs electronically controlled air springs that provide an ideal balance...


Ingersoll Rand's 'Real Work Real Play' Sweepstakes With Gas Monkey Garage And NASCAR Rewards A Tool User With The Ultimate Fan Weekend

Ingersoll Rand, the Official Power Tools of NASCAR and a preferred tool provider for Gas Monkey Garage, has announced the “Real Work Real Play” sweepstakes to reward automotive fans who “get it done” with a weekend of fun. Ingersoll Rand is working...


Bosch Relaunches With Mobile-Responsive Design, New Layout For North America

Bosch has announced the re-launch of in North America, continuing to update all of its sites to a mobile-responsive, intuitive design. The URL contains three separate sites, featuring DIY diagnostic tools (DIY), professional diagnostic...


New Bartec Tech400Pro TPMS Tool To Be Demonstrated At NACE | CARS

Bartec USA, a North American leader in TPMS Diagnostic tools, will hold live demonstrations of its newly released Tech400Pro TPMS Scan Tool at this year’s NACE | CARS show in Detroit. Michael Rose, Bartec product manager, will conduct these demonstrations...


BMW Recognized for Engine-Building Excellence

BMW Group’s engine-building prowess was recognized with four wins at the latest International Engine of the Year Awards. The drive unit in the BMW i8 earned two class wins as well as being declared overall winner, with a further class win being garnered...


Diagnostic Dilemma: The Case of the Missing Code

When doing mobile diagnostic work, no-code stalling complaints are a major part of your agenda. In most cases, the client shop is simply too busy to duplicate the failure or, in some cases, a long test drive will yield nothing in the way of useful...


Secondary Ignition: The Art of Spark

What is a coil? From the beginning of the internal combustion engine, several different ignition systems have been used to create a high-energy spark. The most popular system, and the one that’s in use today, is a step-up coil. A coil is nothing...


Home Chassis Nivomat Shock Absorbers: Self-Leveling Monotube Ride Control Units

Print Print Email Email

The Nivomat Shock Absorber is a self-leveling monotube shock absorber developed by Sachs. Nivomat is a contraction of two French words, niveau and automatique. When translated to English, it would be level automatic or automatic level.

Nivomat shocks are used by Chrysler, Ford, General Motors, Jaguar, Kia, Mitsubishi, Saab, Volvo and other OEMs. The system is also available on the GM Suburban and Tahoe as part of ZW7 Premium Smooth Ride Suspension. Replacement units are available from Monroe, ZF Sachs and OES suppliers.

The system makes use of the mechanical energy which is generated during the first meters of driving from the relative movement between the axle and vehicle body.

An unlevel vehicle can create many problems. Extra weight on the rear axle shifts the center of gravity, which has a major impact on the ride characteristics. In critical situations, the vehicle can be very difficult to control. Under these conditions a “floaty” ride characteristic can not be considered as comfort anymore.

Other effects are increasing expenses: The tires wear unevenly and faster. Bad aerodynamics causes a higher fuel consumption. Greater strain is also placed on the axle as a whole.

In place of conventional shock absorbers, this unique system is installed on the rear axle. While providing additional roll stability without requiring any additional electronics, the Nivomat adjusts the vehicle to the optimum ride height for every load condition, thus ensuring a safe and comfortable ride.

The Nivomat system does more than just level the vehicle under load. As the load increases, the pressure inside the shock increases as oil is displaced from the reservoir to the inside of the unit, compressing the gas volume. This creates a progressive increase in spring rate and damping with little or no change to ride frequency.

The Nivomat is like an ordinary monotube shock absorber with a hydraulic piston, tube and accumulator.  There are two different configurations of the shock.  The first looks like a conventional twin tube air shock with a dust cover.  What appears as a dust cover houses the high pressure accumulator and low pressure oil reservoir.  

The second configuration has its high pressure accumulator at the top of the shock.  This reduces the overall diameter of the shock.  This allows the shock to be installed in a more confining space, such as an independent rear wheel drive suspension and can be mounted in a shaft up or down configuration as designed by the manufacturer.  The normal application for this shock absorber is for the rear suspension of a passenger car or SUV.  

What gives the shock its leveling capability is a pump mechanism and oil reservoir that can increase the accumulator pressure, which increases the shocks lifting capability. It is used in combination with springs matched to the load capacity of the shock to reduce suspension travel while utilizing more of the piston and shaft travel of the shock.  

This maintains the ride quality whether the vehicle is operated with a driver only or to compensate for passengers and luggage. The big advantage to the Nivomat is the shock absorber requires no plumbing, compressor and height sensing device to level the vehicle.  The normal movement of the suspension over a regular road surface provides enough pumping action to level the vehicle.

Leveling Components:
The accumulator can be a diaphragm or piston.  The normal pressure contained the accumulator ranges from 20 bar (290 psi) to 50 bar (725 psi).  The pump can increase the accumulator pressure from 90 bar (1305 psi to 130 bar (1885 psi).  Under driving conditions, pressure can reach 350 bar (4,424 psi).  

The control sleeve is fixed in the shaft and controls oil flow through the spiral cut and release bore in the pump rod.  The inlet valve is a one way check valve located at the end of the spiral cut in the hollow pump rod.  
The low pressure oil reservoir contains the oil used to charge the pump mechanism.  The pump is located at the end of the control sleeve and uses a pump cup, pump and balance spring.

Leveling Operation:
The Nivomat shaft and piston provide the same damping as a normal monotube shock.  The difference is that the shaft is hollow and contains the pump mechanism.  The pump is operated by the displacement of oil caused by the movement of the shaft in and out of the shock. When the piston shaft moves out of the shock, oil is drawn from the low pressure oil reservoir through the hollow pump rod and inlet valve into the pump chamber.  

Since Nivomat is mechanical, the vehicle needs to be moving before the pump starts to work and it takes about a mile to a mile-and-a-half of travel before the vehicle reaches its optimal level point.

The pump is made up of a pump cup and balance spring.  When the piston shaft moves into the shock, the oil is compressed collapsing the pump spring and expanding the balance spring to fill the pump cup.  When the shaft moves out of the shock, the control sleeve opens the spiral cut in the pump rod, and the oil is forced into the main chamber of the shock. The pump and balance spring return the pump cup to its level position.  This increases the pressure in the accumulator creating more lift to return the piston and shaft to the level position. In the level position, the control sleeve closes the spiral cut and the shock operates normally until the next inlet and pump action.

The release bore is used to return the shock to the level position when the load is removed from the vehicle.  When the shaft and control sleeve is extended out of the shock past the release bore, the oil that was pumped to increase the accumulator pressure and lift is returned to the low pressure reservoir.

When replacing a load leveling shock absorber, it is necessary to inspect both mounting points for damage and stress cracks.  All mounting hardware should also be replaced.  All fasteners should be tightened to their proper torque specifications. 

The diameter of a conventional shock absorber is 54 mm (2-1/8-in).  The diameter of a Nivomat shock can range from 60 mm (2-5/8 in) to 72 mm (2-7/8 in).  Make sure the shock is properly mounted to provide adequate clearance.  It is recommended to test the operation of the shocks by loading and driving the vehicle.

Take the following steps, making sure to comply with local safety and environmental protection regulations to recover and dispose of the oil before scrapping the shock.

Diaphragm Type (Except Mercedes Benz M Class)
1. Clamp the shock in a horizontal position using a vice with the shaft fully extended.
2. Center punch a mark 50 mm (2 in) from the top of the tube.
3. Drill a 5 mm (3/16 in) hole to exhaust the gas and oil from the low pressure reservoir.
4. Center punch a mark 25 mm (1 in) from the bottom of the shock’s tube.
5. Drill a 5mm (3/16 in) hole to exhaust the gas from the high pressure accumulator.
6. Remove the remaining oil in the shock by pumping the shaft in and out of the tube.
7. The shock can now be scraped.

Piston Type (Mercedes Benz M Class)
1. Clamp the shock in a horizontal position using a vice with the shaft fully extended.
2. Center punch a mark 50 mm (2 in) from the bottom of the tube.
3. Drill a 5 mm (3/16  in) hole to exhaust the gas and oil from the low pressure reservoir.
4. Center punch a mark 10mm (3/8in) from the top of the tube.
5. Drill a 5 mm (3/16 in) hole to exhaust the gas from the high pressure accumulator.
6. Remove the remaining oil by pumping the shaft in and out of the tube.
7. The shock can now be scraped. 

The following two tabs change content below.

Gene Markel

Latest posts by Gene Markel (see all)

Latest articles from our other sites:

Joey Logano And Pennzoil Put A New Spin On Performance

Joey Logano, driver of the No. 22 Shell-Pennzoil Ford Fusion, is best known for turning heads at the track, but has put a new spin on performance by completing 13 donuts in 60 seconds at The Statesville...More

Fel-Pro Introduces Complete Engine Sealing Coverage For 2002-'05 Jaguar 2.5L DOHC V6 Engines

The Fel-Pro Gaskets brand, manufactured by Federal-Mogul Motorparts, a division of Federal-Mogul Holdings Corp., has introduced complete engine sealing coverage for tens of thousands of 2002-’05 Jaguar...More

Customer Loyalty to Vehicle Brands Spells Ongoing Maintenance Opportunities

Vehicle owners’ allegiance to brands should give us all something to cheer about. This is especially true for those of you who service import vehicles. Nine import nameplates — Infiniti, Land Rover,...More

Top 10 Subaru Articles

We're counting down the top ten most effective Subaru technical articles ever! 10) Tech Tip: Subaru Impreza With DTCs P0705, P0851, P2746, P2750 And/Or No Crank, No Start If you receive a customer...More

Autel's MaxiSYS Elite Offers Faster Processor, New Docking Station

The MaxiSYS Elite is the latest addition to Autel’s MaxiSYS family of diagnostic tools. The new Elite features a faster processor, higher screen resolution, faster WiFi, longer battery life and Android’s...More

Save Time Installing TPMS Using Dill's Preset Torque Tools

Dill TPMS Torque Tools are designed to easily install the hex nut on the valve stem. The torque values are preset, eliminating the need to adjust a torque wrench before and after install. Dill’s...More

Top 10 Fuel Pump Fails

10. Strainer Blocks Fuel-Level Sender A fuel pump inlet strainer may be installed that is interfering with the travel of the fuel-level sensor’s float arm, which causes an optimistic fuel level...More

GMC Yukon No-Cranking Complaint: The 1,300-Mile Test Drive

This month’s Diagnostic Dilemma is about the technical and professional issues involved with attempting to diagnose an extremely random no-cranking complaint on a 2003 GMC Yukon equipped with the 5.3L...More