Home Mercedes-Benz Repair Mercedes-Benz W124: 1986-95 Owner's Bible
2002 Robert Bentley, Inc. We encourage visitors to link to this page if you’d like to share this information with others. Please do not copy this excerpt to other web sites. It is protected by copyright and represents significant resource investment by Bentley Publishers.

Chapter 1: Introduction to the E-Class
(first 10 pages)

General

  • "The Mercedes-Benz 300E, the first new midsized sedan in nine years from the world’s oldest automaker and the first Mercedes offered in North America with a 6-cylinder gasoline engine since 1981, arrives this week," read the November 7th, 1985, press release from Mercedes-Benz of North America.

While this sounded like any other automotive press release for a new model, the introduction of the new E-Class marked a permanent change in how buyers and critics alike would look at Mercedes-Benz and its midsized product line.

In 1984 the"W124" chassis was introduced in Europe to an eager motoring public. Only 3,484 cars were built that year, but the car was such an initial sales success that 159,987 were sold in 1985. Orders came in so fast that the European market was sold out for a two-year period.

  • In Mercedes-Benz literature the E-Class is often referred to as the "W124" or just the "124" chassis. This is the factory’s internal designation for the 1986 through 1995 E-Class series of cars.

The great sales success plus the time needed to develop the North American versions delayed the US introduction until the 1986 model year. Worldwide sales continued to climb, totaling 259,000 in 1986 and 271,339 the following year. Sales were so good that waiting lists developed at Mercedes-Benz retail stores around the United States.

Like the earlier Mercedes-Benz midsized sedans, the E-Class was a premium automobile engineered like no other car in the world. The new model delivered standards of safety and sophistication unmatched by any manufacturer at that time. Performance varied from reasonable to spectacular, depending on the offering.

The new 300E delivered many of the things Mercedes-Benz buyers had been eagerly awaiting. With 177 horsepower and 188 foot-pounds of torque, the silky smooth 6-cylinder gas engine propelled the car from 0 to 55 mph (the national speed limit at the time) in 7.5 seconds, with a top speed over 135 mph. The three-liter engine was the only offering in 1986, but additional powerplants were not far off.

Body Exterior

  • The new body shape was smooth, flowing from front to rear with very few "steps" for the air to tumble over. With the steeply raked front and rear glass, the exterior shape was a pleasing departure from the staid Mercedes-Benz styling cues.

Noise reduction and improved fuel economy were two key design objectives for the new chassis. Detailed wind tunnel work did much to reduce interior noise levels, while simultaneously reducing air resistance to 0.31 Cd (coefficient of drag). The new chassis represented a 27% aerodynamic improvement over the earlier W123 chassis.

The undercarriage was also analyzed in the wind tunnel. The floor pan and other components were designed flat and smooth. This included a protective belly pan under the engine, aerodynamic covers for the lower suspension components, and a panel covering the electric fuel pump assembly. Even the shape of the exhaust system was optimized for drag.

  • Aerodynamic lift is an important consideration when developing an automotive chassis. When excess under-car lift is present, the car becomes lighter on it"s axles. This adversely affects vehicle balance, handling, and passenger safety. Through deliberate body design, aerodynamic downforce can counteract the aerodynamic lift. Automotive design engineers constantly seek the ideal balance of lift, down-force and drag, while maintaining a visually attractive design.


Safety

Body structure

Many structural safety features were developed for the E-Class chassis:

  • Side impact protection consists of two structural crossmembers beneath the front seats, one under the rear seat, and one at the base of the windshield (arrow).

The crossmember below the windshield also serves to prevent intrusion of the engine.

  • In 1973 Mercedes-Benz found that most frontal collisions do not occur straight on, but rather as offset impacts where the cars meet at an angle. Collision data revealed that 40% or less of the frontal area of the vehicle is involved in the impact.
  • A forked load bearing front end structure was developed to divert impact forces and also help prevent intrusion into the passenger compartment. During an offset-frontal impact, a substructure of reinforced steel panels serves to deform the body progressively and redistribute the kinetic energy. Through this structure, the incoming loads are shared by both sides of the body unit rather than concentrated to one side.

Other features contributing to vehicle safety:

  • Fuel tank located above rear axle for rear end impact safety
  • Structural body and chassis reinforcements with ten high tensile-strength crossmembers for superior cabin protection
  • "Safety cell" passenger compartment with front and rear body sections designed to crumple and absorb energy
  • High-strength low-alloy (HSLA) steel panels and formed stiffeners in the underbody and doors for increased rigidity
  • Bumper mounted crossmembers welded to side members for dissipation of offset-frontal impact forces.


Supplemental Restraint System (SRS)

At the time of the model’s US debut, the standard Supplemental Restraint System (SRS) included a driver side airbag in the steering wheel and pyrotechnic seat belt tensioners for driver and passenger.

  • A passenger side airbag was available in later years.

The airbags are the "supplemental" restraint component of the system because the seat belts are the primary restraint in a collision. For airbags to work effectively, seat belts must be worn at all times.

  • The driver side airbag is located in the hub of the steering wheel. The airbag is constructed of a cloth bag folded in a particular way, inflated by a solid fuel gas generator integrated in the airbag unit. The ignited fuel burns very rapidly to instantaneously inflate the bag. After deployment, the gas rapidly escapes from four vents in the bag.

Beginning in 1990, a passenger side airbag was available as an option and later installed as standard equipment. The passenger airbag uses two gas generators. The generators are not fired in unison. The first is activated simultaneously with the driver’s bag and the second 15 milliseconds later.

  • The main components of the SRS are:
  • SRS light in instrument cluster
  • SRS impact sensor
  • SRS control module
  • SRS airbag(s)
  • Seat belt tensioners

The SRS light in the instrument cluster illuminates for about two seconds when the vehicle is started. This is a self-check of the SRS circuit. If a problem is found, the indicator light stays on and the SRS system is disabled.

The SRS impact sensor is mounted on the center tunnel of the body, behind the ashtray. The sensor electrically signals the SRS control module when a programmed deceleration threshold is reached. This signal is the basis for activation of the airbag(s). All the electrical contacts of the airbag system are gold plated to eliminate the possibility of corrosion and electrical resistance.

Crash research has shown that static seat belts are inherently loose and seat belts do stretch. Belt slack is also an integral part of the belt retractor design. Crash analysis further revealed that in severe collisions many drivers suffered steering wheel or windshield injuries even when seat belts were worn.

  • The E-Class features an automatic tensioning system that incorporates gas-generating (pyro-technic) technology. The tensioner retracts up to five inches of belt when the airbag is triggered. The combination of airbags and seat belt tensioning has made the cabin of the E-Class car a safe place to be in today’s harried driving environment.


Chassis and Suspension

This heading covers the various integrated electronic braking (ABS) and traction-enhancing systems (4MATIC, ASD and ASR) as well as the front and rear suspension information.

  • For more detailed information on braking, traction, and suspension systems, see Chapter 9 .

ABS (antilock braking)

ABS is the German acronym for Antiblockier System or anti-block system. ABS was first available in European Mercedes-Benz passenger cars in 1978. ABS became standard equipment on all Mercedes-Benz cars sold in the United States and Canada in 1986. The system has proven to be trouble-free and highly reliable.

  • ABS components include an electronic control module, a hydraulic control unit, and speed sensors at the wheels.

  • When the wheel is rotating, the wheel speed sensors output a voltage proportional to wheel speed. The control module uses this signal to calculate wheel acceleration. If a wheel is about to lock up, the brake fluid pressure at the wheel is modified by the hydraulic control unit based on input commands from the ABS control module.

The system either reduces or maintains the brake line pressure during intervention. The ABS system does not have the ability to apply the brakes.

  • The rapid regulation of the brake fluid pressure during ABS intervention is what causes the brake pedal to pulsate and chatter.
  • 4MATIC, ASD, or ASR systems do not conflict with ABS braking.

4MATIC

4MATIC automatically adds front wheel drive to the normal rear drive mode when road conditions demand it. Depending on the available traction and road conditions, the system operates in one of three power transfer modes: 35:65 front to rear, 50:50 front to rear, and 50:50 front to rear with locked rear differential.

4MATIC models were available from model year 1990 through 1992.



ASR (automatic slip control)

On slippery, adverse road conditions, the ASR system electronically reduces engine power and/or applies the brakes to the driven wheels to maintain the greatest traction possible during acceleration or cornering.

ASR was introduced on gasoline engine cars (except 4MATIC models) as optional equipment from model year 1991. ASR was standard equipment on the 500E.


ASD (automatic locking differential)

  • ASD was introduced on diesel engine cars as an option beginning in 1991. This electrohydraulic controlled rear differential automatically transfers driving power to the rear wheel with more grip. ASD is active up to approximately 19 mph.


Suspension

The E-Class suspension was adapted from the earlier Mercedes-Benz 190 series.

  • Front suspension is a damper-strut system with control arms. The McPherson strut design was not used owing to space restrictions. The spring is mounted separately, inboard of the shock absorber. One resulting benefit of spring separation is the ability to use softer more comfortable spring rates.

In later years a high performance Sportline option was offered that included stiffer, shorter springs, sport shocks, larger diameter sway bars, stiffer rubber bushings and a quick ratio steering box. The Sportline package provides extremely precise handling and weight transfer with minimal body roll.

  • The E-Class rear suspension looks like it belongs on a modern road-racing car. Movement of the rear wheel is controlled by five links that limit travel within a precisely defined arc.

This rear suspension design endows the car with neutral handling, excellent straight ahead tracking, good lateral stability, good anti-dive and anti-squat, as well as braking or acceleration with no rear wheel steering. Seventy different versions of this rear suspension were tried before the factory decided on the final version.


Body Interior

Interior comfort

The steering wheel with SRS airbag includes an electrically adjustable steering column. The total fore/aft adjustment range is 2.36 inches and the column mounted controls move with the wheel. On cars with electric seats with memory, the positions of the steering wheel and the driver’s seat headrest are automatically stored with the seat position.

Electric seat heaters were offered as an option for the front seats, which in most cases came upholstered in leather. On cars with leather seating, the front and rear center armrests and headrests were leather covered as well. For improved rear visibility, the driver could lower the rear headrests using a switch in the center console if the rear seat was not occupied.

Upholstery options (M-B Tex, leather and velour) were available in black, blue, dark green, palomino, cream beige, burgundy and gray. The interior paneling matched the seat color. The dash panel colors were limited to five and the headliner to three. Zebrano (Zebra) wood was used for the trim in the center console for most models. On 8-cylinder models, a burled walnut was used.

  • The base AM/FM radio developed 20 watts per channel into speakers at all four corners with a console mounted fader switch. Radio features also included Dolby noise reduction, adjustable signal search levels, metal tape capacity and a visual tone display. A 100-watt, ten speaker system became available in later years, offered as an option on most models.

The radio unit was wired to the vehicle alarm system, rendering the radio inoperable if removed while the alarm was armed.

End of excerpt

2002 Robert Bentley, Inc. We encourage visitors to link to this page if you’d like to share this information with others. Please do not copy this excerpt to other web sites. It is protected by copyright and represents significant resource investment by Bentley Publishers.