Wolfgang's ML Page: Mercedes M-Class Offroad Mods

Mercedes M-Class Offroad Mods

BFGoodrich All-Terrain T/A 35/12.5 R16.50 on
steel wheel
Clearance increased by 4 inches.

max side slope
The max tilt angle becomes smaller when raising a vehicle. In practise this means a raised ML or with a high roof carrier should probably not exceed 30 degrees. Some passengers pucker already at 20.

max side slope
G-Class 54 percent 27 degrees

M-Class 84 percent 40 degrees

S-Class 100 percent 45 degrees

tires
Tires are the most important change: BFGoodrich, Bridgestone and Pirelli 265/75 R16 raise the ML about 1.5 inches all around. Truck rated tires, marked LT in the table, instead of passenger car tires, can carry more weight, even if deaired, important when off-road, since a larger footprint has more traction on rocks, mud, soft sand etc. This table lists different M-Class off-road tires.

Here are the dimensions with stock tires viewed from the front, side and rear.

The ML does take larger tires. The largest I have tried and mounted are 35" BFGoodrich All-Terrain TA but it turns out they are actually a bit too large to drive around with, due to some minor scrubbing at the replaceable fender liner. The 33" inch BFGoodrich 285/75 R16 are also a good choice. A large payload sags the rear down somewhat which tends to restrict the tire size. That's when HD springs or lift kits (see below) come into play, to compensate for it. On some M-Classes the rear chassis lift point was moved forward by a few inches restricting the tire size.

tire carrier with 33" BFGs

16J x 7.5 H2 wheel
7½J x 16 H2 ET 41

The tires were mounted on an extra set of 7½J x 16 Mercedes-Benz 5 hole OEM take-off wheels, with less wheel offset, ET 41 instead of ET 62 of the stock wheels, which pushes the wheels out by 21 mm on each side compared to stock and increases the track by 42 mm. The clearance increases to 12 inches.
witness 12" clearance on M-Class

8J x 16 ET 62 (OEM)
163 401 02 02

8J x 16 ET 36

8J x 16 ET 40

Otto Fuchs KG makes forged alloy OEM wheels for Mercedes-Benz. For example they supplied the world's first mass produced aluminum wheel to Mercedes in the 1970s, the 6.5J x 14 Barock-Rad, also called 'Bundt wheels' or 'old style alloy'.

99 ML320 with 33" BFG ATs

Off-road specs

approach
angle

departure
angle

breakover
angle

ground
clearance

fording
depth

turning
circle

climbing
slope

'98/99 MLs 28.9° 26.0° 20° 8.4" 20" 35 feet 80 percent

'00/01 MLs 26.0° 26.0° 20° 8.4" 20" 37 feet 80 percent

'02-05 MLs 29.0° 30.0° 20° 8.7" 20" 39 feet 80 percent

ML BFG 35° 32° 27° 12" 23" 36 feet 79 percent

The ML BFG was shod with 33" BFG All-Terrain T/A 285/75 R16s as shown above.
The 12" clearance is shown here.

mechanical diff locks, center, front, rear

Some MLs have lockers and so far tend to be soso performers when running in the same races with stock MLs. One could add self-made lockers. I like the simple beauty of 4ETS and sometimes regard factory lockers as crutches for those who don't like using it. The new M-class has optional center and rear mechanical lockers, or consider the G-wagen.
4ETS test hill

suspension lift, flex, articulation

The front suspension uses torsion bars and can be adjusted in height by 1-2" inches by cranking it up or down. From the rear the ML looks like this.
transmission pic in frame
The M-Class drivetrain is nicely tugged into the rugged box section steel frame and front and rear subframes and is thus well protected from protrusions or rocks on the ground. The rear uses standard coil springs, and Mercedes-Benz does offer several different springs, which may raise the rear as well, and are standard on all MLs factory optioned with the rear tire carrier. This option is only available outside the US, and one may have to order the springs by part number.

Mercedes springs are color coded. Depending on vehicle model, equipment level and spring color code the mechanic selects a rubber spacer at the top. That info including permissable combinations of springs and shock absorbers can be found in the Workshop Information System, Group 32, chassis and suspension. M-Class variable rate rear springs, shocks and part numbers. The M-Class has 200 mm maximum travel at each wheel and can make good use of it due to variable rate springs.

click pic to enlarge
Mercedes M-Class ramp travel index (RTI)
The ML's articulation with 33" BFG All-Terrain tires was measured to be 540 on a 20 degree ramp. It can be increased further by disconnecting the swaybars.
swaybar disconnect front
swaybar disconnect rear
W164 suspension with swaybar disconnect

The Haflinger chassis. Four independantly suspended wheels with coil springs provide exceptional ground clearance and offroad performance. Each half axle has about 10 inches of free movement. Designed by Ed Ledwinka. This suspension is similar to the M-Class.
some Haflinger info

This ML has a 14" inch overall center clearance with an Extrem lift kit which is screw adjustable and can raise the car up to 30 mm (at introduction in 2000 the figure was 45 mm).

The Extrem lift kit was developed with Bilstein and Eibach.

The ORC lift kit raises the ML by 30 to 35 mm (1.2 to 1.4"). The spacers install between the top of the rear springs and the support plate. On the front the ML's torsion bars are cranked up. The ORC lift kit comes with a TÜV approval certificate.

MLOffRoad installed 33" 285/75 R16 Goodyear MTRs and an ORC lift kit.
And lateron 33.9" Super Swamper SSR 285/75 R16s.

picture Magne, Stardust, Land of Ice

The Icelandic lift kit has 15 mm thick plates and screws which are
welded to the top of the rear spring towers.

DaveN007's lifted ML430

10 rubber mounts connect the body to the frame where the Icelandic body lift kit from Starduzt can be installed.

lights
Hella Rallye 4000 HID
Hella Rallye 4000 Euro Beam Lamp
aux electric outlets front and rear are fused with 20A each

bajadesigns: Carrera 4 Light HID System w/ Quick Release

"On demand" light bar with Hella 500s as seen on this ML430 on the Dakar 2004

ORC vs 2002 bumper

bumpers
The bumpers are sturdy ThyssenKrupp Budd steel box frame cross members underneath, but covered with soft and inexpensive plastic bumper covers. Inexpensive compared to many other Mercedes bumpers, and replacement is pretty straight forward in case they are torn or damaged off-road. According to Mercedes these covers are really designed to be easily replaceable. For example 25 slightly used rear bumper skins are currently offered for $158 in the Mercedes parts system in Europe, and the new part 163 880 49 71 is around $300, probably more for 02. One can also install the off-road bumpers from ORC which have more clearance.

bumpers cut for clearance

aux fuel tank, protection plate
The one piece blow-molded fuel tank is made out of a 4.5 mm military spec high density polypropylene plastic tucked into the frame and well protected on the sides. The leading edge of the rear lowered bottom is somewhat exposed and can be protected by a thin sheet of similar high-density polypropylene stuck under the same support straps as the tank, or even better with a plate as shown below and attached to the frame rails.
added May 2002: CAUTION: The metal support straps have sharp edges that might cut into the tank if pulled back by a rock, causing a leak.

Fuel tank protection plate from Extrem, ORC and Vögele

Extrem sells an additional fuel tank with 80 liter capacity which mounts in the space of the spare tire. ORC sells a 60 liter aux tank. For diesel fans, Voegele makes a CDI diesel fuel water separator.

wheel bolts, and solid axles
A wheel broke off the solid axle 4x4 during a recent rallye in Africa, the Dakar 2002 and the vehicle had to be withdrawn and evacuated by the assistance. It did not surprise me since he tried to be as fast as a M-Class. Average speed up to the failure point at km 280 was only about 50 km/h. The independantly sprung M-Class is more durable under these conditions than solid axle vehicles and all 5 MLs continued racing. There are several factors why wheels break off solid axles vehicles: the three times higher unsprung weight triples the g-force experienced by the wheel and axles.

Drive with 30 MPH against a 6 inch curb with an M-Class and a solid axle vehicle. The solid axle takes a 30 g hit and might get damaged, damage the drivetrain, bend the axle, jam the lockers, whereas the M-Class takes only a 10 g hit, one third of the full force on the solid axle vehicle. That's one reason for the M-Class' good durability.

sand boards

Därr sells sand boards. I prefer wood, 2x4 and 4x4 and use it to lift the car out of the sand using a looong lever. It's faster than digging and takes just a few minutes with practise. Also included in their BergeKits, are a shovel, lifter, tow straps.