Mercedes Benz ML500 Off-Road Build – Project Greta

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The second overland build: Project Greta. The platform: a 2002 Mercedes-Benz ML500, code W163, featuring a smooth purring 5.0-litre V8 snuggly mounted to a body-on-frame chassis belting out a voracious 288 horsepower and full time 4-wheel drive supported by a trick 4-ETS simulated differential lock system. It even included a BorgWarner 2-speed transfer case with a low range gear. Good lawd, what have those Germans designed?

It’s surprising that more people have not modified this vehicle. As of this writing the 1st generation M-class is one of the cheapest, luxury SUVs that you can pick up in the used market. Many will be pleased to know that the price isn’t reflective of the durability of this platform. The drivetrain has proven itself capable of absorbing bucket loads of miles and still running strong. Simple, basic maintenance is all that is required to keep one of these on the road and standard replacement parts are inexpensive.

This thing likes wheel lifts.
This thing likes wheel lifts.

Serious off roaders will frown when they hear that the ML has independent suspension on all four corners. IFS and IRS setups are not prone to allowing much wheel articulation on uneven terrain, but if you’re overlanding you probably aren’t jumping up and down to straight axle swap your Toyota’s IFS. In general, independent suspension is much more comfortable both on and off road compared to straight axles. I would know, my first project was a Jeep Cherokee.

The M-class weighs about as much as a Land Cruiser and costs about as much as a Jeep XJ but with more interior comforts. This model has dark leather interior with heated seats, a Bose sound system, sun roof, front/middle/rear 12v power points, and 80.2 cubic feet of interior cargo space with the seats folded down which means there’s plenty of space for recovery gear, an extra tire or two, jacks, coolers, and firewood. As a comfortable, long distance exploration platform this is starting to make more sense. I think the kids are calling that “over-landing”.

I’ve got big plans for this rig.  This will be a living article which, in the section below, will describe the modifications and upgrades that will turn this into a unique off-road creation.

Current
  • Tires – 35″ BFGoodrich KM3 Mud-Terrain T/A (35×12.5 R17)
    • Issue: Ground clearance and traction were two weaknesses that needed to be addressed. In fact, this entire build was based around these tires and to improve the off-road prowess of the W163 platform. 99% of the M-class vehicles that you see on the road will have summer or all-season, low-profile tires because that’s primarily where this Mercedes product was designed to be. The M-class isn’t as off-road capable from the factory as the G-class, but it can be brought closer to that status with tires.
    • Solution: Fitting the largest tire possible without fender trimming or a body lift made a significant difference. With a few minor suspension tweaks, 35″ tires will fit and are functional. This upgrade improves ground clearance across the board as well as approach and departure angles. The front bumper requires a slight amount of trimming or it can be removed entirely. The rear bumper doesn’t need any trimming, but I decided to cut some of the unnecessary bits for a slight improvement in functionality.
  • Wheel Spacers – 50mm 5×112 hub-centric black anodized aluminum (eBay special)
    • Issue: I wanted to retain the factory 8.5 x 17 Mercedes wheel which have a 52mm (or +2″) positive offset. Because these tires are so much taller and wider they need to be pushed out for proper clearance.
    • Solution: A slightly negative or neutral offset wheel would be ideal, but spacers also work.

Current
OEM rear strut with 1" spacer
OEM rear strut with 1" spacer
  • Front Shocks – Rancho RS9000XL (RS999187) for rear of a 1997 Toyota 4Runner
    • Issue: The factory front shocks only have 2″ of travel. Length is 13″ compressed and 15″ extended. Greater for mall crawling, bad for rock crawling.
    • Solution: The venerable Jon Kucyj discovered that a rear shock for a 97′ 4Runner is a great alternative when cranking up the torsion bar to fit larger tires. Specifically, the Rancho shock he recommends in his video has 7″ of travel, 13.5″ compressed, and 20.5″ extended – plus it’s 9-stage adjustable damping to fit various applications. The torsion bar needed to be re-indexed, cranked up, and upper control arm camber bolts adjusted to straighten the tire out, but it fits 35″ tires with minimal scrubbing on the inner fender liner which can be trimmed or re-molded for clearance.
  • Rear Strut Spacers – 1″ lift high density polyurethane by Infidel Garage
    • Issue: While the front suspension utilizes a torsion bar and shock absorber setup, the rear is an all-in-one strut assembly. So how do you get lift out of such a compact, non-adjustable component?
    • Solution: Spacers! 1″ is the ideal amount to fit 35″ tires with only minor rubbing on the inner fender liner. Ideally, there would be a kit with adjustable coil-overs paired with beefy upper/lower control arms. I haven’t found it, yet.
Rancho RS9000XL - 13.5" compressed / 20.5" decompressed / 7.0" travel
Rancho RS9000XL - 13.5" compressed / 20.5" decompressed / 7.0" travel

Stage 1
  • Custom Prerunner Front Bumper by Infidel Garage
    • Issue:
      • This entire build revolves around fitting 35″ tires. The stock front bumper can be trimmed slightly around the edge closest to wheel well to prevent the front of the tire from rubbing, but I opted to just remove the bumper entirely. Even with the extra lift and ground clearance the stock bumpers hang down much too low which decreases approach and departure angles. (pictures coming soon)
    • Solution:
      • First, a history lesson – the term “prerunner” has its roots in motorsport. It refers to a vehicle that is used to pre-run, or scout, an off-road race course ahead of the actual race to get an understanding of the terrain. These prerunners were often simplified, stripped down versions of stock trucks with a few light modifications to give them the same dimensions and capability of their race counterparts. One of the easier modifications to make to the bumper region is the addition of a simple, tubular design with skid plates that offer protection to critical components in harsh conditions while maintaining a lighter overall weight and maximum clearance. In the late 90s and early 2000s, the non-racing off-road community began adopting these stylistic queues due to their functionality and aggressive aesthetic.
      • I think the prerunner look fits the ML nicely. It’s already a heavy platform and the larger tires are not helping with that, so a minimalist design for the front bumper felt like the finishing touch for the front end without adding a ton of extra sheet metal. I also wanted to be able to attach a winch that was easily accessible but tucked as far back and high up as possible without sacrificing the precious degrees of approach angle that were gained over the stock bumper. This design of bumper also has more options for customization around recovery points and lighting locations.

Stage 1
  • Smittybilt XRC Gen3 12k Comp Series Winch with Synthetic Cable
    • Issue: A winch is one of those tools that you hope you don’t have to use, but it’s very nice to have when you’re good and stuck.
    • Solution: So how do we know what size winch to fit to an M-class? Take the gross vehicle weight rating (GVWR), this is the weight of the vehicle fully loaded with gear and passengers, and multiply it by 1.5. The curb weight of the W163 is 2,093kg, or 4,614lbs, but the gross weight is 2,870kg, or 6,327lbs. Using the gross weight for this equation we get 9,490lbs. In theory, a 10,000lb rated winch would be sufficient, but with larger tires, steel bumpers, and probably a roof top tent from time to time it seemed wise to go to the next level with a 12,000lb Smittybilt winch. To shave off a bit of weight I jumped straight to synthetic line.

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