I’ve had the great opportunity to chat a little with Wolfgang Henke, legendary individual and Author of Wolfgang’s ML page (
http://www.whnet.com/4x4). I have invited him to join our discussion, if he has time and interest. Wolfgang shared with me some minimal things that can be done to raise the ML. First, he says the largest safest wheels he uses are 33” BFGs (285/70 R16) and not 35" tires as stated above. using the 33" BFGs will raise the ML about 2.1 inches over the stock 29” tires. Second is to change torsion bar settings which can be elevated up to 1 to 2 inches (
http://www.4x4abc.com/ML320/ml320_torsion.html). This would be done to reduce or eliminate any tire rubbing plus to provide more clearance. He advises caution as severe changes to the torsion bars can result in near term damage to the front driveline. In addition, one should have the front end aligned after raising the torsion bars. Wolfgang said he did not and his ML showed no tire/driveline damage as a consequence.
At Gary Robert’s site (
http://www.dragnet.com.au/~groberts), he says one can also install heavy duty (and somewhat longer) rear coil springs. In fact, if you get your ML with the rear tire carrier this is a stock addition. (
http://www.dragnet.com.au/~groberts/mlsprings.html ) WRT rear springs, Wolfgang suggest:
”Mercedes springs can be a very tricky business, and they are color coded in many models, including the ML. One has to make sure that a new set of rear springs fits together correctly with the shock absorber and the rubber mounting pads, which in some other models than the ML are used to even out or adjust spring ride height. That's something a good Mercedes mechanic with access to the online system, should be able to check out for you, in Workshop Information Group 32, chassis and suspension.”
A torsion bar adjustment, and different coil springs are both within the area of stock, as there is no non-factory items applied. Oversized tires are literally a bolt-on item but you may want to get different rims to change the offset or just to not risk your factory rims. In addition, Wolfgang claims that the bumpers on at least the ’98 and ’99 models are intended to be inexpensive and replaceable. He should know as he’s replaced 3 sets of them so far!
These minor changes will raise the ML to about 12” of clearance, minimum. As to trail rating, according to this site (
http://skidplate4x4.tripod.com/Trail_Ratings.html) these changes would permit the ML to be comfortable on an 8 rated trail (on the 1-10 system) and I could only guess a 3+ or 4 on the comparatively imprecise 1-4+ system)
As you raise a vehicle, there is an increase in tippiness. The stock ML is good (as illustrated above) for 40 degree lateral angles. Wolfgang calculates that the maximum safe lateral angle decreases by about 1 degree for every 2 inches of increased clearance. Even so, he says that by raising the vehicle use a 30 degree lateral as a working maximum even though it should be good for up to 35 degrees. Good idea as when you are way over, even a fairly small rock can gain you an extra 5 degrees angle in a heartbeat!
Koly suggested that by changing the tire sizes you could adversely affect the ML’s traction control system. Actually, by putting in larger tires you will reduce the maximum torque just a little, but that’s about it. As the ML uses computer controlled algorithms to determine slippage and not just simple linier if-then “rules” it wouldn’t really care what size the tires are. Remember this is a fast acting, constantly monitoring intelligent system incorporating 4wd slip control (4ETS+), 4wd yaw control (ESP), 4wd brake assist (BAS), and, of course, 4th generation anti-lock brakes (ABS). Itself, 4ETS+ constantly evaluates (don’t know the interval) for differences in wheel spin while it’s cyber brother, ESP concurrently checks for yaw. If spin is found the system will, of course use the ABS system to brake the wheel(s) spinning, but briefly, and then retest for spin and re-lock if necessary. The 4ETS+ and ESP systems are biased to slow the vehicle down in adverse conditions. If you have 3 wheels with no traction the system will send power to the one that isn’t spinning, but along with re-assessing the other wheels for spin will slow the auto down anyway. Even so, if you want to put it in 2nd and use the 2 pedal technique, you get a 0 slip system that actually is significantly enhanced even beyond what lockers do!
To put the issue in empirical terms, if you were on ice, and the system detected sliding, it would slow you to a stop if necessary to insure safety. As an example, shortly after I got my ML I took it for some test figure 8 in the huge lower parking lot at Crystal on a snowy day. Unless you carry a lot of speed into a turn the 4ETS/ESP system will simply not let the car slide perceptibly, even if you floor the gas pedal, and on a corner ESP will slow the car. If fact, this desire to bring the vehicle to a stop is the well noted problem with ESP! The solution for this type of problem is to turn off ESP. This permits some wheel spin, but does not defeat 4ETS+. When I did more figure 8s with ESP off, I could pretty easily make the ML do pirouettes. It didn’t take much to convince me of how much ESP enhances traction control!
Questions?
Regards
