No power to front wheels when attemting to crawl in low range
02-05-2019, 04:05 PM
#1
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2001 ML 430
No power to front wheels when attemting to crawl in low range
So coming from a lot of real 4x4s I expect to be able at least have one front and one rear wheel engaging while off camber. If I get this car off camber such as proping front end on a railroad tie in the yard, only one rear wheel spins. No pull from the front. If I accelerate hard on a loose surface from a dig, i can see that all 4 tires have pulled. Any ideas?
It's not just in low range. I just attempted to back up to my porch which is up hill on wet ground and same. Rear tires spun but nothing from fronts. I didn't want to hit the gas too hard as to not tear up the yard but this is useless right now.
It's not just in low range. I just attempted to back up to my porch which is up hill on wet ground and same. Rear tires spun but nothing from fronts. I didn't want to hit the gas too hard as to not tear up the yard but this is useless right now.
Last edited by 1k$ML430; 02-05-2019 at 07:35 PM.
02-06-2019, 10:54 AM
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2001 ML 430
02-06-2019, 06:53 PM
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2001 ML 430
02-07-2019, 04:40 AM
#6
MBWorld Fanatic!
I'm not into knowledge of viscous or not but here is info on it.
https://www.awdwiki.com/en/all+wheel...ll_wheel_drive
https://www.awdwiki.com/en/mercedes/ Scroll down to ML.
https://www.awdwiki.com/en/all+wheel...ll_wheel_drive
https://www.awdwiki.com/en/mercedes/ Scroll down to ML.
05-03-2019, 06:55 AM
#7
Lol there is no problem with the front axles otherwise the ML wouldn't move.
Your truck has 3 open differentials and uses 4-ETS to mimic (in a way) having full lockers.
The system engages when the wheel speed of any wheel exceeds approximate 5% of the other wheels.(% changes depending on low range, speed, and vehicle year with the newer years being a bit better+added features) It does this by braking the slipping wheel. It's basically ABS algorithms in reverse.
To "crawl" or dislodge yourself from tricky situations in this truck requires a certain finesse. You have to be very be smooth and consistent with the power delivery. (And yes you will tear up the ground a bit so dont practice on your lawn, lmao)
Basically it works like this...A Wheel begins slipping so the 4-ETS begins to try and slow it down by pulsating the brake to that wheel...if you're not giving it enough power to make the other wheels turn over your obstacle or up the hill, and through the mud, you have to give it more power...but be smooth, dont let off..but dont mash it..just consistent... usually what then happens is another wheel will either begin to slip or the original slipping tire will slip even more (for example if it were in the air) so the brake will try and compensate by ramping up the brake pressure...eventually with enough power and enough controlled slippage you'll force the gripping tires to propel you forward. The system can brake up to 3 tires at a time so theoretically you could get through with only 1 tire with grip.
You have to remember that there is a bit of a delay between when the tire slips, when the system activates, when the torque converter and other wheels begin to load up, when the other wheels begin to grip, and finally propel you forward.
The system is particularly adept at "chugging" through stuff in that as you approach the obstacle you decide on a speed and keep your foot on the gas without letting off and applying more and more throttle if required until you clear the obstacle.
It's an elegant, simple system (that lets you have ABS and easy turning without having to switch off lockers) that requires skill and understanding to use effectively. You can impress your friends by having them "have a go" if they dont understand how it all works lol.
Also be sure to turn off the traction control button when you really need to give it the gas or the system will cut torque from the engine with too much wheel spin.
On the newer, I believe 00 and up ML's theres also an ability to use the brake pedal and the gas at the same time (and a cool feature that wont let you roll backwards in D) which is particularly effective at giving you more rpm, keeping the drivetrain "loaded" and also as a way to preempt a wheel you know is going to spin (lifted or near lifted off the ground) by applying a beneficial braking force to the wheel which is enough for the power to overcome but not spin the errand wheel excessively.
I also believe this helps preload the brakes for higher pressure and instantaneous 4-ets brake actuations (they occur many times a second and are driven by a small motor under the ABS unit).
On the older ML's you can mimic this new feature with the install of a on/off switch on the dual action brake light/brake engagement switch under the dash attached to the brake pedal. Just put it inline with the wires of the switch that do not activate your brake lights) You have to be careful to only activate the switch after you've started the truck, put it in gear and are about to hit the big one or you'll throw codes and lights on the dash and the whole system will shut down, requiring a restart. you'll also lose ABS on the highway and stability control and you will DIE! lol...no really you will. Actually it's better to make this switch a momentary switch you hold when doing two foot braking...for safety. Remember, safety thirds!
Oh another technique I should mention so you dont go getting yourself all stuck right away is the progressive technique. Look at the switches at your disposal as options or tools to throw in once forward motion has been impeded. Once this happens it's best to back out first before you continue on in case you cant back out already....Start in high with traction control on... if you remain stuck you should be able to back out by activating 4 low and reversing...if you still can't...drive the truck forward as much as possible again...now turn off traction control and smoothly try to get out by mashing the gas--but with out digging yourself a giant hole.
Now you're an expert.
Next, reindex your torsion bars, put spacers in the rear, make quick disconnects for your sway bars, and for heavens-sake please break this nasty glass ceiling of no big-tired MLs and mount some big 37x14 wide tires and just cut the living crap out of your wheel wells. It hasn't been done before but it will work with the correct reduced backspacing.
If you then wana go next level get some locking diffs with lower gearing from a few w124 4matics, they require a bit of modifying but you'll figure it out, give yourself a nice 3-4inch body lift maybe, and then mount the supercharged m113k out of AMG 4 or 2 door and push 600hp and oh some 44 inch super swampers.
Then go absolutely bonkers with some prerunner home brew suspension on the front and rear and 14 inches of wheel travel and send it off some big jumps. I'll bring the beer.
Your truck has 3 open differentials and uses 4-ETS to mimic (in a way) having full lockers.
The system engages when the wheel speed of any wheel exceeds approximate 5% of the other wheels.(% changes depending on low range, speed, and vehicle year with the newer years being a bit better+added features) It does this by braking the slipping wheel. It's basically ABS algorithms in reverse.
To "crawl" or dislodge yourself from tricky situations in this truck requires a certain finesse. You have to be very be smooth and consistent with the power delivery. (And yes you will tear up the ground a bit so dont practice on your lawn, lmao)
Basically it works like this...A Wheel begins slipping so the 4-ETS begins to try and slow it down by pulsating the brake to that wheel...if you're not giving it enough power to make the other wheels turn over your obstacle or up the hill, and through the mud, you have to give it more power...but be smooth, dont let off..but dont mash it..just consistent... usually what then happens is another wheel will either begin to slip or the original slipping tire will slip even more (for example if it were in the air) so the brake will try and compensate by ramping up the brake pressure...eventually with enough power and enough controlled slippage you'll force the gripping tires to propel you forward. The system can brake up to 3 tires at a time so theoretically you could get through with only 1 tire with grip.
You have to remember that there is a bit of a delay between when the tire slips, when the system activates, when the torque converter and other wheels begin to load up, when the other wheels begin to grip, and finally propel you forward.
The system is particularly adept at "chugging" through stuff in that as you approach the obstacle you decide on a speed and keep your foot on the gas without letting off and applying more and more throttle if required until you clear the obstacle.
It's an elegant, simple system (that lets you have ABS and easy turning without having to switch off lockers) that requires skill and understanding to use effectively. You can impress your friends by having them "have a go" if they dont understand how it all works lol.
Also be sure to turn off the traction control button when you really need to give it the gas or the system will cut torque from the engine with too much wheel spin.
On the newer, I believe 00 and up ML's theres also an ability to use the brake pedal and the gas at the same time (and a cool feature that wont let you roll backwards in D) which is particularly effective at giving you more rpm, keeping the drivetrain "loaded" and also as a way to preempt a wheel you know is going to spin (lifted or near lifted off the ground) by applying a beneficial braking force to the wheel which is enough for the power to overcome but not spin the errand wheel excessively.
I also believe this helps preload the brakes for higher pressure and instantaneous 4-ets brake actuations (they occur many times a second and are driven by a small motor under the ABS unit).
On the older ML's you can mimic this new feature with the install of a on/off switch on the dual action brake light/brake engagement switch under the dash attached to the brake pedal. Just put it inline with the wires of the switch that do not activate your brake lights) You have to be careful to only activate the switch after you've started the truck, put it in gear and are about to hit the big one or you'll throw codes and lights on the dash and the whole system will shut down, requiring a restart. you'll also lose ABS on the highway and stability control and you will DIE! lol...no really you will. Actually it's better to make this switch a momentary switch you hold when doing two foot braking...for safety. Remember, safety thirds!
Oh another technique I should mention so you dont go getting yourself all stuck right away is the progressive technique. Look at the switches at your disposal as options or tools to throw in once forward motion has been impeded. Once this happens it's best to back out first before you continue on in case you cant back out already....Start in high with traction control on... if you remain stuck you should be able to back out by activating 4 low and reversing...if you still can't...drive the truck forward as much as possible again...now turn off traction control and smoothly try to get out by mashing the gas--but with out digging yourself a giant hole.
Now you're an expert.
Next, reindex your torsion bars, put spacers in the rear, make quick disconnects for your sway bars, and for heavens-sake please break this nasty glass ceiling of no big-tired MLs and mount some big 37x14 wide tires and just cut the living crap out of your wheel wells. It hasn't been done before but it will work with the correct reduced backspacing.
If you then wana go next level get some locking diffs with lower gearing from a few w124 4matics, they require a bit of modifying but you'll figure it out, give yourself a nice 3-4inch body lift maybe, and then mount the supercharged m113k out of AMG 4 or 2 door and push 600hp and oh some 44 inch super swampers.
Then go absolutely bonkers with some prerunner home brew suspension on the front and rear and 14 inches of wheel travel and send it off some big jumps. I'll bring the beer.
Last edited by SpenserM; 05-03-2019 at 07:18 AM.
