KDSS “gotcha”

Ran into a querk with KDSS that got me stuck. I was driving up marked forest road that had a small “creek” running down it (not sure if it was a road going up a pre-existing creek or the creek running down the pre-existing road). I got to a spot where I was going to go up a little 6” step and the right front wheel buried itself in a hole of quicksand Leaving the wheel 3/4 submerged and the weight of the front of the vehicle resting on the skid pan. The other three wheels were on relatively solid (but wet) ground. The KDSS articulated the right front down (as designed) to try and find something solid thereby relieving the left front of traction. My guess is that, had I not had KDSS, more weight would have probably been remaining on the left wheel with traction and it probably would have pulled through without going down to the skid pan. This was my first real off-road foray and still didn’t understand the dos and donts of all the computerized traction controls (as far as I can tell, I was never able to get all 4 wheels pulling at the same time). I may have been able to drive out if I better understood them (never got stuck in my ‘03 Tacoma 4x4 with manual everything and open diffs). Alas, my buddy pulled me out. I later dropped the skid pan and took about 20 pounds of sand and gravel from the pan, undercarriage, wheel, and rotor. Scratched the h*** out of my stock rim. I hope to, in the future, be able to find a sand hill to get “safely” stuck on (with others frequenting the area) to see if I can figure out the traction control.

 

This would have been the perfect opportunity to try crawl control. Or multi terrain select.

The thing is, some hard core off-roaders will remove their sway bars entirely. So, they would be in the same situation.

 

At the time I was trying for something that would work while I was controlling the throttle like A-Trac and/or the rear locker, but neither got all wheels trying to bite at the same time. I never thought about trying Crawl Control to get unstuck. I’ve played with it going up and down rocky trails. I have since learned that Traction Control (normally always on) can be counter productive since its first response is to reduce power to avoid loosing control (like when cornering on wet streets). Next time I go visit my buddy, I might go back and get stuck again just to figure things out.

 

Multi-terrain select uses the brakes to send power to the wheels that have traction. It's basically crawl control but you are controlling the throttle. That's what I would use in that situation.

Crawl control works the same way, but controls the throttle as well. It would have been your best bet for getting out of there.

Are you on the stock tires?

 

Sounds like you got high-centered on the skid. The passenger side of the kdss system is the “fixed” side which does not have the kdss cylinder. Maybe I’m not following exactly what your saying but this can happen to any vehicle.

 

I’ve got Big-O Bigfoot ATs (re-badged Cooper AT3). I think if I had figured out the traction control options and got the remaining 3 wheels pulling, I think it would have pulled out (assuming the high center of the pan in the mud wasn’t the real problem).

Even though the passenger side front is the fixed KDSS point, because there’s a foot or so between the anchor point and the wheel, there is an extra few inches of travel. In my scenario, the driver side KDSS piston had compressed, essentially removing downforce from the left wheel which allowed the right wheel and skid pan to go down further.

I went for the A-Trac thinking it would essentially lock everything together. I was expecting to see some evidence of all wheels digging, but just didn’t see it.

I’m from SoCal where it only rains about one week out of the year. I’m not used to this wet slimy stuff.

This photo is from the next day in a dry gully just to see what would happen. I was curious why it wouldn’t go any farther forward. The left front didn’t show any signs of digging in. I was able to back out without any problem.

 

Diff lock and a-trac together is what may have gotten you out of that.

A-trac does not lock everything together. It uses the computer to sense wheel slip. This will allow the computer to apply brake to the tire that is slipping and send power to the tire with traction to help move you forward.

Also, if the driver front is fully compressed, that is the tire with most traction.

All these fancy tools don’t always work. Sometimes your just stuck. Especially if you are trying bulldoze with your front differential.

 

I should also mention, for those who are unfamiliar with these electronic traction aids, it makes a racket!!!

Often folks who are unfamiliar with the racket it makes just stop and give up because they think things are getting damaged.

A person who is new to all this should find a gravel road or grassy area, you can do this on pavement just don’t turn the steering wheel. Put the vehicle in 4Lo, turn on crawl control to the lowest setting, take foot off brake. The system is going to make a shit load of racket and buck like a bull. It’s normal, the system is using the brakes to try to keep the vehicle at a very slow speed.

If you were to do the same thing on an incline where the system can apply only minimal throttle, it would not buck as bad. The point here is to get used to the system noises. Once you start the crawl control system at the lowest setting, turn the dial to go faster and see how it smooths out. Everyone should play with all this to get used to it.

 

The first time I tried crawl control on the lowest setting on a fairly mild incline. It growled and nosedived like a teenager trying to drive a stick shift for the first time. I took it back to the dealer only to be told it was normal. The lowest setting is pretty much useless unless you’re on a fairly aggressive incline. I think what’s happening is that when the vehicle is idling on a fairly level grade, it’s moving forward faster that Crawl 1 wants it to. Since the computer can’t back off the throttle less than idle, it panics and “touches” the brakes (hence, the nosedive). Now the vehicle is going slower than Crawl 1 wants to, it releases the brakes and idle gets it going too fast and it’s back to “tapping” the brakes again (on infinitum at nauseum). In Crawl 2, however, it thinks the vehicle’s speed at idle on the flats is just fine so it only has to do minor corrections to maintain its sauntering pace. Hence, smoother ride with only the occasional burp from the ABS. As you get up to the higher Crawl settings, it’s more about throttle control than brakes to maintain the desired speed. I know Crawl Control is more than just maintaining speed, but has a lot to do about keeping traction, but this was just a stripped down concept version. I have since used Crawl Control on steep, very rocky roads (a road up a glacial terminal moraine) and it works amazingly well “Look, Ma! No feet needed!”.

 

A couple other things to try in that situation.
1. Try turning your steering wheel left and right while applying some throttle.
2. Try backing up.
3. Try backing up while turning your steering wheel left and right.
4. Try rocking it back & forth, forward and reverse.
5. Try airing down your tires.

Since you were going up hill, easiest way to free yourself would be to go in reverse / back down hill. Gravity is handy for off roading.
Then to get past that area - use momentum (aka speed) - not crazy speed but more speed than what got you stuck.

Mud is a lot like snow in that, none of it is the same.
Airing down your tires might be enough to free you.

If you're on your own - you may need to deploy the traction boards, winch, or dig and stack rocks.
You'll eventually find yourself doing those things with friends.


When I bought my 1st 4wd Nissan Frontier in 2007, I also bought a book on the subject.

$32 Four-Wheeler's Bible: 2nd Edition (Motorbooks Workshop)

https://www.amazon.com/Four-Wheelers-Bible-2nd-Motorbooks-Workshop/dp/0760335303

A non-common sense item taught in the book is to - keep your thumbs outside of the steering wheel. It's possible for the steering wheel to break a thumb off road.

 

ATRAC needs a steady engaged throttle to be effective, otherwise it tends to dial out when you back off the throttle. That’s why it’s good to use crawl control, it keeps the ATRAC on the job and lets the computer keep up the struggle to move forward. Have faith! It works! Better tires would help too.

 

Hey, 4x Old Guy, I’ve been stuck many, many times and often improvised with logs, rocks, old lumber, anything, to get out of a hole. Now that I’m a senior citizen, I decided to live large and bought a set of max trax, which I carry on the roof rack. Too cool! They come in handy in situations like that if all else fails. Now that I carry them, I haven’t used them (yet).

 

I love the scenery! Nice area!

 

These are areas which you solve without thinking about it. Go out and get stuck a lot, and it will get easier and you will have much fun. Keep working it with sensitive feel in different ways, but not so hard that you dig in.
For me, the last thing I want is to turn over throttle control to an algorithm.