using brakes when in 4 low grinds like gears ?

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donberry

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2003 KJ w/ auto transmission, new to the 4wd aspects of it, at the moment is 100% stock.
Took it out and got into into some heavy red clay mud like you find in Tenn. I was in 4 hi and got stuck, just sat there spinning. Tried to rock it out by going forward as far as it would go , brake, reverse as far as it would go, brake, etc......
Still stuck so I put it in 4 low
Did the same rocking, but in 4 low, when I pushed in the brakes it would make a pretty serious grinding noise on the front brakes - it was pretty much exactly like I was changing gears with a manual transmission without using the clutch ?
The pedal would sort of pulse, then it was like it "caught" and slipped into gear -yes, I am still talking about the brakes - seemed really weird to me.

While I admit I no basically nothing about BLD, which is active in 4 low, from what I have read I was under the impression all it is really doing is applying pressure to the wheel that is turning - so there aren't any gears involved - still just pushing the pads against the rotors if I am not mistaken ( which I obviously must be because this was definitely gears, not a grinding noise from pads on a rotor)

I obviously have no idea what was happening and was wondering if anyone would happen to know what the heck was going on ?

I was actually kind of surprised I got stuck in the 1st place. Mud wasn't that deep and I figured I would pop right out when I 1st started rocking it. Then when the brakes started grinding like that, I must admit I got a little worried. Of course idiot that I am, I had my window down when I 1st started trying to spin out......fortunately there's not too much mud inside and it pretty much stayed on the door......so as you can see, I am obviously not that bright to begin with.

Plan was to start putting together the kj backbone/winch combo and frankenlift/OME lift after Xmas, but I obviously need to figure this out 1st. I am no expert by any means but I have changed a bunch of brake pads, master cylinders and lines, and rotors over the years on my own cars and thought I had a pretty good grasp on how the brake system worked but I can honestly say that I do not have the 1st clue to where gears become involved when dealing with brakes.....and there is no doubt in my mind that what I was feeling in the pedal and hearing was gears grinding......

Any info greatly appreciated.
 

TwoBobsKJ

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Welcome to the KJ world! (welcome)

My guess is that 4LO didn't engage properly and what you were hearing was the transfer case gears. In order to shift into 4LO the Jeep should be moving very slowly (5mph or less) and the ****** in neutral. Then shift the transfer case into 4LO. Since you were sitting in the mud and not moving, then shifted the handle to 4LO, the gears in the T-case didn't get a chance to engage - hence the grinding noises. I'm not exactly sure why it only made the sound when you hit the brakes, but that's my theory and I'm sticking to it :)

Best thing to do when getting into mud is to stay in 4HI in my opinion. It's kinda like driving in snow (which we get to do a lot here in Northeast Ohio.) Lower gears provide more torque, making it easier for the tires to break traction on slippery surfaces like snow and mud. Higher gears have less torque so a little more difficult to lose any traction that might be there.

I have family in Knoxville and I've had the pleasure to hit some logging trails in the area and that red clay is more slippery than snot, so don't feel bad you got stuck. Plus street tires aren't doing you any favors in that stuff :smoke2:

Bob
 

donberry

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it definitely only happened when I pushed on the brake pedal. When I went forward the 1st time in 4L, I figured it wasn't in gear right, but still did not understand why I could literally feel it thru the brake pedal and only heard it when I pushed in the brake. So, as all i could think of was not being in gear right (tho not understanding why it was a brake issue), I put it in park, shut off the engine, put it back in regular mode and shifted it back in 4 low, then started the engine back up.
I could be mistaken, but I believe the manual stated that if you hit neutral when trying to go into 4L, shutting the engine off is what you are supposed to do. Since I was stuck and not really able to go 3-5 mph, I turned off the engine and did that.

It was sure strange as heck to me, but it only happened when I braked and it really was like shifting a manual without hitting the clutch, only it was thru the brake pedal.........some how, some way, when I was hitting the pedal, some gears some where in the front of the jeep were affected.......

Just off the top of my head and being as ignorant as possible, could it possibly be the ESC did not disengage as it is supposed to and not having a clue why, some how that was affecting something......

Tomorrow, on dry land where I am not concerned about being stuck, I am going to try and see if I can replicate it.

Red mud - the tires on mine are the dual highway/off road tires - but yes, that red clay can be slick as heck.
 

TwoBobsKJ

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To shift into 4LO you definitely want the Jeep to be moving, ****** in neutral. There will be minor grinding when you do that but even the manual says to expect it. Turning the engine off will have no effect.

Your KJ does not have ESC and I don't believe the '03's even have ABS though I could be mistaken. My '03 doesn't have ABS and I'm very thankful for that. I don't think ESC was available until the '05 model year but others on here will chime in to correct me.

When you test out shifting into 4LO be sure you do not turn the wheel at all nor drive for any length of time if you do so on a high-traction surface or you'll damage the transfer case. Same goes for when you're in 4HI (Part Time) as it will create binding in the driveline and you'll hear/feel some nasty bangs. You'll know it when it happens :icon_eek:

Best to try out 4HI and 4LO on loose gravel or mud. If you have Full Time 4WD you can drive your Liberty on any surface at any time (drive it "full time") in 4WD without worrying about driveline binding.

EDIT: What transfer case do you have? If you have 4 positions on the t-case shift handle you have the Part Time case. If you have 5 positions you have the Full Tim transfer case.

Bob
 

donberry

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1st - I know I am about as ignorant as one can be when it comes to this.

As far as shifting it into 4LO, I read thru the owner's manual (it is for a 2004 tho I would guess everything should be the same) when I decided to keep it for me as I had barely even ridden in it, let alone used the 4wd, and it says that if you pause while going from 4HI to 4LO, you may have to shut off the engine to get it in gear. As I wasn't really moving, is why I shut if off - fwiw, it did go right in gear with it in Park and the engine off)

I would guess I have the part time transfer case. On the shift handle I have 2wd, 4HI, N, 4LO

When I said test it on dry pavement, I wouldn't really have been driving it anywhere except a couple of yards or so - mainly I just want to put it in 4LO and hit the brakes.

Thinking about it though, the one thing that I could not replicate would be the tires were spinning pretty good. So just basically creeping, it may not do the same thing it did. I think I'll pull it into my field and try it and if it does not do it, I might hit some mud again.

I totally understand and get where people would think it wasn't in gear, wasn't in gear right etc, but what was imo so really strange was it only did it when I hit the brakes.
Now in 4LO, I "gunned" it some to go forward as far as I could, which was maybe a foot. When I reached the max forward position, I applied the brake to stop it there to switch to reverse to repeat the process going backwards - rocking it out.
Going forward or backwards that foot or so, it never made a sound. I sat there a few times with the wheels spinning pretty fast, trying to "gun" her out, waiting to see if it would "catch" and go......it never made a weird sound.

It only did it when I hit the brakes and I could hear it in the front (sounded to me like it was actually coming from the transfer case, or at least that area, and I could feel it in the brake pedal. If you could imagine a manual shift engine except instead of having a hand shifter, the shifter was the brake pedal. All was silent (except for the sound of spinning wheel and mud hitting the car) until I braked - then it made a pretty serious sounding gear grinding sound and I was afraid to push the brake pedal all of the way down. As the wheels slowed down from spinning, it was like it would "catch the gears" and the brake would then return to normal.........I know it sounds strange as heck.
I was actually a tad worried it was something common and would find out it was something I should have known about........but apparently not.
As there are zero gears in the brake system, I do not know how, I do not know why and I do not even see how it is possible, especially as I do not know anything about computer assisted braking, but it sure seemed tio me at the time like some how the brake was mated to the transfer case.....,.

The very first thing I thought of, once I got out, was I had better figure out what the heck was going on and ask about it here as it sure seemed serious at the time and made zero sense to me.

Worse comes to worse, i am going back to the mud as I really need to see if I can replicate that. Hopefully I can't
 
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donberry

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searching the internet, hard to find anything because no matter how I phrase it everything is always about things like grinding when shifting etc....

I did find this post tho, which pretty much sounds like what was going on with me, only mine was only in 4LO
i have 05 f150. just needed the 4wd for the first time today and when i hit the brakes it would grind and you can feel it grinding in the pedal. it only does it in 4wd.
answers were mainly disbelief, thinking he must have mis-phrased what he meant to say etc, but then one guy gave this reply....does not apply to the KJ as far as locking hubs, but maybe something along these lines ? I think it is a very safe bet that this KJ has rarely, if ever, been in 4LO. Bought it from a couple where it was the wife's car and they said it had never been off road (could have lied of course) and I know my wife has never touched that shifter, probably has no idea what it even was. I only mention this because of this reply
sounds like an internal locking hub issue to me,if it has auto locking hubs and has never bin used it builds up gunk and dirt and may need to be pulled apart and cleaned up, what happens is the dirt stops and old greese clogs the splines in the hub and will not let them be fully engaged so when you hit the brakes the axels continues to spin at a higher speed as the hub slows down
 

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