Low Range 4WD knocking noise [Archive] - Jeep Commander Forums: Jeep Commander Forum

: Low Range 4WD knocking noise


Sandy
01-03-2009, 12:44 AM
I took my less than 10,000m 07 Commander out for a drive in the (sandy) desert last weekend for the first time last weekend. I did not get far.

I was driving on sand tracks, probably less than 5 miles in Low Range when I got a loud knocking sound from under the drivers seat, I think. After lots of to'ing and fro'ing, having switched off LR and the anti-slip, a long (50metres) in reverse stopped the knocking. The next day I tried again, the same thing happened.

It is at the dealership, but I have no faith in them*, so would appreciate some thoughts to steer them in the right direction.

* They just fired four good people.

Ratel
01-03-2009, 03:06 AM
What model Commander do you have Sandy?

Sandy
01-03-2009, 04:17 AM
It is a 4.7 Limited.

I just picked it up from the dealer, apparently the noise is "normal"!

I am sure it has something to do with the electronics that govern either the differential or the antislip. All the dealer did was take it for a test on the road. Are there any other tests or inspections I could ask them to do?

Ahmed
01-03-2009, 06:08 AM
You shouldn't use low range until its necessary. Low range is made to be used temporary !

Sandy
01-04-2009, 01:47 AM
You shouldn't use low range until its necessary. Low range is made to be used temporary !

It was necessary! :)

Anyway I only used it temporarily as the car sounded like it was going to fall apart.

jeep5253
01-04-2009, 12:45 PM
I took my less than 10,000m 07 Commander out for a drive in the (sandy) desert last weekend for the first time last weekend. I did not get far.

I was driving on sand tracks, probably less than 5 miles in Low Range when I got a loud knocking sound from under the drivers seat, I think. After lots of to'ing and fro'ing, having switched off LR and the anti-slip, a long (50metres) in reverse stopped the knocking. The next day I tried again, the same thing happened.

It is at the dealership, but I have no faith in them*, so would appreciate some thoughts to steer them in the right direction.

* They just fired four good people.
I seriously doubt that you you needed to use 4-Low. Ahmed is out in the desert all the time and very rarely has to use the low range. 4-Low is only for very difficult situations such as rock crawling, deep mud, and sand in some cases. You should NOT go faster than 25 mph (40 km/hr) in 4-Low. Using your low range for for a distance of 5 miles is probably not good for the system.

Here are the 4-Low instructions from the Owner's Manual:

4 LOW
Four Wheel Drive Low Range — Low speed 4 wheel
drive. Locks the front and rear driveshafts together.
Forces the front and rear wheels to rotate at the same
speed. Additional traction and maximum pulling power
for loose, slippery road surfaces only. Do not exceed 25
mph (40 km/h).

Shifting Procedures

4 HI to 4 LOW
With the vehicle at speeds of 0 to 3 mph (0 to 5 km/h),
key ON or engine running, shift the transmission into N
(Neutral), and raise the transfer case T-handle. “The 4WD
LOW Indicator Lamp” in the instrument cluster will
begin to flash and remain on solid when the shift is
complete. Release the T-handle.

CUPRA
01-04-2009, 10:06 PM
This thread makes me nervous! I have NEVER used my 4 Lo setting yet, I have been tempted to 'test' it, just from the driveway to the garage, but have never gotten round to it.

Maybe I should leave it that way!

PolarBZ
01-04-2009, 10:11 PM
I periodically put mine in 4LOW just to keep things all functioning nicely. I think you're supposed to do it once a month or so. It gives me a reason to go play!

Yeggster
01-04-2009, 10:45 PM
I use 4 LOW (I have four 4 Wheel Drive vehicles) around town all the time in winter as it provides more traction ... I live down town in a small town Northern Ontario, Canada and the roads are covered with a thick layer of ice and snow all winter though

Sandy
01-05-2009, 02:35 AM
I have also used 4 Low on many vehicles, Land Rover Defenders, Discoverys, Cherokee and Wrangler, in many conditions - here in Oman we have mountains, sand and rocks. I've had trouble before as my Land Rovers were all pretty old.

I have never had what sounded like - remember when you were a kid and you put a piece of cardboard to hit your bicycle spokes to make it sound like a motorbike - well that noise. Not good.

Cupra, I'm nervous too, first time I seriously take my Commander off road and it failed me. I like going to places that are off the beaten track, which are most places here - you can't go into the Empty Quarter with your kids in the back of the car in a car you don't trust.

Ratel
02-02-2009, 09:12 AM
What was the end result then Sandy?

MMOPAR85
02-02-2009, 05:52 PM
I had mine in 4 lo for 3.5 hours this past weekend wheelin' through some pretty steep hills, ruts, and declines! (I even scraped my rear bumper one time and busted some pop rivets!) I've had no problems (thank goodness) but I do know that when the wheels are off the ground, and you give it some gas, they do make a clunking sound, this is because it takes a 1/2 of a turn for the computer to send traction to the wheel that will get the best grip. I've experienced this a few times already while having mine in 4 low it's nothing to worry about. Hope this helps, if your's is a different sound then there's obviously a problem...

kmax
02-03-2009, 12:23 PM
If you have QDII, you may be hearing the clutches in the diffs giving a little when you turn. It's a similar noise to when you're holding the brakes and you let off just a little pressure, you get a groaning noise from the rotors/pads. The clutch packs do the same thing, they're slipping or giving a little. If the computer senses wheelspin, they'll lock up tighter and the noise will go away while you climb an obstacle for example. Both my '06 does it as well as my wife's '08.

As a side note, when you first put it into low range, if the computer doesn't sense any wheelspin, the diffs will not begin to lock up. So you won't have any popping/groaning noise. It's once you lift a wheel or otherwise lose traction somewhere, even a little, the clutches will begin to tighten up and you'll hear the noise. Only when the computer determines traction is good everywhere does it begin the unlocking process which can take a minute or two.

Again, this is only with QDII if I'm correct.

MMOPAR85
02-03-2009, 03:15 PM
Again, this is only with QDII if I'm correct.


Mine does it too though...QT2

kmax
02-03-2009, 03:31 PM
Then I must not be correct! My apologies. I dunno. My diffs make all kinds of noise depending on the pressure being applied to the clutch plates.

08crd
02-13-2009, 08:59 AM
The problem could be due to axle wind up. You should not run in low range with the diff locked if the ground is hard packed, the wheels need to be able to spin slightly to be able to get rid of the built up torque caused by slightly different front and back wheel speeds. That is why you have a centre diff in a constant four wheel drive. Anyway thats my understanding of it, in the old days earth moving equipment that had to be run on the bitumen roads had to stop and reverse every few miles to get rid of the axle wind up because they didn't have a centre diff.

Adondo
02-13-2009, 11:39 AM
First, after owning 4x4’s for three plus decades, this is the first I’ve heard of ‘’ You shouldn't use low range until its necessary. Low range is made to be used temporary !’’

I’ve taken day trips thru the woods, following old logging roads etc. and driven in low range for 60+ miles. It hurts NOTHING. The Commander has a very nice low range ratio actually, at 2.7:1. (Most 4x4’s have 2:1 or less) That does mean the Commander is ‘’pushing it’’ to go much over 25 MPH, so it is ‘rock crawling’ gearing.

It is true that the center differential locks up while in low range. So, to qualify the above statement, it should say to use low range ONLY during OFF-road situations. You need a loose ground surface to eliminate front to rear axle binding. That’s because all 4x4’s have a slightly higher front end ratio than the rear. That stabilizes the rig during off road because the front axle ‘’leads’’ the rear by a small percentage, and that keeps you going straight. On pavement that leads to bad axle binding, tire damage, and worn out ring and pinion gears.

As for sand, you don’t need low range, and it will actually work against you. You need to move copious amounts of sand at times to keep going, and the slow speed high torque of low range will tend to get you stuck faster.

Also while in sand, turn off the traction control. You don’t want a wheel dragging with pulsed braking if the computer senses wheel spin, because most times you NEED that spin in sand. ALWAYS drive as if you have a rotten egg on the gas pedal and if you step down too hard it’ll break. Go EASY on the throttle in sand. Sudden engine power changes will dig you in. During a take off from a stop, go EASY on the gas. You want to glide away from a stop without digging down into it. If it starts spinning a tire let off the gas NOW and try again.

The statement about a wheel spinning a half turn during traction control is incorrect. You can see videos I’ve posted in other threads where my tire is hanging off the ground. The free-air wheel stops after only an 1/8 turn at the most – the computer is very fast. That stopped wheel also pulses in 1/8th or 10th turn increments as the computer checks to see if it has grip yet.

I’m unclear as to your knocking sound. In my XK, traction control sounds more like a tire rubbing against a fender well because the braking pulses are very fast – like a buzzing. Friends have verified from outside the tires are not rubbing, it’s the traction control doing its job. If you have Quadra Drive II, then you have electronic controlled clutch packs in each axle as well as the center differential. In low range, there will be no center clutch pack working – it’s locked solid. It could be the axle clutch packs trying to release axle bind, which might happen in sand because tires are pretty hard to turn in soft sand, which has a lot of drag.

Next time out, try the sand in high range with the transmission down in 2. You will go plenty fast in second range and you need a lot of HP to sustain speed in soft sand.

lekmedm
02-13-2009, 01:22 PM
Adondo, that is one great explanation about 4 wheel drive and off-road driving technique!

Yeggster
02-13-2009, 03:13 PM
The statement about a wheel spinning a half turn during traction control is incorrect .... the computer is very fast.

YES 100% correct .. in fact the Eaton EGerodisc adusts both the torque bias engagement and disengagement times in less than 50 milliseconds

Sandy
02-14-2009, 04:21 AM
Thanks for all the input.

With regards to the high v low discussion - I still think there is a time and a place for everything. Even on my Wrangler which has all sorts of bling and extra fat tires I have had to use low range to get me up particularly steep and soft dunes - and I recently spent a lot of time testing, based on what I had read here. When in a difficult situation I'll try any gear combination to get me out of it!

I took her for another spin on the dunes last weekend. This time the sand was a bit harder, I made sure to switch off the traction control before going onto the soft stuff - I got about 50m before the noise came back. As before, reversing about 20m seems to "unstick" whatever is causing it. When I went forward again, the noise came back. I hate to admit it, but I just "drove through the pain" and the noise stopped as quickly as it had started. I drove for about another hour on the dunes, then through a very rocky dry river bed (we call em wadis here) and then up a very gravelly wet/dry river bed. Not another bad sound. By the way a couple of times when driving through the wet (about 6-8 inches) of gravel I also used low range, that stuff really drags, and the slow constant pull of the LR is reassurring - hope no-one minds.

So I am back where I started. I have a car that may or may not make a really awful noise, that certainly sounds like it could be an out of control computer system. I will try and take it back to the dunes this weekend (your thursday/friday) and have a gentle play to see if I can recreate the condition, and then try and persuade someone from the dealership to come out with me.

Rich

Sandy
03-30-2009, 08:01 AM
Well after a very lengthy process, and I have to say a lot of input from the local dealer, I think we have got to the bottom of the problem - and it may one day affect you too:

The knocking noises were actually caused by the hand brake cables rubbing on the prop shaft and differential when the suspension was fully extended.

The dealer is putting new cables in and re-routing them, and manufacturing new brackets. They are going to raise the issue with Jeep.

I now just need to wait til the parts come in. You should perhaps think about crawling under there and checking the cables, mine were worn through the outer sheathing (sp?).

Oh and today, after its 20,000Km service it has started cutting out while on the move! Back to the drawing board.

Rich