My First Post...Need Help w/ Loud Clunk on Icy Roads!!!

[rpr]

My First Post...Need Help w/ Loud Clunk When Rear Wheels Spin!!!

Great forum you guys have here! This is my first post so please take it easy on me. I did do a search for this topic first, but the threads I saw on "clunks" were a bit different than the problem I have.

I have a 97 XLT (4 Auto, 4 Hi and 4 Lo). When in 4 Auto and starting from a stop (usually), if the rear tires hit a patch of ice there is a very loud clunk (apparently as the tires grab the pavement). The unique aspect of this is that it sounds like it is coming from the rear of the truck, not the front of the truck as most of the existing threads deal with. This is a very loud clunk, and its not just the noise, I can feel it.

It also happened a couple of times while doing 50mph on a highway with fresh fallen snow. That was a bit frightening.

This truck is not under warranty (it's not even paid off). I used to work as a mechanic in my former life about 15 years ago, but I never got into the newer computerized vehicles. Any advice/suggestions on what could be the problem and what I should do to look into this further would be greatly appreciated. Tx.

 

[weebo]

Sorry, I don't have any ideas. My '92 just died tonight and I won't have my '97 til next week or so.

If it was coming from the front then I would imagine that the front differential or transfer case was the culprit.

Randy

 

[TSTONE]

check your u-joints,
if you put your foot on the brake(while standing still) and shift from (r) to (od), and back again, does it make any noise?
todd

 

[ugot5.0ed]

same noise here!!!

Hey-

I have the same damn problem!!!
Check out my post in the tires and suspension section.
When in 4x4 and I hit the brakes i hear a huge clanking noise from the front left axle. You are right i can really feel it. It is scary, the whole car lunges down and to the left. Is it brakes? Is it possible the left caliper is sticking and slowing the axle down faster than the right axle causing opposing speeds in the differential? Does abs have anything to do with it? What the heck is going on? The brakes catch a little harder anyway on the left front, it seems very dangerous in 4x4.

Any one help us!!!!1

joel

 

[rpr]

Tstone:

No unusual sounds at all when shifting between drive and reverse.

I have not had an opportunity to get that familiar with this 4-wheel drive system, but it seems like it is a problem with the power distribution between the rear wheels.

When in 4 Auto, I assume that all the power is sent to one rear wheel up until the point that that that wheel starts to slip. When that one wheel starts to slip, I assume the power is then distributed to the other rear wheel as well as the 2 front wheels. If this is correct, I would assume I have to look at either: 1) the (electrical?) component that regulates the power distribution to the other rear wheel; or 2) the component that physically transfers the torque to the other rear wheel.

My guess would be that it is no. 2; however, if an electrical sensing device is supposed to gradually shift power distribution and instead is malfunctioning and is signalling a an abrupt change straight from 0% load to say 30% load, I suppose that could certainly account for a loud clunk from the strained components of the drive train.

Does any of this make any sense? I'm just not sure how to physically trouble shoot any of this.

 

[TPLYNCH]

There is no shifting of power from one wheel to another, only rear to front and vice versa with the control trac system. Do you have a Limit Slip differential or open differential? You can tell by the codes on the door plaque. If it's a # (41, 42 etc.) you have an open. If it is D#, then you have limited slip. If you have LS, at hi milage (60K+), it should be going bad. Does it make the noise when you hit bumps?? If so, then it could be the rear shocks/sway bar links. Had those fixed twice on my '99 before I hit 36K.

P.S. Welcome to the site!

 

[rpr]

No noise when I hit bumps. It only seems to happen when one of the rear wheels slip. It definitely feels like its drive train related.

I didn't think I had a limited slip differential, but I'm not sure.

Door plaque codes are as follows: "Axle: 45" and "TR: D".

You tell me..is it limited slip??? Tx.

 

[TPLYNCH]

45 correlates to a 3.55:1 open differential.

 

[Sethro]

I think it is your control trac. When the back wheels lose traction, the front wheels kick in. I have the same vehicle and thats what mine does. I have heard it's normal.

 

[hd1]

clunk in driveline

In my recent trip to the Ford dealer I was told that the clunk, vibration was normal due to milage . Every time I come to a full stop and let the clutch out to take off I feel a clunk almost like a reallt bad U-joint. The Ford tech said that it was because the front shaft is always engaged rather its in four wheel or not. The control-trac setup is designed to take torque from wheels that slip to the front axle via a sensor.He also said that when you drive in snow , mud ,whatever letting the auto feature turn the front wheels on there will always be a banging sound. I guess the best thing to do is in crappy wheather flip the switch to 4x4 high!
Hope I was of some help HD1

 

[TPLYNCH]

The noise can also be trace to a slip yoke? that needs to be lubed. Run a search for that and see what you come up with. I know it has been discussed before.....

 

[nevr1zenuf]

Hey there ,
Welcome aboard. I have a 96 eb w/control trac.
the clunk could be your ring and pinion gear.I kept hearing a noise kind of like that especially when i would down shift from 2 to 1st or when going from icy roads to dry pavement with wheels spinning.. I thought it was u-joints but nope to my suprise my ring and pinion were worn like a knuckle on a grinding wheel!!!!OUCH!!!!!
check it out

 

[rpr]

nev: That is actually the type of thing I was thinking based on my symptoms. I can't believe that this clunk/bang is normal on all control tracs.

Sorry for the stupid question, but where and how do I inspect the ring and pinion gear?

 

[01EB5.0]

Originally posted by rpr
nev: That is actually the type of thing I was thinking based on my symptoms. I can't believe that this clunk/bang is normal on all control tracs.

Sorry for the stupid question, but where and how do I inspect the ring and pinion gear?

Depending on how loud this clunk is it might or might not be normal. If you say it's from the rear then I don;t think it can be your control trac system since all that stuff is up front. MIne clunks when the 4X4 auto engauges, but those are just the clutches grabbing and it is considered normal.

 

[DannyD28]

Originally posted by Sethro
I think it is your control trac. When the back wheels lose traction, the front wheels kick in. I have the same vehicle and thats what mine does. I have heard it's normal.

My dads 98 explorer also does this. It is annoying, and its pretty loud, and will jerk you around a bit, but that is usually normal. You may have some kind of a different problem but thats also what I think it is. My 95 doesnt do this because it doesnt have the "auto" type of 4x4. My dealer told me that a lot of people dont like the new type as good as the old 4x4 system. I like the older system cause you can do burnouts with it, but if your 4x4 controltrac clicks in when the wheels start to spin you cant do this too well, or at least I wouldnt think so. just my 2 cents.

 

[01EB5.0]

From an offroaders standpoint the newer 4X4 system is better. You can lock it in both 4X4 high and 4X4 low. the system on the 95 can;t be ocked in 4X4 high so it;s not as good for offroading.

 

[rpr]

The more I think about this, although I do hear a clunk, it's actually the lurch/bucking that concerns me. DannyD28's reference to this as having a tendency to "jerk you around a bit" made me realize that this is a better description of what I am experiencing.

I previously mentioned that this happened a couple of times while doing 50mph on a highway with fresh fallen snow. There wasn't much of a clunk when this happened, but the bucking was very unnerving. Instead of the control trac keeping me on the road, I felt like it was going to buck me off the road.

It seems like a system of this sort should have some type of controlled or phased change of power distribution. What I feel seems to be tantamount to a hole shot (reving up the engine in neutral and then dropping it straight into drive at 4,000rpm). This really may not be too much of an exaggeration if you consider what the control trac will do if your rear wheels happen to lose traction at or near the top end of any gear range. Just doesn't seem right.

 

[01EB5.0]

Originally posted by rpr
The more I think about this, although I do hear a clunk, it's actually the lurch/bucking that concerns me. DannyD28's reference to this as having a tendency to "jerk you around a bit" made me realize that this is a better description of what I am experiencing.

I previously mentioned that this happened a couple of times while doing 50mph on a highway with fresh fallen snow. There wasn't much of a clunk when this happened, but the bucking was very unnerving. Instead of the control trac keeping me on the road, I felt like it was going to buck me off the road.

It seems like a system of this sort should have some type of controlled or phased change of power distribution. What I feel seems to be tantamount to a hole shot (reving up the engine in neutral and then dropping it straight into drive at 4,000rpm). This really may not be too much of an exaggeration if you consider what the control trac will do if your rear wheels happen to lose traction at or near the top end of any gear range. Just doesn't seem right.

Did you have it in the auto setting when this happened or in 4X4 High?

 

[rpr]

It was in Auto.

 

[01EB5.0]

Well, if i understand it correctly the auto is supposed to disable itself at 35 MPH. If you were doing 50 and it bucked there could be a fault in the system. Did the 4X4 lights flash at all?