So a while back my 95 Eddie Bauer Explorer (tow package equipped) started clunking while driving. The clunking is not only heard, but can be felt, almost as if the vehicle were going over bumps in the road. At the most severe, you can feel the whole thing lurch a little bit, as if power dropped off for an instant.

It happens regardless of transmission selection, except Park obviously, but it happens in Reverse, Drive, or Neutral. It happens at pretty much any speed. It happens with power applied, or coasting, or with engine powered to eliminate engine drag.

The weird part is that it happens only when the selector is in 2WD. It does NOT happen when 4WD or 4WD LOW is selected.

I recently had someone look at it, and his theory was that it was the rear differential, but couldn't really come up with a plausible explanation as to why it would go away in 4WD/4WD LOW. According to Ford, 4WD distributes full power to the rear, and only the power needed to maintain traction to the front, so his theory of "4WD takes the load off the rear" doesn't sit well with me.

Also, I recently replaced the rear rotors, and in so doing I noticed that the right rear wheel has a very slight wobble to it. Nothing significant, I really had to look to see it, but since I was there, I found that the right rear wheel has about a millimeter or so of wobble at the widest point in the sidewall (easiest to measure).

The dealer wants $85 for a diagnosis, and I haven't taken a vehicle to a dealer for diagnosis since they charged $35, so you can imagine how well I took that news.

If it helps any, I believe that my Explorer has a limited slip differential in the rear which came with the tow package.

Any help would be appreciated. Thanks.

Gerry

 

did you disconnect the front driveshaft and drive to see if it's still there ?
Does this noise increase with speed i.e. wheel speed,engine speed? If the slip joint on your driveshaft is dry(no lube) it can bind and release causing a clunking noise, what condition is your cardan joint in rear driveshaft in? If the ball is worn it will rumble?

 

I haven't yet had the chance to disconnect the front driveshaft, but I will do it this week. The rear cardan joint seems to be in good condition, no play in it, although i noticed some odd scrape marks on it that couldn't have happened while rotating, just because of the lack of damage on more exposed area.

The noise does not increase or decrease with engine or wheel speed, exactly. What I mean is: it doesn't go away of you go faster or slower. It does, however, match up with the wheel speed. It's not a regular enough sound that I can definitively say it matches the wheel speed, but it seems to me that when the Explorer is slowing, the clunking also starts to slow proportionately, and if I speed up, the clunking also speeds up. The clunking is not affected by transmission gear, however, and will occur during gear changes, or even in reverse.

Lastly, I had a friend of mine looking at it today. We lifted it up and ran the engine in 2WD mode. He thought it was very abnormal that the front drivetrain remained spinning regardless of the position of the selector. Does this mean that my transfer case is keeping my in 4WD even when 2WD is selected? Oh, and another mechanic who looked at it felt that the rear wheels were unusually tight to turn by hand, and thought that there might be damage to the differential, and he wants to charge me around $600 to deal with it, but I don't trust his vague and nondescriptive explanations.

Thanks,
Gerry

 

If you lightly depress the brake pedal while driving does the noise stop?

 

No, the brakes don't have any effect.

 

Could there be enough drag to keep the front end turning and could you stop it by hand(carefull) If not you have a problem in your t-case.

 

*sigh*

So I put her back up on stands today and tried to see if I could stop the front driveshaft with the Transfer Case in 2WD. I couldn't, and my gloves got pretty hot trying, so it wasn't just a lazy drag. I also caught the front wheels spinning at one point when the transfer case was in 2WD, although it stopped doing that after a minute or so, and didn't do it again.

The other obnoxious thing I noticed was that with the transmission in neutral, and one (rear) wheel being turned by hand, sometimes the other rear wheel would rotate in the opposite direction, and sometimes the same direction. I don't claim to fully understand how the differential works, but I would have thought it should be one way or the other.

Anyone else confused by this?

Thanks,
Gerry

 

The front wheels are ALWAYS powered with 5% power. Its never in a true 2WD mode. That would explain the shaft spinning.

 

Is this a manually shifted trasfer case or electronic. It sounds as if maybe the oil pump in the t-case has failed. My 91 did the same thing in 2H but, in 4H or 4L the chain in the t-case will sling the oil around enough to lubricate things. Ended up with several things wrong in the t-case, planetary teeth missing and severly worn shift forks.

Obviously yours in not disengaging the 4x4. Do your have auto or manual hubs.

The safer way to check the driveshaft in front is with the tranny in park, engine off, and 2H selected, you should be able to turn it with all 4 tires on the ground.

Broncos t-cases are either engaged or not no inbetween. Either all power goes to rear (none to front) in 2H or the torque is split 50/50 front/rear in 4H and 4L.

Btw your rearend is normal. On a open diff rearend the the tire will turn opposite direction the one you are turning, but if the drive shaft happens to turn while doing that the other tire will spin the same direction.

This should be a BW 1356 case or the electronic version of the 1356

 

Thank you both for your help, you have cleared up a lot. In answer to your question, the T-Case is electronically controlled. As far as I know, Ford has issued two TSBs on it for getting stuck in 4L and a chatter on tight turns. Recently, mine has started to chatter a little in tight turns in 4H, but I always thought this was a little normal with 4WD/AWD vehicles.

Also, about five years ago or so, the T-Case started to become kind of loud when going into or out of 4L. It makes a high pitched grinding sound, like a high spinning gear grinding before locking into place. Unfortunately my understanding of the transfer case is almost as bad as my understanding of differentials (which is improving) so I am not sure what to make of that.

Thanks,
Gerry

 

I was going to say automatic, but Ford's Factory Manual has this to say about Explorer Hubs in 1995:

When the 4WD mode is selected, a signal is sent to the generic electronic module (GEM) which energizes an electronic valve located in the right front cowl that draws a vacuum on the disconnect shift motor.

The 4WD locking collar on the transfer case engages the front driveshaft. During this time there will be a 3- to 4-second delay while the inner shaft comes up to speed. The vacuum that is drawn on the disconnect motor moves the shift fork located inside the disconnect housing against a locking collar and slides it between the inner shaft and the constant shaft which locks them together and puts the vehicle into 4WD.

To disengage the transfer case, select the 2WD switch position. This will unlock the transfer case and reverse the direction that the shift motor moves the fork which slides the locking collar from between the inner and constant shafts and disengages them.

Since there are no outer hubs to lock on the Explorer, backing up the vehicle after shifting into 2WD is not necessary. Nor are there any concerns with ratcheting or buzzing noises. Differential motoring torque is not an issue either. Nor does the axle require expensive synthetic lubricant.

I guess the Explorer doesn't actually have wheel hubs, so my problem can't be that, right? (Eh, actually, that would have been easier to deal with. Darn...)

 

Sorry I misread your original post I thought it said Bronco, but it is Explorer in that case I have no idea about the trasfer case or the hub and driveshaft.