96 AWD Explorer blown differential(s)

[KINGMACK]

I loved my 96 V-8 AWD Explorer until two weeks ago. The front differential exploded and caught fire on I-95 on the way to Orlando, FL at @80 mph. Had it replaced, blew again @ 50 miles later,again at freeway speed. Replaced again, blew again, same story. New shop said the differential was the wrong gear ratio, made sure they had the right one, replaced again. Guess what, freeway speed, spewing smoke and gear oil. Shut it down, towed to Ford garage. They say they hear a little noise, and the seals need replaced, but differential seem fine. I know it will pop as soon as I put 50 highway miles on it.

I had the front tires replaced with all-terrain radials before this trip, and the first problem was @150 mile down the road. An experienced mechanic suggested that the tires may be different sizes, but the Ford garage checked sizes, even measured with a cloth tape.

Any ideas? I am at the end of my rope and wallet!

 

[Robb]

Well, that sucks!!

I don't believe I have ever read anything here, or anywhere else, about front diffs blowing like that.

I have heard rumors, although not here, about Ford often mislabeling the 8.8s. I read the account of one guy that said that he had two explorers, and both of them had actual r&p ratios that didn't match the door code.

Not sure where to even start here, but try this for beginners. First, get under the rear of your truck and look at the metal tag attached to one of the differential cover bolts, record the info on that tag. Then, look at the sticker on your driver's door jamb, and record what the "AXLE" code is. Then tell us all that info, and we can at least tell if your axle code matches your actual diff tag. This is just a stretch that the mechanics are determining your gear ratio by the door sticker, and possibly it is wrong.

 

[Redrig]

Robb, This is kinda of a guess here but wouldnt the transfer case go out if the gears were mismatched?

 

[KINGMACK]

Thanks, I'll give it a try. The mechanic at the second shop actually counted the teeth on the gears to make sure it was right. I wish I knew more, but the first two that were installed were 9 something, and the last one was 8 something, and that was supposed to be the right one. It is at a Ford garage 100 miles from here, so I guess I will forward your response to the mechanic.

Thanks, I am desperate for help.

 

[V8BoatBuilder]

Try running without a front driveshaft. It's perfectly fine, and won't harm anything. It will allow the front diff to spin from the tires, but no power will be applied, and gear ratio will be irrelevant.

Just apply your parking brake, as "park" is rendered useless without the front shaft.

 

[CDW6212R]

Ditto, what he said. Without the front driveshaft, you won't be binding up.

Two different tires on one end seriously makes the tire diameter the most likely answer. It sounds like you have much different types of tires on each end. Different types of tires can easily have a different rolling diameter. You can't measure it without the tire spinning at highway speed. Centrifigal force is probably making two of the tires grow much more than the other two.

I care because I have a 98 AWD Mountaineer with 30.5" tires, and a 30" spare. Good luck,
Don

 

[puddle jumper]

do you think that it may be possible that one or maybe both calipers are putting a slight drag on the rotors and causeing heat build-up that is transferring through to the front diff and causeing your problem ?? maybe the problem was un noticeable untill you got new tires on the front and traveled on the interstate,, but since this only started when you got new tires on the front its hard to say whats going on without looking at it myself ,, let us know if you find out something,, this one has got me thinking

 

[elkhunter]

You could always go back to the original size and see if it is the tires or not.

 

[Robb]

I can't see it being the tires. 4wd drivelines are setup to allow a little bit of slack in ratios. Unless the front and rear tires are marked different sizes, or they are from different manufactures, small differences shouldn't make a difference.

Redrig, yes, you are correct, the tcase chain should go before the ring & pinion bind up that hard................but you never know.

 

[elkhunter]

It was stated that it started after he put new tires on it. If he went back to the old tires at least he would be able to rule them out if it does happen again. Just a suggestion because nothing else was changed before this started happening. JMHO

 

[Cali' Explorer]

I have a question for you. WHen you say you had it replaced, do you mean a whole brand new front pumpkin, or did they just replace the gears?

A friend of mine who is a mechanic has had to replace 2 front ends because the two Bearings that hold the gears in the pumpkin went bad. End result was a smoked Diff, but after replacing all the bearings in the front Pumpkin, everything was good.

He also mentioned that his All Data system mentions this as a common cause on the AWD X's. May be worth checking into (PS, to replace all the Front Pumpkin bearings should be much less $$ than the gearing).

Good luck, and keep us posted.

 

[Jeeps&Fords]

First, DO NOT drive an AWD without the front shaft - it will ruin the differential inside the transfer case. You should have a 3.73 ratio, which is 11 teeth on the pinion, and 41 teeth on the ring. The AWD transfer case should be able to handle a slight difference in tire sizes, and the Transfer Case would be the first thing to go if tire sizes were the problem.

When the diff exploded, what parts were replaced? Was there a diagnosis as to what caused the initial explosion?

 

[Cali' Explorer]

Jeeps & Fords-
Not to be contradictory, but you will not ruin anything by running without the front driveshaft. There is no "Differential" in the Transfer Case. There is a Viscous coupler which is more like a Limited Slip unit, but with how the Transfer Case is built, there is a solid connection between the input to the Transfer Case and the Rear Output of the Transfer Case. The only way to damage the viscous coupler by removing a driveshaft would be if you removed the rear driveshaft and drove around using only the front.

 

[CDW6212R]

Ditto. I drove about 900 miles last year while I had a new front shaft custom made. No problems.
Don

 

[Jeeps&Fords]

You are right - my bad. I have my mind stuck on the old BW 1345 cases that they used in Jeeps (Quadra-trak).