Front Differential Question

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

schwallie83

Member
Joined
Nov 24, 2020
Posts
7
Reaction score
0
Location
colorado
I recently purchased a 2000 ford expedition, knowing it needed work.

After driving it for a bit I began to notice a grinding/growling sound from the front end.

This truck is equipped with A4wd, from my research I have learned the transfer case distributes power as needed to the front, based on driving conditions and input from the abs sensors.

My truck does not have a vacuum disconnect for the front differential, so it appears to get all it's power from the transfer case.

I disconnected the 104 fuse for the transfer case motor, and now no more sounds from the front.

I'm assuming this is because all the power is now being sent to the rear, and i am confident there are bad parts in the front differential and it needs to be swapped or rebuilt.

Here is my idea/question:

Is it possible to swap in a front differential with a vacuum switch, wire it somehow into a switch into the cab for engaging the front differential, and then do the brown wire mod for the transfer case with another switch modded to put it in manual AWD or 4wd?
 

ExplorerTom

Full Access Members
Joined
Apr 2, 2015
Posts
2,239
Reaction score
990
Location
Colorado
Reinstall fuse 104.

Do the Brown Wire Mod. Leave the wire cut if you don’t care to retain the a4wd feature. If you do want the feature, install a switch on that cut brown wire.

My 2000 did exactly as you describe. I did the brown wire mod and proceeded to drive it trouble free for 80k miles.
 
OP
OP
S

schwallie83

Member
Joined
Nov 24, 2020
Posts
7
Reaction score
0
Location
colorado
Here is my concern, i know the front diff is bad, and i want to swap it asap.

If engaging the awd feature causes grinding noises, it cant be used at all in the current state.

There is a 3.55 front diff with the vacuum disconnect within driving distance at a reasonable price.

I just want to know if its compatible with my transfer case and if i can install the vacuum switch or an electronic equivalent as a front diff toggle.

If not then i have to roll the dice on a diff sight unseen, shipped and all that hastle.
 

ExplorerTom

Full Access Members
Joined
Apr 2, 2015
Posts
2,239
Reaction score
990
Location
Colorado
Thing is, without the vacuum disconnect on your axle, the front CV joints/diff is turning while driving down the road. You’d hear that noise regardless if fuse 104 was installed or not. No fuse, no noise? Front diff is good.

Taking the fuse out just removes power from the shift motor on the tcase. The noise is caused from you unintentionally driving around in 4wd.

I’d change the fluid in your tcase like yesterday.
 
OP
OP
S

schwallie83

Member
Joined
Nov 24, 2020
Posts
7
Reaction score
0
Location
colorado
Thing is, without the vacuum disconnect on your axle, the front CV joints/diff is turning while driving down the road. You’d hear that noise regardless if fuse 104 was installed or not. No fuse, no noise? Front diff is good.

Taking the fuse out just removes power from the shift motor on the tcase. The noise is caused from you unintentionally driving around in 4wd.

I’d change the fluid in your tcase like yesterday.

yes the front diff and axles are turning true, but no torque is being applied to the gears from the T case, with the fuse out

if the front pinion bearing was specifically the bad one, it would make sense when the awd system sends torque to the front, and the bearing has pressure applied, would the noise appear

i feel if the t case was bad the noise would be ever present

on another note i really think it would be cool to swap in the vacuum disconnect front diff to my truck so i can have on demand 2 wheel drive, awd, or 4wd

i am mainly looking for more clarification on what would be needed for such a conversion
 
OP
OP
S

schwallie83

Member
Joined
Nov 24, 2020
Posts
7
Reaction score
0
Location
colorado
also the t case fluid was changed about 50k miles ago but if you think it's a good idea to change it i will

the previous owner gave me several maintenance records
 

Yupster Dog

Super Moderator
Staff member
Super Moderator
Joined
Dec 7, 2018
Posts
1,322
Reaction score
859
Location
Virginia
i agree with Tom,
But it sounds like you already made your mind up.
If you do it start a thread on it and post pictures.

Good Luck
 
OP
OP
S

schwallie83

Member
Joined
Nov 24, 2020
Posts
7
Reaction score
0
Location
colorado
i agree with Tom,
But it sounds like you already made your mind up.
If you do it start a thread on it and post pictures.

Good Luck

i haven't completely made my mind up, it all depends on what i need to do a proper conversion

but im a bit unclear here

are you guys saying my transfer case is bad? or it's just a side effect of the system design?

if the problem lies in my transfer case that's where i want to start
 

ExplorerTom

Full Access Members
Joined
Apr 2, 2015
Posts
2,239
Reaction score
990
Location
Colorado
are you guys saying my transfer case is bad? or it's just a side effect of the system design?

Like I said, you described exactly what mine was doing shortly after I bought it. I pulled fuse 104 and the noise went completely away. I did the BWM and drove it 80k miles (up to 263k where I sold it- and it’s still driving around the oilfields in TX) without issue. And I took it offroad many times while camping. 4lo was regularly engaged on these trips. 4hi was used on fast washboard (I find it helps to smooth it out).

If you want to swap in a vacuum actuated axle, then party on Wayne.

But I don’t think you need to.
 
Top