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Converting AWD to 2WD

mlochala

Active Member
Joined
March 18, 2010
Messages
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City, State
Amory, MS
Year, Model & Trim Level
1998 Mountaineer AWD
I have a 1998 Mercury Mountaineer AWD. I recently changed out all upper control arms, lower ball joints, tie rod ends, CV axles, rotors and brake pads. However, I still have a vibration and a terrible noise which I have discovered is coming from the front driveshaft on the front transaxle. From reading different threads on this site, I'm afraid my front unit has gone bad or at least the viscous coupling is bad.

Financially, I can't afford to swap vehicles or do any more major work to this vehicle right now. Other than the front unit, this is an excellent vehicle with a lot of life left in it.

I was wondering about removing the front unit and then changing the hubs and transmission out for 2WD versions. I'd really rather just have 2WD than AWD. (When I bought this vehicle, it was really the only thing I could find that I liked and could afford.) My questions are this:

1) How difficult is it to remove the front transaxle?

2) Will the hubs or knuckle assembly from a similar 2WD version interchange with the AWD control arms?

3) What transmission would I need to be looking for from a 2WD to replace it with?

4) What else is lurking that I don't know about that would also need to be changed?
 



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You could rebuild your t-case for a couple hundred bucks if you do your own wrenching.
 






Financially, I can't afford to swap vehicles or do any more major work to this vehicle right now. Other than the front unit, this is an excellent vehicle with a lot of life left in it.

Fix the issue at hand and you'll have a nice vehicle.

I was wondering about removing the front unit and then changing the hubs and transmission out for 2WD versions. I'd really rather just have 2WD than AWD. (When I bought this vehicle, it was really the only thing I could find that I liked and could afford.) My questions are this:

1) How difficult is it to remove the front transaxle?

2) Will the hubs or knuckle assembly from a similar 2WD version interchange with the AWD control arms?

3) What transmission would I need to be looking for from a 2WD to replace it with?

4) What else is lurking that I don't know about that would also need to be changed?

That's probably going to cost you more then the repair of your problem.
Financially, I can't afford to swap vehicles or do any more major work
 






I am assuming you have the V8 AWD version with the 4404 transfer case.

You can make an AWD GenII X/Mountaineer rear wheel drive by simply removing the front drive shaft. You'll get a lot of people telling you not to becuase it will "creep" in park, which MAY be true. If the transfer case is in good shape, running without the front drive shaft will cause the viscous coupler to overheat and sieze up. However if the viscous coupler in the transfer case is indeed siezed then it won't creep in park, and you can't kill what's already dead.

the AWD system uses a viscous coupler to divide power between the front and rear drive shafts, there is not a mechanical link. The viscous coupler can fail one of two ways, either it siezes up and effectively creates a mechanical link (similar to running a 4x4 vehicle in 4Hi all the time, this is what destroys the weak little front differential). The other option is it fails completely and no longer drives the front shaft, in which case you effectively already have a 2wd.

If you're just looking to isolate/ confirm the problem is the front diff/ transfer case pull out the front driveshaft and go for a test ride. If this fixes your problem, you can test to see if your viscous coupling is bad before you reinstall the front drive shaft by parking on a hill. Put the truck in Park, put a brick, rock, whatever about a foot or so downhill of the wheels to stop it should it creep, and let it sit for a few hours. If its moved (if it moves at all, it will be at a super slow, impossible to see creeping pace) then your viscous is still good. Either put the front driveshaft back in and try to scrounge up a junkyard front diff from a 4x4 verson, they're cheap and easy to get, and since you already know how to tear the front end apart it's only a few more bolts to have the front differential out. The other option is leave the front driveshaft out, accept that it's going to ruin the viscous coupler and know that you'll have to use the E-brake every time you park to ensure it doesn't creep. Free-spinning the front diff won't hurt it, and the only thing left that might be bad up there are the wheel bearings, in which case you're going to be unhappy because they're about $150 apiece.

I have a 97 V8 AWD Explorer with 233,000 miles on it that we've been running for a year now without the front drive shaft. The viscous coupling siezed up, the Mrs didn't notice it was super hard to turn and that the truck was acting funny, so she drove it long enough to seriously damage the front differential. I got in it one day and it wouldn't turn out of the driveway without throttle input things were so bound up. I looked into rebuilding the 4404 transfer case, the visous coupler alone is about $500, plus around another $100 or so for the gaskets and bearings. Then you get the joy of doing at minimum a whole weekend of wrenching, and you still have to replace the roasted front diff which will cost you around $100 or so from the junkyard.

Just my two cents.
 






You can make an AWD GenII X/Mountaineer rear wheel drive by simply removing the front drive shaft. You'll get a lot of people telling you not to becuase it will "creep" in park, which MAY be true. If the transfer case is in good shape, running without the front drive shaft will cause the viscous coupler to overheat and sieze up. However if the viscous coupler in the transfer case is indeed siezed then it won't creep in park, and you can't kill what's already dead.

It will still creep in park. I know this because my 97 is sitting in my driveway with a seized VC and 2 cinderblocks behind the back wheels so it doesn't creep down my driveway.
 






Thank you for all the responses! I appreciate your advice and time.

For now, I'm going to remove the front shaft and see what happens. But, I would still like to know, are 2WD front knuckles or hubs compatible with the AWD suspension or knuckles?

If just removing the front shaft will solve the problem for now (I can't rebuild the transaxle right now), then I would at least like to see about changing out the front hubs or knuckle assembly so that I could remove the transaxle and the CV axles.

What are your thoughts on changing the front knuckles (or hubs) and removing the transaxle completely?
 






You know, If you're really trying to make a proper 2wd, I don't see why you need to switch out the hubs or buy any new front end parts. The way the front end on these things are built the hub and wheel bearing is all one unit that the CV shafts slide into and drive. The front differential doesn't hold anything in place, nor do the CV shafts. You should be able to remove all of that stuff. You'll still have the transfer case hanging out back there, but I suppose you should be able to swap the tailshaft for a 2wd F150 that has the 4R70W transmission in it, have a driveshaft custom built and away you could go? You may run into trouble figuring out your speedometer though. I'm not sure on the 98+ but through 97 there's two hall effect speed sensors, one in the front output of the transfer case, and one on the rear output that are used to drive the speedometer, and give feedback to the electronically controlled automatic transmission. Also, I don't know if they made V8 2wd Explorers so, you may have to modify or fabricate a transmissoin crossmember as well. I'm sure it's all possible to work out, I just can't offer feedback there.

Seems like a lot of un-necessary work though. If your truck is like mine and worth less than the cost of repairing or modifying it, why mess with it?

As for a sized viscous that still creeps. Sounds fishy. There are threads on here you can see in detail how the 4404 transfer case works. If it's creeping in park with no front shaft that means the fluid differential in the transfer case is indeed still allowing at least some "differential" speed of rotation in the front and rear drive shafts, so it can't be truly siezed. You'll know when it's gone bad, you won't be able to turn the truck in and out of parking spaces without a lot of throttle input and when taking tighter corners on the road you'll chirp the tires, not to mention the front diff will get ground up so bad the whine will deafen you.
 






You know, If you're really trying to make a proper 2wd, I don't see why you need to switch out the hubs or buy any new front end parts. The way the front end on these things are built the hub and wheel bearing is all one unit that the CV shafts slide into and drive. The front differential doesn't hold anything in place, nor do the CV shafts. You should be able to remove all of that stuff...

With no CV shaft in place, the interior of the hub is exposed. I would assume this would lead to premature bearing failure.

I am contemplating cutting the splines off the old CV axles and welding a large washer to the back end and then reinstalling them in the hubs so that the hub interiors will not be exposed. That way, I can completely remove the CV axles and the front differential.

...You'll know when it's gone bad, you won't be able to turn the truck in and out of parking spaces without a lot of throttle input and when taking tighter corners on the road you'll chirp the tires, not to mention the front diff will get ground up so bad the whine will deafen you.

Mine was doing that exactly. I just got finished removing the front shaft and on the first test drive, I was amazed at how much more loose the vehicle felt. When I backed it up to turn around, the difference was very noticeable. I didn't realize how bad it had gotten, though I will admit that at times it felt like we had left the parking brake on.

By the way, this is primarily my wife's vehicle. I only drive it on Sundays when we all go church or if we all go somewhere together.

Right now I have it parked in my driveway to see how bad the creep will be. Our driveway has quite a grade to it so if this will be a problem, I should know pretty quick.

One more question, is the viscous coupler located in the front differential/transaxle or in the transfer case situated between the transmission and rear drive shaft?
 






Ahh, good call on chopping the splines off the 1/2 shafts to "plug the hole" in the hub/bearing. I believe the control arms/ hubs/ everything are different on the 2wd versions, so that would be a lot of work to convert.

The viscous coupling is in the transfer case. The front axle (differential) is the same in all the 97-01 explorers and only slightly different for 95 and 96 regardless of AWD or 4x4, however the 4x4 front axle won't have had torque put through it for 100% of its mileage like the AWD versions. Do a search in the forums for the 4404 transfer case, there are some great writeups on rebuilding one that will give you a great sense of how it works, and why yours is acting up should you decide when your cash flow is better that you want to fix it properly.

If yours is that siezed I'll bet it won't creep. Mine doesn't and my driveway is also a pretty solid grade. I was basically in your same shoes. The Mrs drives the "big" explorer (she's not fond of the 5 speed in the other one) and as the viscous got worse and worse over time slowly she didn't notice the change. I almost never drive it, and we generally use my sport for trips together since hers has such high mileage (still on the original transmission at over 230K) I can't remember why I ended up driving it actually, but pulled the front shaft the same day and haven't looked back since. I had to put some snow tires on it this winter to compensate for the loss of the AWD and the fact that the factory limited slip still works great on ice. Not the most elegant solution, but it's allowing us to enjoy what little life is left in an otherwise fantastic truck.
 






The verdict is in and our Mounty is a certified creeper. I guess that means I'll have to fix the parking brake now...

I was just curious, but has anyone else ever done what I am thinking of doing and plugged the hub bearing with a modified half shaft spline?
 






You could rebuild your t-case for a couple hundred bucks if you do your own wrenching.

couple hundred? well, couple hundred for the VC alone. Which wouldn't be a true rebuild. I paid around $300 for my VC, and I believe I've seen some online for around $200. Add in another ~$70 or so for the bearing and seal kit.

The verdict is in and our Mounty is a certified creeper. I guess that means I'll have to fix the parking brake now...

I was just curious, but has anyone else ever done what I am thinking of doing and plugged the hub bearing with a modified half shaft spline?

it has, but I don't have a link to the post or anything. But I remember reading at least one thread where the cv blew up while wheeling, so it was torn apart and the stub shaft left through the hub. Although I don't believe it was a long-term solution.

as for converting to 2WD; not cheap. Nobody really knows exactly what will happen to the VC if the vehicle is driven long-term without a front driveshaft. There are speculations/guesses, but I don't believe any of that has been proven.

For example, I probably put around 3k+ miles on mine without a front shaft; did not appear to cause any adverse affects.

Otherwise you would need to swap the transmission with a 2WD unit to get rid of the t-case.
 






the CVs can be gutted so that just the stub that goes through the hub is left, no cutting
 






couple hundred? well, couple hundred for the VC alone. Which wouldn't be a true rebuild. I paid around $300 for my VC, and I believe I've seen some online for around $200. Add in another ~$70 or so for the bearing and seal kit.

when I talk automotive and say a couple hundred, it usually means 400-500$.

And honestly that aint bad for essentially a new t-case.
 






when I talk automotive and say a couple hundred, it usually means 400-500$.

And honestly that aint bad for essentially a new t-case.

when people say "couple" that means, 99.9% of the time to probably 99% of the population, to mean 2 or "around 2"

more than 2 and you get into a "few"
 






You'll know when it's gone bad, you won't be able to turn the truck in and out of parking spaces without a lot of throttle input and when taking tighter corners on the road you'll chirp the tires, not to mention the front diff will get ground up so bad the whine will deafen you.

I'm getting binding on tight turns, but no chirping. The last time i parallel parked it felt like the parking brake was on. The X runs great otherwise, with no noises or vibrations up to 100 mph, thats my limit :)
I picked up a used case with 89k miles to swap out, and keep the original as a spare to rebuild. Is there any way to bench test the viscous coupling?
I plan on opening up the case and doing a visual inspection too.
What should be replaced while i have it open?
 






I'm getting binding on tight turns, but no chirping. The last time i parallel parked it felt like the parking brake was on. The X runs great otherwise, with no noises or vibrations up to 100 mph, thats my limit :)
I picked up a used case with 89k miles to swap out, and keep the original as a spare to rebuild. Is there any way to bench test the viscous coupling?
I plan on opening up the case and doing a visual inspection too.
What should be replaced while i have it open?

there is no documented bench test documented for BW4404. I have seen one or two floating around for Chevy, Jeep, and even some old VW Vans that had AWD. I believe most of the "bench tests" required the case to still be installed in the vehicle, though.

As for what to replace? Might as well get a bearing and seal kit for around $80 or so, may end up wanting to get a new chain (FYI, there may be 2 different chains listed, with the same length, teeth, pitch, etc, but they are actually a different width by 1 link).
 






I have another question regarding this, basically an "out of curiousity" type of question. I noticed where the spline end of the CV axle inserts into the back of the hub, there is no seal of any kind that sits flush between the CV axle and the hub. It appears there is a little exposure to the backside of the hub just behind the spline.

Is this normal or is there some kind of seal that is supposed to be there? There wasn't an existing one when I pulled the originals off. Again, I'm just curious.
 












from my experience, new CV axles from Napa have a rubber "seal" on the shaft, to sit between the CV bowl and hub/knuckle. The remanufactured shafts from Napa or Carquest do not have this rubber dust seal.

Look at the 9th picture in that thread; it's a picture of the new and old shafts. You can see the old shaft has that seal, the new one does not. (Although yes, the picture is of an old pass side and new dri side)
 



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