Which gear ratio? AWD front differential swap. | Ford Explorer Forums - Serious Explorations

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Which gear ratio? AWD front differential swap.

sidneyhop

Well-Known Member
Joined
January 21, 2008
Messages
195
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City, State
Orlando, Fl
Year, Model & Trim Level
2000 AWD Limited
Is there an easy way to determine what the gear ratio is?

Issue: I heard an odd rattling sound (sounded like a stick got stuck underneath and was dragging along the pavement intermittently). It was random and lasted only a few miles. Now theres a low growling noise with a vibration that changes with how fast Im moving. It has no relation to engine rpms.

I suspect its the front differential as thats the approx location all the sounds came from (best I could tell while driving). I want to pick up a used one and assume the gear ratio needs to match the rear? Is this accurate?

Thanks for any advice on all of this.
 



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There's a sticker on the driver's door jam that will have the axle code printed on it. For example - D4 = 3:73 ratio, limited slip rear differential. The front diff will be the same ratio but not limited slip. There should also be a tag on one of the diff cover bolts, though sometimes they're missing.

FORD EXPLORER/Mercury Mountaineer

43 Open 3200 3.08
41 Open 3200 3.27
42 Open 4.10
46 Open 3.73
45 Open 3200 3.55
D4 Limited Slip 3200 3.73
D2 Limited Slip 4.10
L73 Limited Slip 3.73
 






A bad front drive shaft will make all kinds of rattling, chain types noises when the cv end fails. I suggest removing it and going for a drive to see if the noise persists. If it goes away, then you have eliminated the front diff as the issue. Try this and post back up here with your findings.

Beware the driveline will be in a bind when you start the removal, and may release with a pop when the front shaft is removed if parked on an incline, so be sure to chock the tires if you raise the vehicle. Keep this chock with you , as the vehicle will now roll slowly when in park with no front drive shaft in place.
 






20161012_184119_zpslhzhmlzq.jpg
Koda2000 - This is the tag, Im guessing 3.73?
The door jam sticker has an odd VOID across it. I assume someone tried to remove it at one point and only the top layer came off leaving just the void?
20161012_184119_zpslhzhmlzq.jpg
20161012_184004_zps3djksh4g.jpg



Turdle - I haven't had an opportunity to remove the front drive shaft yet but will this week sometime and post results here.
 












Or you can always fully support the truck in the air, put the transmission in neutral, rotate the driveshaft while counting tire rotations.

If it's 3.73, then the tire will go around once while the driveshaft spins 3.73 times.

Other common ratios used in Explorers (not just V8 AWD):
3.55
4.10
 






Take your VIN number an go to Ford's ETIS web site. There's an option there that will tell you everything you ever wanted to know how your vehicle was built/optioned. 3:73 was a very common ratio for the V8 Ex's and Mountaineers.

Link to ETIS:
http://www.etis.ford.com/

Once the basic info is displayed for your vehicle there's a button to click on for more info. It says "There are more minor features for this vehicle, click to expand this list."

Great resource. Ratio was there.
 






A bad front drive shaft will make all kinds of rattling, chain types noises when the cv end fails. I suggest removing it and going for a drive to see if the noise persists. If it goes away, then you have eliminated the front diff as the issue. Try this and post back up here with your findings.
I removed the front drive shaft and the noise and vibration are still there unfortunately. Another noise has developed that may help with the diagnosis. A squeak at low speeds that corresponds to tire rotation. Also when turning the growling noise and vibration go away.
Should I test any other component before diving into the front differential?
Also, are 4x4 and AWD front differentials the same? What year range fits the 2000 model? Can a differential from a 4.0 be used in a 5.0?
Thanks.
 






Are you sure it isn't the brakes?

Jack up the front and spin the wheels by hand then see what you hear.
 






Are you sure it isn't the brakes?

Jack up the front and spin the wheels by hand then see what you hear.
Brakes are good. No issues specifically with them.
 






Growling noises can mean bad front wheel bearing hubs assemblies. As far as I know (other than the gear ratio) all the explorer front diffs are the same (4x4 or AWD).
 






Growling noises can mean bad front wheel bearing hubs assemblies. As far as I know (other than the gear ratio) all the explorer front diffs are the same (4x4 or AWD).
I think you may have nailed it. :)
Noise is the same whether Im going straight or turning left, but disappears turning right. No play in the wheels however.
 






I just ordered a wheel hub and bearings. Will post results once theyre in.
 






I just ordered a wheel hub and bearings. Will post results once theyre in.

The hub assemblies are the front wheel bearings on the 4x4/AWD models. Not that hard to replace other than dealing with the large axle nut and 3 large bolts that hold the hub onto the knuckle.
 






The hub assemblies are the front wheel bearings on the 4x4/AWD models. Not that hard to replace other than dealing with the large axle nut and 3 large bolts that hold the hub onto the knuckle.

Bummer. Fixing the wheel bearing didn't fix the problem. :/

Im thinking the next step is pulling the cover off the front diff and just check for any metal or weirdness.
 






I had the same type of noise on my explorer, over the past couple of years I've replaced...

both Hub & Bearing Assemblies
both front Calipers & Brake Pads
both Rotors
both CV Joints
front Differential,
and replaced the CV joint on the Propeller Shaft

Noise still exists. Turns out it's the tires, if I roll down my window while driving on pavement it sounds like I have knobby tires on, but they're all season. I've got the shake too, especially around 65 mph.

I've put enough parts on the vehicle trying to fix it to have bought 3 sets of excellent tires. So, put some tires on before you replace the entire front end like I did.
 






I had the same type of noise on my explorer, over the past couple of years I've replaced...

both Hub & Bearing Assemblies
both front Calipers & Brake Pads
both Rotors
both CV Joints
front Differential,
and replaced the CV joint on the Propeller Shaft

Noise still exists. Turns out it's the tires, if I roll down my window while driving on pavement it sounds like I have knobby tires on, but they're all season. I've got the shake too, especially around 65 mph.

I've put enough parts on the vehicle trying to fix it to have bought 3 sets of excellent tires. So, put some tires on before you replace the entire front end like I did.

Thanks for the advice. The noise started happening rather suddenly though. I would think if it was the tires wearing in an odd way it would happen gradually.

I was able to get all but one of the diff cover bolts out and swivel it aside slightly. Gear oil was clear for the most part with no metal. I cant get that last bolt out though without dropping it so Its hard to see with real detail the condition of the gears. Do I need to remove the CV axles from the wheel hubs before I loosen the diff mounting bolts to lower it slightly?
 






I think it is best to remove the cv axles, then drop the diff. I don't think it "can" drop due to the angles of the cv axles. They will not go further outboard, if this is what you were thinking.
The diff also has to go slightly rearward to drop it out.

popping the cv axles out is not really very difficult, a cv can be changed on the trail in about 30 minutes for an experienced explorer DIY'er like you are about to become. :thumbsup:

This will help

http://www.explorerforum.com/forums/index.php?threads/cv-axle-replacement-how-to-pictures.187964/
 






Yep, changing a CVJ is pretty much the same as changing a hub & bearing assembly, only difference is you have to yank the CV out and push the new one in, kind of like pulling a socket off of an extension. You don't have to remove the hub and bearing assembly though.

When I changed my Diff. I put the vehicle on stands and pulled everything with the Diff being last.

The tire issue I had I believe was due to the sidewalls collapsing, so the roaring came on pretty quick with mine to. At the time I had to drive across a mountainous road twice a day, so the hard cornering is likely what caused the tires to go south. Although a bad hub & bearing assembly will make a similar noise. I took 2 new H & B Assemblies back to the parts store, because I was convinced they were bad. It took longer to go to the parts store and back than it did to pull the old one, put the new one on test drive it and then put the old one back on again. lol Being convinced it wasn't the bearings I started replacing other things, so I ended up with a completely new front end, but the noise was just as bad.

You might want to replace the shocks and any sway link kits that have fallen off as well. I think I forgot to mention, I replaced the upper control arms to.

P.S. I've got a perfectly good differential if you need one. :thumbsup:
 



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I know what Im doing the rest of the day :p Ill rotate my tires while Im at it to troubleshoot them.

Supposing the diff and tires check out fine and still having the issue. Could it be the transfer case? It doesn't roll with the FDS removed and in park. Could the TC make the growling noise issue described above? Once everything is put back together and FDS re installed Ill check to see if all the wheels are moving while in drive (gonna be interesting checking that as I dont own a lift). That would tell me the viscous coupling is working, but would that even make a noise if it failed?
 






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