Front Diff Replacement

[stkelly]

Hey all! First post.

My 2008 Mountaineer with AWD and 4.6L engine had its front diff fail again. First time it failed at 40K under warranty, 18 months and 22K miles later the pinion bearings/carrier bearings failed again.

At this point I'd like to replace it with a remanufactured unit. I already found one on Ebay and it's being shipped in. Are there any how-to videos or instructions with common gotchas? I searched google and various sites and found how-tos on the older generation Explorers but not the 06 and up version. Are they that different?

The steering rack looks really close, but it still looks like I can drop the diff straight down with no clearance issues. An independent shop that looked at it said the steering rack may need to be removed to get the diff out. So I'm curious if anyone else has removed the diff on an 08 and had any steering rack clearance issues. And of course I would greatly appreciate any other tips you all may have.

Thank in advance!

 

[Ronin8002]

You won't need to remove the steering rack. What you will need to do is remove the swaybar, disconnect the upper control arm from the knuckle, disconnect the tie rod ends from the knuckle, remove the hub nut, and press the spindle off the end of the axle. There is a special tool you can use to pull the axles out of the diff. After that, there's a few bolts that hold the diff to the frame and it comes right out.

If you pm me with an email address I can send you the pages from the shop manual that cover the procedure.

Hey all! First post.

My 2008 Mountaineer with AWD and 4.6L engine had its front diff fail again. First time it failed at 40K under warranty, 18 months and 22K miles later the pinion bearings/carrier bearings failed again.

At this point I'd like to replace it with a remanufactured unit. I already found one on Ebay and it's being shipped in. Are there any how-to videos or instructions with common gotchas? I searched google and various sites and found how-tos on the older generation Explorers but not the 06 and up version. Are they that different?

The steering rack looks really close, but it still looks like I can drop the diff straight down with no clearance issues. An independent shop that looked at it said the steering rack may need to be removed to get the diff out. So I'm curious if anyone else has removed the diff on an 08 and had any steering rack clearance issues. And of course I would greatly appreciate any other tips you all may have.

Thank in advance!

 

[stkelly]

Thanks for the information. It's good to hear the steering rack doesn't need to be removed. From looking at it I really couldn't see why it would need it, but I wanted to confirm.

I've heard you're not supposed to reuse the axle nut. However, most how-tos I see the shops reuse the nut. Is it that important to get a new axle nut?

Any opinion on remanufactured vs used? I saw some really cheap diffs on ebay, but they were generally from 04 and earlier models with over 120K miles. I purchased a reman unit for $1,375 but I'm wondering if it was really necessary to go with a remanufactured unit.

Thanks again.

 

[Ronin8002]

I've re-used axle nuts in the past, but I have also read you're supposed to put new ones in. Never had a problem but if you want to do it once and not have any concerns you might as well do it by the book.

I would recommend buying a reman diff, as long as it has a good warranty.

 

[stkelly]

Success! I replaced the diff this past Friday.

I have lots of pics and video and I'm going through it now so I can post it later. Unfortunately, some of the video isn't that great because I didn't have a helper for a lot of the procedure. For other parts I had my 10 year old son video and he was easily distracted.

Hopefully it will still be helpful for someone wanting to tackle replacing the diff on their own.

I'll post the youtube link once I'm done processing the video.

Ronin8002, thanks for the service manual it definitely helped!

 

[Ronin8002]

glad to help! looking forward to the video!

 

[thebrakeman]

Do you have any idea why your front differential has failed twice? That seems to indicate something external to the diff itself is the cause. Unfortunately, I see you revisiting this issue in the next 18-40k miles. Did you question the dealer that did the job the first time? I would be furious to have something like this fail twice in 62k miles.

 

[stkelly]

Do you have any idea why your front differential has failed twice? That seems to indicate something external to the diff itself is the cause. Unfortunately, I see you revisiting this issue in the next 18-40k miles. Did you question the dealer that did the job the first time? I would be furious to have something like this fail twice in 62k miles.

Believe me, I'm beyond furious it failed twice in 62K miles! I tried talking to Ford and the Ford dealer. They basically stone walled me. An independent that looked into it speculated that the front diff was not shimmed correctly from the factory. When the dealership rebuilt the diff they just used the same shim size and didn't take the time to confirm it was done correctly at the factory. He said not being shimmed correctly would definitely cause the bearings to fail again.

Other than not being setup correctly from the factory, what else could cause a front diff to fail? It only has the driveshaft and two half axles connected to it. All three looked really good, so I'm not sure what else could have caused this issue. If there was something wrong with the driveshaft would I feel it?

I was just thinking, I never double checked the vent hose when I reinstalled it. I probably should have looked for a clog or tear in it that could let in water. The vent hose terminated right above the control arm and it had a white cap in it. Is this correct? At this point I may just order a new one and install it just in case there's an issue with the current one.

It's too bad, because Ford did lose me as a future customer. Because like you said, I was beyond pissed! Not only that it failed twice, but Ford would not offer ANY assistance. I was only 2K miles out of the power-train warranty. It was somewhat ironic I was in the process of negotiating for a new Fusion (right before I found out the diff failed again) and my parents were about to purchase an Edge. We both walked from our deals, my parents got a new Murano (they are at the Nissan dealer right now!) and I ended up getting a used Infiniti G37.

If you have any other suggestions as to what else external could cause a diff to fail please let me know!

Thanks!

BTW, I almost have the video done. Boy it was a lot of hours of video!

 

[Ronin8002]

Yes, you correctly identified the vent tube setup and it sounds like everything is where it should be. The white cap is a kind of check valve that keeps water and debris from getting in. You can check it by removing the hose from the diff and blowing into it...you may'll feel a little restriction due to the valve but otherwise should be able to blow thru it.

Believe me, I'm beyond furious it failed twice in 62K miles! I tried talking to Ford and the Ford dealer. They basically stone walled me. An independent that looked into it speculated that the front diff was not shimmed correctly from the factory. When the dealership rebuilt the diff they just used the same shim size and didn't take the time to confirm it was done correctly at the factory. He said not being shimmed correctly would definitely cause the bearings to fail again.

Other than not being setup correctly from the factory, what else could cause a front diff to fail? It only has the driveshaft and two half axles connected to it. All three looked really good, so I'm not sure what else could have caused this issue. If there was something wrong with the driveshaft would I feel it?

I was just thinking, I never double checked the vent hose when I reinstalled it. I probably should have looked for a clog or tear in it that could let in water. The vent hose terminated right above the control arm and it had a white cap in it. Is this correct? At this point I may just order a new one and install it just in case there's an issue with the current one.

It's too bad, because Ford did lose me as a future customer. Because like you said, I was beyond pissed! Not only that it failed twice, but Ford would not offer ANY assistance. I was only 2K miles out of the power-train warranty. It was somewhat ironic I was in the process of negotiating for a new Fusion (right before I found out the diff failed again) and my parents were about to purchase an Edge. We both walked from our deals, my parents got a new Murano (they are at the Nissan dealer right now!) and I ended up getting a used Infiniti G37.

If you have any other suggestions as to what else external could cause a diff to fail please let me know!

Thanks!

BTW, I almost have the video done. Boy it was a lot of hours of video!

 

[stkelly]

Any ideas as to what else external could cause a front diff to fail? I didn't even check the vent hose. I just ordered a new one with a cap. In my mind it wasn't worth using the old one. I really don't want this diff to fail. As much as I love working on cars, I don't want to revisit this repair 18 months later.

Thanks again.

 

[thebrakeman]

I don't know anything about it, but the shim issue sounds interesting. Is this something you had to re-shim? How do you check this to be sure it's aligned/shimmed correctly? Perhaps that would be worth having a trusted shop measure for you. It might not be a difficult/expensive inspection, but it could allow this new diff to last as intended.

 

[stkelly]

No, I just purchased a remanufactured differential. The shims are inside the differential so I didn't have to make any adjustments to the new one.

The independent said it was very tedious to shim correctly. He said you had to reassemble most of the diff and check the distance on the ring and pinion gear. If it was too tight you had to take it apart again and reshim it. He said that could take up to 40 mins and thought that was why the tech probably didn't take the time to redo it. He said rebuilding the diff on warranty is tight money wise and leaves no room for measurements like this.

I didn't even want to mess with having my old one rebuilt since the last rebuild didn't last. Hopefully the company that rebuilt my remanufactured diff knew what they were doing!

I have to say, everything feels great except I do feel a slight vibration in the gas pedal and floor board when accelerating. I'm pretty sure the truck has always done that so I thought it was normal, but figured I'd ask here. Is this kind of vibration on acceleration normal?

Thanks.