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MC1313

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EDIT: Moved everything to the first page including all videos and parts lists. As of 15 August, 2024, all links have been updated and are working. Ping me if you see any that do not.

I just completed changing the fluid in the front axle, transfer case, and rear axle and added a Ford Performance cover on the rear axle at the same time. I changed all 3 at 2500 miles, the Bronco now has 5000 miles on it, so another 2500 mile run on all three.

I did not find anything unexpected and overall, it was a smooth process--that anyone can do. I am not a professional videographer and so the rear axle has a few videos, but by the time I made it to the transfer case, I had figured it out. Apologies for the multiple videos, bad angles, and having to listen to my voice.

A side note about synthetic gear oil. There have been more misconceptions posted about synthetic oil which includes gear oil than ever should have been. From how they will cause leaks where none existed, to they will delay or prevent mechanical break-in, to they do not protect as well as conventional oils. None of that is true.

From at least 1999 through at least 2014 Ford specified 75W-140 synthetic gear oil in their rear axles. From the mid-1990’s until the mid-2010’s many OEMs specified synthetic engine oil and from the mid-2010’s until now nearly all do. If synthetic oil had any of the properties noted above, we would hear of the issues they allegedly create by the tens of thousands especially with the internet amplification that happens today.

In short, synthetic oil (in any form) will not prevent or delay break-in nor cause any issues in modern applications. There is also nothing that a conventional oil can do that a synthetic cannot do better—unless you have a pre-1980 engine, then the requirements for additives such as ZDDP are not in synthetics, but those are in the minority and certainly do not apply to a 6G Bronco.

I am happy to answer any questions.

This funnel is a lifesaver - https://www.amazon.com/Hopkins-10106B-FloTool-Filler-Refill/dp/B000EH4UXM



Front Axle Video and Parts -



- Amsoil 75W-110 fluid (about 1.2 QTs) - https://www.amsoil.com/p/severe-gear-75w-110-svt/?code=SVTQT-EA

- Permatex 59214 High Temperature Thread Sealant (https://www.amazon.com/Permatex-59214-Temperature-Thread-Sealant/dp/B0002UEOP0)

- I chose 75W-110 because it is the upper viscosity that 75W-90 used to be before the SAE J306 table was updated in 2005 AND because the from axle capacity is so small. I also had it in my stash--I will switch to 75W-140 when it runs out.

For information, the J306 table defines the kinetic viscosity ranges (cSt @ 100°C) that a particular viscosity gear oil must meet in order to be labeled as that viscosity. In 2005, the 75W-90 viscosity range was split into two ranges. The lower range became 75W-90 and the upper range became 75W-110.


Transfer Case Video and Parts-



- Motorcraft Mercon LV fluid (about 1.8QTs) - https://www.amazon.com/Ford-XT-10-QLVC-Oil-Automatic/dp/B07ZTRVLX9

- Permatex 59214 High Temperature Thread Sealant (https://www.amazon.com/Permatex-59214-Temperature-Thread-Sealant/dp/B0002UEOP0)

- I chose Motorcraft Mercon LV versus Amsoil, Red Line, Royal Purple, etc. because there is no combustion by products, the temperatures are nominal, and Motorcraft is cost effective. From my viewpoint, changing standard Motorcraft Mercon LV more often is better than running a premium synthetic longer.


Rear Axle Parts:

- Ford OEM gasket (it is reusable unless damaged) part number is KB3Z 4036 A

- Amsoil 75W-140 fluid (about 2 QTs) - https://www.amsoil.com/p/severe-gear-75w-140-svo/?code=SVOQT-EA

- PTFE Megatape (Gray) - https://www.amazon.com/HERC-15100-1-2X1000-MEGATAPE/dp/B00LO49TV2

- I chose 75W-140 because Dana recommends it for the M220 axle (they also recommend it for the M210 front axle). Any 75W-140 off the shelf (Castrol, Mobil, or Valvoline, etc.) will also work if you do not want to order Amsoil.

- The bolt thread depth in the axle housing is 23mm. If using the OEM rubber and steel gasket with the Ford Performance cover, then you need M8 bolts that are at least 25mm long—if purchasing new ones, then consider 30MM. IMHO, the supplied bolts with the cover are 20mm and they will be too short for the OEM gasket.

Will the supplied bolts work? Yes. They will grab enough thread to tighten and not leak. Are they optimum? No. Because the face of the axle housing threaded bosses is back chamfered, you are not grabbing much thread despite what is protruding from the cover. Also, consider the parent material is cast iron—if you snag the cover on a drop off, you will wish you had more thread engagement into the housing versus what the supplied 20MM bolts gives.

It should also be noted that I have not found a single source for the fiber composition gaskets which are supplied with the Ford Performance cover. The only gaskets currently in the marketplace for a 12 bolt Advantek axle cover is OEM—either from Ford or Jeep (the Rubicon uses the same rear axle). All other Dana 44 gaskets are for the older generation which is a 10 bolt design.


Video 1 - Tools and Parts -





Video 2 - General Discussion About Cover/Brake Line Clips & Prying on Cover -





Video 3 - Initial Drain -




Video 4 - Inspection and Cavity Discussion -





Scott towel showing metal from cavity:


1723751008510-yk.jpg




Video 5 - Cover Installed and New Brake Clamps -





Video 6 - OEM Brake Clip Construction
-




Rear Cover Hardware (NEW longer flange bolts are needed if using OEM gasket because it is thicker. They are not needed if using the supplied gasket with the Ford cover--use the supplied bolts that come with the cover--I would still consider replacing them with longer bolts considering the minimal thread engagement):



10 Each - Flange Bolts: M8x1.25x25mm long. These are yellow zinc coated to prevent rust—https://belmetric.com/jis-flange-bolt-10-9-coarse-m8x1-25-12mm-wrench/?sku=BF8X25YLW

2 Each - Brake Line Studs: M8x1.25x75mm long. These are black oxide and can rust. A bit of paint or grease can prevent corrosion—https://belmetric.com/m8-double-end-stud-class-10-9-hardened-steel/?sku=SH8X75DBLK

4 Each - Stud Washers. These are extra thick and are yellow zinc coated to prevent rust— https://belmetric.com/fender-washer-hv350-steel-quenched-tempered/?sku=WFEHV8X23YLW

4 Each - Stud Cover and Inner Side Brake Line Clamp Flange Nuts (one goes against the cover and one goes on the inside of brake line clamp)— https://belmetric.com/tall-collar-nut-flange-class-10-steel-din-6331/?sku=NFFH8TALLYLW

2 each - Rear Brake Line Clamps. I believe I used the 3/8", if not then 1/2". You have to drill the holes out to 8MM because they are 1/4" out of the box. Take the rubber off the clamp before attempting to drill. I used a small vise and drill press to drill them out using a few different drill bit to move up slowly— https://www.amazon.com/dp/B07V2YBDS5

2 Each - Stud Outer Side Brake Line Clamp Flange Nuts (these tighten the brake line clamp on the outside— https://belmetric.com/flange-nut-smooth-class-10-steel-din-6923/?sku=NFFH8X13YLW

Magnetic Drain Plugs:

3 Each (if replacing all to be the same) - Low-Pressure 316 Stainless Steel Plug with Hex Drive, Hollow with Magnet, 1/2 Pipe Size https://www.mcmaster.com/1457N14

@redone17

20231103_135210.jpg


20231103_140004.jpg


20231103_155847.jpg


20231103_154827.jpg


20231103_154838.jpg
I noticed you said that you (used 1.8 quarts) is you Bronco have the 4A option? Book calls for 1.3 if not and 1.6 if it does.
I was just curious. Also do you fill transfer case until fluid comes out of top fill hole?
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CarbonSteel

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I noticed you said that you (used 1.8 quarts) is you Bronco have the 4A option? Book calls for 1.3 if not and 1.6 if it does.
I was just curious. Also do you fill transfer case until fluid comes out of top fill hole?
I have a Wildtrak so it does have 4A and yes, I did fill until it comes out of the top hole on the TC.

Hope this helps!
 
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Roger123

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Not sure if this was mentioned (didn't see it on the first page). As mentioned in @popo_patty 's video you can just pop the brake line clips off of the studs with a trim removal tool (they're a Christmas Tree type of clip) and rotate them out of the way. There's no need to remove them from the brake line.

At 34K miles mine wasn't as bad as I was expecting. Some "paste" on the magnet but not too terrible.

I was a bit surprised at the effort required to remove the bolts, looks they might have had a small bit of sealant on them from the factory.

The fill plug was a tad over finger tight (I could have took it out without using a ratchet), didn't expect that either.

It never ceases to amaze me the smell of gear oil. I did my first fluid change on my '67 Bronco in '85, the '22 smells EXACTLY the same, LOL.

Great videos and discussion, thanks for putting in all the effort!

Ford Bronco Change Driveline Fluids Early! IMG_2170


Ford Bronco Change Driveline Fluids Early! IMG_2175


Ford Bronco Change Driveline Fluids Early! IMG_2173
 
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Vcastag

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Did the front diff, transfer case, rear diff (added the ford performance cover), and the transmission fluid (added the ppe deep pan - changed the gasket and filter as well) at basically 17k miles.

Used mercon ulv in the trans, mercon lv in the transfer case, and amsoil severe 75w90 in front and rear diff.

We did run into a couple issues, though nothing too major. The transmission pan stud bolts on the passenger side were tough to get a socket on - very little space between the bolt and the pan. We put about 8.75qts of fluid in total. When we filled the pan cold, we put in about 7qts and that filled to level 5 on the dipstick. We then got the transmission up to my normal operating temperature (about 180F) and the dipstick only had maybe 1-2mm of fluid. Added fluid until it was back to level 4 while idling. A note, the exhaust and cat are right by where you reach for the fill port, and doing it hot requires care.

The biggest issue we had was the ford performance diff cover. The driver side stud bolt broke (see picture) when we torqued it to the specified torque values included with the cover (using a recently calibrated torque wrench). We were lucky that we were able to grab the bolt with pliers. We ended up using a new oem gasket and the factory bolts, and torqued to the stage 1 and 2 values specified in the service manual.

I wish we had read this post first as we wouldnt have torqued it down to the ford performance specs.

Rear diff magnet had some metal mayonnaise (see picture). Other magnets had some metal as well. Transmission pan had some metal on the magnet as well, and the filter looked dark, but the fluid looked fine honestly.

IMG_5761.jpeg
IMG_5759.jpeg
Isn’t the torque stated for 25lbs? I’m about to change out my diff cover this week. Concerned about snapping a bolt.
 

vwarner1411

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Isn’t the torque stated for 25lbs? I’m about to change out my diff cover this week. Concerned about snapping a bolt.
Yes, I believe it’s 25ft lbs (i don’t have the instructions anymore, and we did the work a couple months ago). We reused the original bolts, and the service manual’s torque and angle specs after it broke.

I am planning to get the stainless zinc plated ones recommended in this thread.
 
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Yes, I believe it’s 25ft lbs (i don’t have the instructions anymore, and we did the work a couple months ago). We reused the original bolts, and the service manual’s torque and angle specs after it broke.

I am planning to get the stainless zinc plated ones recommended in this thread.
25 newton meters maximum, not pound-feet @Vcastag.

I would go 15NM, then 20NM, and then 22NM. If no leaks stop there. If there are go to 25NM.

You will almost certainly twist off a bolt with 25 lb-ft.

Here is a torque guide I created:

 

vwarner1411

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25 newton meters maximum, not pound-feet @Vcastag.

I would go 15NM, then 20NM, and then 22NM. If no leaks stop there. If there are go to 25NM.

You will almost certainly twist off a bolt with 25 lb-ft.

Here is a torque guide I created:

Yeah, i honestly don’t remember the exact value anymore. I know we set the torque wrench to what was specified in the included instructions and a bolt broke. After it broke we checked everything to make sure nothing was set wrong, then followed the service manual.
 

MC1313

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Isn’t the torque stated for 25lbs? I’m about to change out my diff cover this week. Concerned about snapping a bolt.
Just my 2 cents use the original gasket or buy one so you don’t have to do it 2 times. I replaced the cover with a (ford performance ) cover and used their gasket and still leaked when torqued to 25 NM took it all apart threw the original gasket in and was good at 22 NM
 

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25 newton meters maximum, not pound-feet @Vcastag.

I would go 15NM, then 20NM, and then 22NM. If no leaks stop there. If there are go to 25NM.

You will almost certainly twist off a bolt with 25 lb-ft.

Here is a torque guide I created:

Even following the 25nm spec I broke one of my bolts, the third or forth one I put back on. The first three went on just fine.....
 
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Even following the 25nm spec I broke one of my bolts, the third or forth one I put back on. The first three went on just fine.....
Were these the OEM bolts or the ones that came with the FP cover? I thought one was class 8.8 and the other was class 10.9

I upgraded mine to a longer class 10.9 (grade 8 equivalent) because I wanted more thread engagement.
 

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Were these the OEM bolts or the ones that came with the FP cover? I thought one was class 8.8 and the other was class 10.9

I upgraded mine to a longer class 10.9 (grade 8 equivalent) because I wanted more thread engagement.
These were the OEM bolts and cover.
 
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These were the OEM bolts and cover.
Gotcha...I cannot remember which was class 8.8 (grade 5 equivalent). I know that class 10.9 can easily handle 25NM for torque.
 

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Finally got to changing my F/R diff and transfer case fluids yesterday as I approch 16k miles :whistle: . I think getting under there and filling that front diff at that poor given angle is the most difficult thing.

I ended up damaging one of my plastic clips on the rear diff, but it went back together and is holding for now. Anyone source one of these individually or is it still a purchase the whole rear brake line kit deal from Ford?
 
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It's still all or nothing AFAIK. @CarbonSteel had a better solution w/ alternative somewhere way back in this thread.
 

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25 newton meters maximum, not pound-feet @Vcastag.

I would go 15NM, then 20NM, and then 22NM. If no leaks stop there. If there are go to 25NM.

You will almost certainly twist off a bolt with 25 lb-ft.

Here is a torque guide I created:

Thank you. Glad I found your response before I had at it!
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