Change Driveline Fluids Early!

[BKinn]

Changed my rear diff, front diff, and transfer case this past weekend due to the advice in this thread (also added the ford performance cover). I'm the 2nd owner, at about 27k miles. Rear diff magnetic drain plug had a fair amount of metal from the break in, as others have shown. Highly recommend this service early!

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[CarbonSteel]

I also did the transfer case with ~1.6 qts Mercon V and the front Dana m190 differential with another quart of valvoline 75w140, more or less. Not sure if that was right for the front diff oil since I realized in retrospect the non Sasquatch has a different front axle that what is primarily being discussed in the thread. Either way, it drove fine on the way home from my hangar.

You used Mercon V or Mercon LV in the transfer case? 75W-140 is no problem in any of the Bronco axles--Dana specifies it for every Advantek axle they manufacture.

 

[userdude]

@CarbonSteel I was picking my Bronco up after the pinion fix and asked the service writer what it might cost to install the FP diff cover. He speculated about $230 (a half hour or so of time plus the diff oil change).

He wasn't quite sure what it would take, though, so he asked one of the mechanics who happened to be right there. That guy hadn't worked on a Bronco yet (he's an older guy, so I assume had some experience) but made a big deal about these set screws that put pressure on something and they have to be done right. So I should definitely bring it in and have them do it... However, he said he didn't know if the Bronco rear diff had these or not.

I don't recall you mentioning these set screws. Do you know what he's talking about?

 

[CarbonSteel]

@CarbonSteel I was picking my Bronco up after the pinion fix and asked the service writer what it might cost to install the FP diff cover. He speculated about $230 (a half hour or so of time plus the diff oil change).

He wasn't quite sure what it would take, though, so he asked one of the mechanics who happened to be right there. That guy hadn't worked on a Bronco yet (he's an older guy, so I assume had some experience) but made a big deal about these set screws that put pressure on something and they have to be done right. So I should definitely bring it in and have them do it... However, he said he didn't know if the Bronco rear diff had these or not.

I don't recall you mentioning these set screws. Do you know what he's talking about?

What in the ever loving....? There are no "set screws" on a differential and no differential has ever had them in my decades of working with them. There have been covers that have studs which are torqued against the bearing caps on certain differentials as a strengthening measure whereas these studs create a "connection" between the cover and the bearing caps to stiffen the main cap area. This can (**may**) help prevent gear damage by limiting the amount of ring gear deflection. These are also known as differential cover "girdles".

Dana axles do not have them and no axle aside from race applications in very specialized use cases have them installed as an OEM. You can totally disregard what he is saying, and I would find another dealer as he is 1000% CLUELESS.

Replacing the OEM cover with a FP cover is a very straightforward process and it requires a minimum of tools, though you do need a torque wrench that can apply 22-30ft-lbs of torque (most any 3/8" torque wrench can do this).

I would be happy to walk you through it, but in any case--find another dealer!

 

[userdude]

What in the ever loving....? There are no "set screws" on a differential and no differential has ever had them in my decades of working with them. There have been covers that have studs which are torqued against the bearing caps on certain differentials as a strengthening measure whereas these studs create a "connection" between the cover and the bearing caps to stiffen the main cap area. This can (**may**) help prevent gear damage by limiting the amount of ring deflection. These are also known as differential cover "girdles".

Dana axles do not have them and no axle aside from race applications in very specialized use cases have them installed as an OEM. You can totally disregard what he is saying, and I would find another dealer as he is 1000% CLUELESS.

Replacing the OEM cover with a FP cover is a very straightforward process and it requires a minimum of tools, though you do need a torque wrench that can apply 22-30ft-lbs of torque (most any 3/8" torque wrench can do this).

I would be happy to walk you through it, but in any case--find another dealer!

The funny part was the service writer, one of the more experienced ones, was watching him describe it and when he walked away, he just looked at me and shrugged his shoulders. lol I just took it as him trying to drum up business. Thanks!

 

[CarbonSteel]

The funny part was the service writer, one of the more experienced ones, was watching him describe it and when he walked away, he just looked at me and shrugged his shoulders. lol I just took it as him trying to drum up business. Thanks!

Yep; as my grandpappy used to say..."Boy, remember that you can only stack bovine scatology so high before it falls on you and you are covered in it...so don't let it get that high before you walk away."

 

[LSW]

You used Mercon V or Mercon LV in the transfer case? 75W-140 is no problem in any of the Bronco axles--Dana specifies it for every Advantek axle they manufacture.

My fault, I did use Mercon LV, forgot the L when I made the post. Thanks for the reassurance on the non-sasquatch front axle with 75w140.

 

[CarbonSteel]

My fault, I did use Mercon LV, forgot the L when I made the post. Thanks for the reassurance on the non-sasquatch front axle with 75w140.

No worries. You can edit and change it.

 

[Brian2011]

Changed all fluids, Front, Rear, Transfer case, Manual Trans, Oil, Thanks to all the Input from this thread.
Changed rear diff cover to ford performance, I used the OEM hardware that came with the cover and reused the OEM rubber and steel gasket IMO there was plenty of thread with the OEM hardware and a little red thread locker.

 

[CarbonSteel]

IMO there was plenty of thread with the OEM hardware and a little red thread locker.

How much thread extended past the gasket?

 

[Brian2011]

How much thread extended past the gasket?

Did not measure with a micrometer but a good 7-8 turns before torque sequence

 

[CarbonSteel]

Did not measure with a micrometer but a good 7-8 turns before torque sequence

Yeah, I did not have that which is why I went with longer bolts.

 

[87-Z28]

As for the MPG hit due to 75W-140 vs. 75W-90, a headwind, hills/mountains, higher load, or your right foot will have more of an impact on MPG than a viscosity change ever will.

Heavy 13.5” wide 37s have a much greater affect on MPG than a gear oil viscosity change in the rear diff. Yet most don’t question that.

 

[2023bronco]

Two comments and a question.

First, the cover is painted, not powder coated, which is disappointing.

Second, consider cleaning out the bottom portion of the housing with brake cleaner and lint-free rags. There are large basins in the very bottom - so all the oil does not drain out. I collected a ton of metallic oil from there. There's no need to go crazy with the brake clean and spray everywhere. But pay attention to those basins. I assume they are the result of strengthening ribs.

Third, why are people using the original gasket? The cover comes with one. Is the original gasket also torqued to 30 ft lb like the new one?

PS
Don't use red Loctite on anything unless you want to torch something off the next time.

 

[CarbonSteel]

Two comments and a question.

First, the cover is painted, not powder coated, which is disappointing.

Second, consider cleaning out the bottom portion of the housing with brake cleaner and lint-free rags. There are large basins in the very bottom - so all the oil does not drain out. I collected a ton of metallic oil from there. There's no need to go crazy with the brake clean and spray everywhere. But pay attention to those basins. I assume they are the result of strengthening ribs.

Third, why are people using the original gasket? The cover comes with one. Is the original gasket also torqued to 30 ft lb like the new one?

PS
Don't use red Loctite on anything unless you want to torch something off the next time.

Clean the basin inside the housing with lint free towels only. Do not introduce brake cleaner into the housing, there is zero need--no advantage--and it will attack the seals.

The OEM gasket can be re-used at least 10 times and given there is no replacement on the market for the one that comes with the FP cover, why would you use it? It is a fiber gasket that would need sealant applied which is messy whereas the OEM gasket comes off with no cleaning required.

I would torque the bolts to 22 nm to start and go up to 25 nm if needed. I would not go 30 lb-ft, you are risking twisting off the bolt.

Ford's torque spec is 20nm + 25 degrees. 30 lb-ft would be about 40nm.

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