Full rear axle rebuild at 95k - Grenaded after fluid change

[Reaper308]

This is why I have always been a big fan of flushing fluids regularly maybe sooner than others and replacing the diff covers on these trucks with something we can drain. Sucks that this happened to you but I agree this could have been coming no matter if you had changed the fluids or not but I believe it probably did take what ever “if anything” that was in the bottom of the diff and resuspended it in the new fluids. Only way to make sure is drain completely and flush then refill. And that’s no guarantee it wouldn’t have happened but I would guess you probably would have had better odds. Again sorry you had that happen, especially away from home like that!

 

[FordTechOne]

So it’s a 2018 and the fluid was changed for the first time at 95k miles?

The 150k interval is for “Normal” operating conditions. That’s defined as mild temperatures, all highway driving, level terrain, and no towing, hauling, or off-road use. So that’s essentially nobody’s use case.

Not having a drain plug has nothing to do with the failure; the metal in the differential is due to the bearing failure, not the cause of it.

When gear oil breaks down or the fluid level becomes low, the pinion bearings are typically the first to be damaged. That’s because they have higher preload and spin at 4 times the speed of the differential bearings. Additionally, they are higher in the case, so low fluid starves them of lubrication.

It sounds like the fluid was simply worn out and whatever metal particles were suspended in it were keeping it quiet enough for you not to notice. When the fluid was changed the wear became apparent.

 

[Drgonzo3000]

So it’s a 2018 and the fluid was changed for the first time at 95k miles?

The 150k interval is for “Normal” operating conditions. That’s defined as mild temperatures, all highway driving, level terrain, and no towing, hauling, or off-road use. So that’s essentially nobody’s use case.

Not having a drain plug has nothing to do with the failure; the metal in the differential is due to the bearing failure, not the cause of it.

When gear oil breaks down or the fluid level becomes low, the pinion bearings are typically the first to be damaged. That’s because they have higher preload and spin at 4 times the speed of the differential bearings. Additionally, they are higher in the case, so low fluid starves them of lubrication.

It sounds like the fluid was simply worn out and whatever metal particles were suspended in it were keeping it quiet enough for you not to notice. When the fluid was changed the wear became apparent.

2017

Your interval statement, sounds more like the interval was created by Ford for non-normal circumstances since it's nobody's' use case. Everything you listed is what the vehicle is used for normally, why the hell else would you buy a truck.

Not having a drain plug allowed whatever sediment/material was in the dif to remain there when following Fords own process for sucking the old fluid out. Internal damage is not the only thing that causes that sediment/material. "Normal" wear and tear causes it. You must not have opened a lot of 100k+ difs if you think different.

Pinion bearing being starved of fluid, that's a design problem.

Sure the gear oil was broken down, Maybe Ford shouldn't recommend 150k fluid changes for owning and driving a truck as a truck....

 

[Old-Raptor-guy]

So it’s a 2018 and the fluid was changed for the first time at 95k miles?

The 150k interval is for “Normal” operating conditions. That’s defined as mild temperatures, all highway driving, level terrain, and no towing, hauling, or off-road use. So that’s essentially nobody’s use case.

Not having a drain plug has nothing to do with the failure; the metal in the differential is due to the bearing failure, not the cause of it.

When gear oil breaks down or the fluid level becomes low, the pinion bearings are typically the first to be damaged. That’s because they have higher preload and spin at 4 times the speed of the differential bearings. Additionally, they are higher in the case, so low fluid starves them of lubrication.

It sounds like the fluid was simply worn out and whatever metal particles were suspended in it were keeping it quiet enough for you not to notice. When the fluid was changed the wear became apparent.

This x 1000.
Seriously factory recommendations are "best case scenario "!!!!!!!!!!

 

[Old-Raptor-guy]

I will add, if you look at your pinon/pinion seal AND the fill level plug. The fill level is actually just a hair BELOW the pinion seal.

The pinion seal is not designed to hold back a FLOOD of gear oil but just a small amount/splash.

Same as a rear main seal on an engine.

Given that fact, the (outer) pinion bearing is the first to fail as it lives the hardest life.

 

[FordTechOne]

2017

Your interval statement, sounds more like the interval was created by Ford for non-normal circumstances since it's nobody's' use case. Everything you listed is what the vehicle is used for normally, why the hell else would you buy a truck.

It’s called cost of ownership metrics. To stay competitive, manufacturers benchmark industry standards to set maintenance intervals. You need to use discretion and tailor your maintenance to how your vehicle is used.

Do you also change your oil every 10,000 miles because that’s the maximum allowable interval under perfect conditions? I’d hope not.

Not having a drain plug allowed whatever sediment/material was in the dif to remain there when following Fords own process for sucking the old fluid out. Internal damage is not the only thing that causes that sediment/material. "Normal" wear and tear causes it. You must not have opened a lot of 100k+ difs if you think different.

As @Old-Raptor-guy stated, axles have not traditionally included drain plugs for almost a century. Particles in the fluid from normal wear are not going to cause a sudden failure; obviously you’ve never cleaned a magnet inside a differential. If there is metal debris large enough to cause damage then a bearing/component has already failed. It’s also not a big deal to remove the axle housing cover to clean it; that procedure is in the WSM as well.

Pinion bearing being starved of fluid, that's a design problem.

The Ford Sterling 9.75 has been in production for over a quarter of a century. There is no “design problem”. Your statements are unfounded and simply ridiculous.

Sure the gear oil was broken down, Maybe Ford shouldn't recommend 150k fluid changes for owning and driving a truck as a truck....

Maybe use some common sense that an 8 year old truck with 100k miles should have had the axle fluid changed well before that time and mileage. Especially if you bought it used and have no idea how it was used or treated by the previous owner.

 

[Drgonzo3000]

It’s called cost of ownership metrics. To stay competitive, manufacturers benchmark industry standards to set maintenance intervals. You need to use discretion and tailor your maintenance to how your vehicle is used.

Do you also change your oil every 10,000 miles because that’s the maximum allowable interval under perfect conditions? I’d hope not.

As @Old-Raptor-guy stated, axles have not traditionally included drain plugs for almost a century. Particles in the fluid from normal wear are not going to cause a sudden failure; obviously you’ve never cleaned a magnet inside a differential. If there is metal debris large enough to cause damage then a bearing/component has already failed. It’s also not a big deal to remove the axle housing cover to clean it; that procedure is in the WSM as well.


The Ford Sterling 9.75 has been in production for over a quarter of a century. There is no “design problem”. Your statements are unfounded and simply ridiculous.

Maybe use some common sense that an 8 year old truck with 100k miles should have had the axle fluid changed well before that time and mileage. Especially if you bought it used and have no idea how it was used or treated by the previous owner.

Cost of ownership metrics, you mean the shit Ford prints in everyone's owners manuals that tells them when they should be doing this thing. God forbid people actually follow the instruction manual. But according to you every single Ford truck owner should know better and it's their own fault when it shit breaks cause Ford is too ******* stupid to actual print "Metrics" that support regular owner usage.

Rear Diff not having a drain plug from factory just means those Manufactures have been dry ******* you all for that long. Funny how every aftermarket diff includes one, and a magnetic plug. Probably cause they know better. I have half a dozen B4G rear diffs here in my shop along with the same amount of Getrag transmissions, so yeah IDK what a magnetic drain plug looks like when it comes out or how that sludge does indeed affect every single thing it comes in contact with and will destroy bearing races in no time.

East Coast Gear Supply here in NC did the repairs on my truck and they even state the 9.75 rears are know for their pinion bearing failures at like 90k. Mine had the same pitted races as every single one they have found or encountered. Hell they do they so much it only took them 5 hours to rebuilt the entire rear end of the truck.

Now that it's all fixed, time to sell it and buy something better.



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[TwizzleStix]

Cost of ownership metrics, you mean the shit Ford prints in everyone's owners manuals that tells them when they should be doing this thing. God forbid people actually follow the instruction manual. But according to you every single Ford truck owner should know better and it's their own fault when it shit breaks cause Ford is too ******* stupid to actual print "Metrics" that support regular owner usage.

Rear Diff not having a drain plug from factory just means those Manufactures have been dry ******* you all for that long. Funny how every aftermarket diff includes one, and a magnetic plug. Probably cause they know better. I have half a dozen B4G rear diffs here in my shop along with the same amount of Getrag transmissions, so yeah IDK what a magnetic drain plug looks like when it comes out or how that sludge does indeed affect every single thing it comes in contact with and will destroy bearing races in no time.

East Coast Gear Supply here in NC did the repairs on my truck and they even state the 9.75 rears are know for their pinion bearing failures at like 90k. Mine had the same pitted races as every single one they have found or encountered. Hell they do they so much it only took them 5 hours to rebuilt the entire rear end of the truck.

Now that it's all fixed, time to sell it and buy something better.



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Really dude? You need to just f*ck off and die. Sell your Ford and buy some toyota, gm, or fiat crap. By felicia

 

[raptorman]

C'mon, fellas, why so defensive? I appreciate the OP for posting, and I will take his advice. This Forum has helped me immensely in my 13 years of Gen 1 ownership. Let's not stoop to name calling and insults, heaven knows we're getting enough that these days. Let's just continue to brag about our Raptors and help others avoid breakdowns and expensive repairs.

 

[CRP]

Posting my experience so others can be aware of this issue when doing the rear dif fluid change.

I had a trip planned, about 2k miles in 2 weeks, with some of it being in the mountains, Tail of the Dragon, etc. Truck just turned 95k so I decided to send it to my buddies shop for fluid changes. Trans, Transfer case, dif, brakes, etc. Truck was in great shape, no issues and regular maintenance done. First part of my trip was about 700 miles, after which I noticed a slight whine coming from the rear end. Tone changed with speed. Jacked it up and found the noise was coming from the rear dif. checked fluid and all was good. Called my buddy and he said the fluid came out clean, but noted that the rear Dif doesn't have a drain and they just use a vacuum to extract the fluid per Ford as to not have to remove the dif cover to drain and then have to reseal it. Not much I can do since I'm 11 hours from home so I continue to drive it and monitor. noise never changed and could't be heard with the AC or radio on.

Once back home I drop it off to him to take a look. popped the rear dif cover and lots of metal in the new fluid. Gear shows some signs of wear. 100% certain the noise is the pinion bearing which looks to be a common occurrence with these rear ends. But why did it decided to grenade itself after the fluid change? We are pretty sure this has to do with the bad rear dif cover design. The lack of a drain, needing to suction out fluid on the oil change and no magnetic plug all played a part.

Since there is no drain, there is no way to actually get any material/sludge off the bottom of the dif unless the cover is pulled, where as an actual drain would allow it to come out. No drain means no magnet to stop any normal wear and tear material from circulating and damaging the dif even more. Lastly, adding new fluid with the material/sludge still sitting at the bottom does nothign more that agitate it and resuspend it in the fluid which we are sure is what actually grenaded this rear dif. Basically changing the fluid causes the crap at the bottom of the dif to mix into the new fluid and tore up the dif.

So I'm looking at about $2,500 for a full rear axle rebuild now cause Ford wasn't smart enough to put a drain plug on their rear difs.

So if your coming up on fluid change, make sure they pull the cover completely off and flush out the rear dif. I'd also advise picking up a new rear dif cover that has an actual drain on it and add a magnetic drain plug to it. I'm having a Splicer cover and gasket installed when they do the rebuild on mine this week.

Did you get a grinding sound, or more of an off and on humming, like something was out of balance? Mine goes in next week to check for the pinion bearings. i'm getting the humming like something is out of balance. Gets worse at higher speeds. I just had my wheel bearing & hubs done, so I know its not those. Sounds like its coming from the rear, but who knows. Mine is a 2020 with less than 60k.