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Rust on rear end of 2021 F-150 -- any others?

Mr. Zero

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Mine was built in July and I bought it on July 31. Here is what my rear axle/differential look like. Any need to worry? I'm generally pretty laid back about these things, and it appears that what I see on the front is very light surface rust, but wanted to get everyone's opinions. TIA
Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG-3021
Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG-3020
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Dadofjax

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I've had nothing but issues with mine. Traded it off and happy it's gone. Did well on trade in.
I would love to trade mine in due to the great deal I got on it and would actually make money if I could sell or trade it in right now (according to KBB) but can't because my pre-collision error is always on so dealerships won't take a trade in on a truck that doesn't have adaptive cruise, regular cruise, lane departure or a number of safety features. I have been waiting 5 months to get this fixed the first two "ideas" from Ford didnt work and now i am going on over 3 months waiting for a front camera that is on indefinite back order.
 

UGADawg96

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Mine was built in July and I bought it on July 31. Here is what my rear axle/differential look like. Any need to worry? I'm generally pretty laid back about these things, and it appears that what I see on the front is very light surface rust, but wanted to get everyone's opinions. TIA
IMG-3021.jpg
IMG-3020.jpg
Only Tremors should have orange pumpkins, hah! I'd recommend cleaning it up.... ymmv.
 
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Daily22ssv

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I would love to trade mine in due to the great deal I got on it and would actually make money if I could sell or trade it in right now (according to KBB) but can't because my pre-collision error is always on so dealerships won't take a trade in on a truck that doesn't have adaptive cruise, regular cruise, lane departure or a number of safety features. I have been waiting 5 months to get this fixed the first two "ideas" from Ford didnt work and now i am going on over 3 months waiting for a front camera that is on indefinite back order.
I feel your pain on that one! I was in parts queue wait for months. I also had that issue but was intermittent when the front camra would get wet.
 

Dadofjax

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I feel your pain on that one! I was in parts queue wait for months. I also had that issue but was intermittent when the front camra would get wet.
I would get the pre-collison/front camer error when the sun hit it. They replaced one of the control modules a few months and ago and now the error never goes away. At least it doesnt beep every 10 seconds now I guess.
 

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JeffC57

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Mine was built in July and I bought it on July 31. Here is what my rear axle/differential look like. Any need to worry? I'm generally pretty laid back about these things, and it appears that what I see on the front is very light surface rust, but wanted to get everyone's opinions. TIA
IMG-3021.jpg
IMG-3020.jpg
My Lariat was built and delivered about the same as yours except KC build. It has similar pumpkin rust in those spots on the engine side of diff housing plus some near the drive shaft linkage. The tailgate side of the diff housing looks clean like yours. I can't find any other underside rust. My theory is this is a subassembly that is stored outdoors until needed for the build. Or perhaps these subassemblies are shipped by rail or flat bed truck and exposed to the elements while in route to the final assembly plant. I'm not bothered by it. Those that are may consider safely jacking the rear end and applying some flat black Rustoleum to the effected area.
 

Mike D

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That's what mine looked like, it was a March 2021 KC build 3.55 gears. I took a wire brush, Rust-Oleum and some undercarriage spray to it, problem fixed. Didn't want to wait or rely on the dealership. One of the first things I did on the dealer lot was look at the rear-end, thanks to this form. Now, if it was all over the rear-end, I wouldn't have taken possession of the truck.
 

Kingtermite

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Are people still seeing this on newer builds or did Ford fix this? I've got a 9/20 build date and wondering if I might see this or not.
 

currybob

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These truck builds look worse during the winter months from the salt they use on the roads.

The trucks get driven to storage lots and loading. The salt exposure starts rusting the undercarriage that has already been stored outdoors for who know how long.
 

twelpo19

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"Rustgate" is real. Truck was built 1/21, purchased 3/21 and had contacted the dealer as only had 300 miles on it with bad rust everywhere. (FYI I live in TX -- no snow except this year.) The dealer eventually said they would fix but did not believe they would take the time and correct fully so did it myself while installing airbags for the rear. Explanation given was Ford did not paint the axles (and other parts) as rust would only be surface. For me this was unacceptable on any new truck, much less one costing $73K.

Advice is to check out and get fixed by the dealer unless as picky as I am about my truck.

Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG_2217
Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG_2219
Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG_2563
 

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Bravo36

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Compared to mine, you did a great job. Dealership did mine, and as you would assume, a half-assed job. Not quite to the point where I can crawl around underneath mine yet.
 

2021KR

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Picked up mine last week and didn't notice anything looking from the rear but a closer look revealed some light rust. Dealer asked me to bring it in tomorrow for documentation and repair. The muffler bracket looks the same as my 2019 but the the 2021 has more rust on the differential.

Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG_8524
Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG_8526
Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG_8529
 

2021KR

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Dealer documented rust with pics and will send to Ford.

Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG_8542
Ford F-150 Rust on rear end of 2021 F-150 -- any others? IMG_8541
 

Leadfoot

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Subject: Rust
TO: All Thos who have experience a lot of RUST
* I been in contact with Ford Corp - addressing your Rust issues. Even sent some of your pictures to them
* I'm using the FordTrucks@tFordTucks on the Twitter site & getting them to respond.
* For thos that want to - recomend posting your pictures on this Twitter site. Them seem very interested.
Thank you, will do!
 

Leadfoot

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Keep the charge going! I already told my dealer this is a HOT topic and I'll be on the lookout and I'm sure others will be too now since many of you are championing the issue. I'm not a meteorologist but I consulted with a smart dude in Aerospace industry and by applying a quality coat of zinc chromate primer correctly you'll have not problem. I'm sure Ford Engineers mastered this design before introducting Aluminum but executing with all the factory/subs is the challenge. I was on a project for six months redesigning a product where the main objective of the original design was to be cheaper with less expensive materials but with risk of corrosion if surfaces are not coated/treated correctly. Short story I spent six months of my life with many drawing releases and meetings starting at 5AM till 6PM with VPs and corporate Chief Engineer. Not Fun!
Good info, thank you. Although the biggest problem I, and others, have found is not on the aluminum parts, it's on the iron based materials (rear diff., axles, breaker backing plates, shock mounts, etc.). These items were NOT prepped before or after assembly.
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