Tuning instead of regear

[SALEEN961]

Can you expand on reading the factory file part? What does that mean? Would that be after the ECU is sent to them or is that the same thing?

My only first hand experience tuning this generation of F150s has been with HP Tuners. Their process was to send in my PCM and have them unlock it, after I got it back I had to connect the tuning device to my truck and read the factory file from the PCM. In the case of my 2021 F150, the HP tuners software automatically provided me with a stock file at this point instead of reading it from my PCM because "the control module is not readable". Based on that experience I think that copying your stock file might be part of what they do during the unlock process, but I could be completely wrong. Once you read the factory file from the truck, your options are modifying the file yourself using their software or having someone else like 5 Star or MPT do it for you.

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[konoplya]

Raptor 4.10 gears should fit without any issue if you have a 9.75" semi-float rear axle, they may also fit the 9.75" 3/4 float rear axle, but I haven't seen anyone try it yet. I swapped factory 4.10 gears into my 2014 F150, and I'm using the same limited slip carrier in my 2021 F150.

At the risk of sending the thread off topic, your truck is rated for a minimum of 87 octane and Ford recommends using 91 octane or higher "for best overall vehicle and engine performance". The factory calibration on my 2021 3.5EB starts out with an inferred octane of 89.2 at 0.0 OAR, when the OAR adjusts to -1.0 the inferred octane rating is 98.

I do have the 9.75", but i'm not positive whether its semi-float or full float. I'm leaning towards semi-float (based on my quick research of what that means just now), since my truck is an XL trim. I am however quite positive I don't have limited slip diff either. Not sure if that plays a role in the fitment of 4.10 gears or not.

However, I looked under the front of my truck today and getting back to the original question of how hard it would be to change out the front gears, I took some pics of what's underneath. The front diff seems like its quite accessible (unless I'm completely wrong here) to be able to swap them out without taking out the steering rack. Removing that skid plate should give access to get in there, no? There also seems to be a drain plug on the side to drain the fluid (not sure about refilling it though, is the procedure similar to the rear diff?).

 

[konoplya]

My only first hand experience tuning this generation of F150s has been with HP Tuners. Their process was to send in my PCM and have them unlock it, after I got it back I had to connect the tuning device to my truck and read the factory file from the PCM. In the case of my 2021 F150, the HP tuners software automatically provided me with a stock file at this point instead of reading it from my PCM because "the control module is not readable". Based on that experience I think that copying your stock file might be part of what they do during the unlock process, but I could be completely wrong. Once you read the factory file from the truck, your options are modifying the file yourself using their software or having someone else like 5 Star or MPT do it for you.

I'm going to give Cobb a call and ask them in detail how that works.

 

[SALEEN961]

I do have the 9.75", but i'm not positive whether its semi-float or full float. I'm leaning towards semi-float (based on my quick research of what that means just now), since my truck is an XL trim. I am however quite positive I don't have limited slip diff either. Not sure if that plays a role in the fitment of 4.10 gears or not.

However, I looked under the front of my truck today and getting back to the original question of how hard it would be to change out the front gears, I took some pics of what's underneath. The front diff seems like its quite accessible (unless I'm completely wrong here) to be able to swap them out without taking out the steering rack. Removing that skid plate should give access to get in there, no? There also seems to be a drain plug on the side to drain the fluid (not sure about refilling it though, is the procedure similar to the rear diff?).

It does look like you have much better access to the front differential than you would on a stock F150. You still have to remove the axle shafts to allow for removal of the carrier assembly for a ring and pinion change, so there's still a fair amount of work involved. I wouldn't expect that you should have to pay any extra for a ring and pinion change just because your truck is lifted, but I wouldn't expect a discount either as shops unfamiliar with your lift kit may want to play it safe and not commit to a discount up front. The plug on the side of your differential is the fill plug, our trucks don't have drain plugs on the differentials from the factory.

I do wonder if removing the steering rack is really necessary on stock trucks. I often see service manuals that suggest removing components that don't need to be touched, but I haven't dropped the front diff in a 2021+ F150 yet. I can say that on my 2014 F150, there was plenty of room to drop the front diff out. My 2021 doesn't look significantly different from my 2014, but sometimes a 1 millimeter difference in clearance is all it takes to make an easy job a complete PITA.

 

[Eighthtry]

Make sure you know how to properly change those gears, or find someone with plenty of experience doing it.............correctly.

 

[konoplya]

It does look like you have much better access to the front differential than you would on a stock F150. You still have to remove the axle shafts to allow for removal of the carrier assembly for a ring and pinion change, so there's still a fair amount of work involved. I wouldn't expect that you should have to pay any extra for a ring and pinion change just because your truck is lifted, but I wouldn't expect a discount either as shops unfamiliar with your lift kit may want to play it safe and not commit to a discount up front. The plug on the side of your differential is the fill plug, our trucks don't have drain plugs on the differentials from the factory.

I do wonder if removing the steering rack is really necessary on stock trucks. I often see service manuals that suggest removing components that don't need to be touched, but I haven't dropped the front diff in a 2021+ F150 yet. I can say that on my 2014 F150, there was plenty of room to drop the front diff out. My 2021 doesn't look significantly different from my 2014, but sometimes a 1 millimeter difference in clearance is all it takes to make an easy job a complete PITA.

Ah yes, sorry, the fill plug I meant. But basically to change that fluid I can just remove the cover from the front diff to let the fluid out, then replace cover and fill through fill plug, just like the rear? I've read in other posts where users had to go through some hose to pump the fluid out or something to that effect. I'm going to have to stop by a couple of shops and have them look underneath, maybe I can negotiate a slightly better pricing based on what they see.

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