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Installing a Limited Slip Differential (clutch style) for a Super 8.8

Polo08816

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I could write a very long rant about how the driver assistance and safety features on my 2021 are horrible compared the vast majority of the older and modern vehicles I've driven; but in the interest of being concise I'll just say that the traction control system, most drive modes, and the e-locker are completely useless for me and my use case.

90% of time I'm driving my truck, I'm in sport mode with 4A selected and traction control turned off. If the winter weather is really bad, I'm in Sport mode with 4H selected and traction control turned off. For long highway drives in clear weather, I'm in Sport mode with 2H selected and traction control turned off.




I've thought about adding a Torsen front diff to my truck, but right now I just have the Raptor transfer case with mechanical locking 4H installed along with a rear Trac-lok differential. So far I haven't encountered a situation where I feel that adding the front Torsen would have helped me, but I am looking for a good excuse to add one.
Do you have a link to a forum thread about this install?
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SALEEN961

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Do you have a link to a forum thread about this install?
There's a long thread discussing this over on F150Forum.com, it seemed like I was one of the first people to do this swap on a 2021+ F150 so there's lots of discussion over there as a few of us figured out what would be needed.

The parts you need will vary based on your model year and trim level as not all trucks have IWEs, but every truck with a mechanical locking transfer case does use them. I you have any specific questions, feel free to ask and I'll do my best to answer them.

https://www.f150forum.com/f129/lari...rsus-limited-raptor-tod-hi-lock-cases-501782/
 

JExpedition07

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This video Hammaman posted sums up the difference perfectly, for off road applications the factory locker is vastly superior to the Trac-Lock limited slip. Since the limited slip is multiplying torque with clutches, if your low traction side has zero traction at all….zero is pretty much your multiplier. As you can see the Limited slip lifted off the ground cannot spin the tire on the ground and it cannot move. Conversely, the factory G80 locker in the GM 2500 here drives right off of the blocks with the wheel in the air. This is exactly why Ford switched to the selectable locker from the old Trac-Locks in the F-150. In a 4WD pickup that likely will see off road and wheel articulation, a locker provides much better odds of keeping you from getting stuck.

 
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Guys, guys, guys..... the intent of this thread is to start a discussion about installing, using, maintaining, etc. an LSD. We got a little off topic. I meant it to help others who might be interested, like me and maybe even didn't know it was possible, I sure didn't. The thread started out with helpful, interesting comments, but we are going down a rabbit hole now. I suspect folks shy away from jumping in when there are strong comments about removing the E-Locker and replacing it with an LSD as a bad idea. While that may not be the intent, it sounds like it :)

I have a very different opinion about what an "off road" vehicle is. My truck is NOT an off road vehicle. It's a pig, it's big, it's heavy, it has a nice paint job, nice interior, a couple of nice features, no rattles or creaks, just nice. My truck goes on dirt roads, maybe a pot hole or two while towing my Jeep (my off road vehicle) to the off road park.

We all share a common interest here, our Ford F-150's. E-locker, LSD, Torsen, whatever, pros and cons and opinions galore, that's great, I never want to poo poo on any one's experience, interests, ideas, etc. We're all here to learn, tell some lies, share experiences, and more. It helps us all get through this life with some sanity.

I'm disabling my E-locker, I will never use it, it does not provide the performance that I need. A lot of us have Super 8 rear ends. Short of replacing the axle, our traction options are limited. I am, God wiling, learning, gathering and eventually installing an LSD. It makes the most sense for my needs. My Jeep has front and rear lockers, they are amazing off road tools in that vehicle.
 

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Polo08816

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This video Hammaman posted sums up the difference perfectly, for off road applications the factory locker is vastly superior to the Trac-Lock limited slip. Since the limited slip is multiplying torque with clutches, if your low traction side has zero traction at all….zero is pretty much your multiplier. As you can see the Limited slip lifted off the ground cannot spin the tire on the ground and it cannot move. Conversely, the factory G80 locker in the GM 2500 here drives right off of the blocks with the wheel in the air. This is exactly why Ford switched to the selectable locker from the old Trac-Locks in the F-150. In a 4WD pickup that likely will see off road and wheel articulation, a locker provides much better odds of keeping you from getting stuck.

If I were going to be in an off-road situation where I anticipating lifting at least one front tire and one rear tire off the ground, the rear locker would be appropriate.

But I don't think that is a common case with most F150 owners. A 4WD system with a Torsen or clutch based limited slip and a decent traction control system that will allow sufficient wheel slip will be enough for most folks that aren't out there to rock crawl to get unstuck.
 

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If I were going to be in an off-road situation where I anticipating lifting at least one front tire and one rear tire off the ground, the rear locker would be appropriate.

But I don't think that is a common case with most F150 owners. A 4WD system with a Torsen or clutch based limited slip and a decent traction control system that will allow sufficient wheel slip will be enough for most folks that aren't out there to rock crawl to get unstuck.
Exactly! Not everyone uses their truck the same way. An LSD is not for everyone, and an E-Locker is not for everyone. I thought this was a thread about doing an install of an LSD in a Super 8.8, not a debate of which is better. Better depends on how YOU use YOUR truck. We are not all the same, and there is not just one part that works for everyone. I am here to share my knowledge and experience of doing an LSD installation. If you are here, it is probably because you have an interest in this installation.
 

Iconic22F150

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I installed an Eaton TrueTrac in the 9" Nodular case in my 71 Mustang Mach I. Once you have one, you'll add one to everything. They are far superior to a Traction Lock LSD, but that's the only option available today.
Thanks for the info. Off topic but great to know because I’m having an Eaton TrueTrac installed in my ‘73 Mach 1 as we speak.
 

Polo08816

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There's a long thread discussing this over on F150Forum.com, it seemed like I was one of the first people to do this swap on a 2021+ F150 so there's lots of discussion over there as a few of us figured out what would be needed.

The parts you need will vary based on your model year and trim level as not all trucks have IWEs, but every truck with a mechanical locking transfer case does use them. I you have any specific questions, feel free to ask and I'll do my best to answer them.

https://www.f150forum.com/f129/lari...rsus-limited-raptor-tod-hi-lock-cases-501782/
That was a great thread.

I was excited for it up until the point where it was mentioned that the driveshaft would have to get cut down.
 
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Installing an LSD means eventually you will have some extra maintenance to do. A clutch LSD has, well, clutches in it. They are little flat disks between metal disks to make up a clutch pack if you will. Depending on how you use your truck will impact how often you need to service the clutches. I’ve read conflicting information about the longevity of the clutches, so I won’t get into that, but basically the LSD will “tell” you when it’s time :)

The internet is good and not so good for information, including videos about this and that. I was curious about the process for servicing the LSD clutches when I ran across this video. He talks a bit fast and it is a Mustang, however the process is comparative to our F-150’s. It also shows a tip for reinstalling the S spring.

 

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5.0Screw22

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Installing an LSD means eventually you will have some extra maintenance to do. A clutch LSD has, well, clutches in it. They are little flat disks between metal disks to make up a clutch pack if you will. Depending on how you use your truck will impact how often you need to service the clutches. I’ve read conflicting information about the longevity of the clutches, so I won’t get into that, but basically the LSD will “tell” you when it’s time :)

The internet is good and not so good for information, including videos about this and that. I was curious about the process for servicing the LSD clutches when I ran across this video. He talks a bit fast and it is a Mustang, however the process is comparative to our F-150’s. It also shows a tip for reinstalling the S spring.

That's how I was taught to compress that spring. I cannot imagine trying to do that with a C clamp. This is a good example of how simple the clutch pack is to service. This process does not disrupt the ring and pinion settings.

I am pretty certian that the Super 8.8 does not have the carbon fiber clutches available. In fact, I have not seen anyone selling a rebuild kit, but I am prettey sure that Ford must offer one. If anyone sees a part number for that, please share it here.
 
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Well, all the parts are here finally. New carrier bearings, new ring gear bolts, 2015+ Mustang Traction Loc Super 8 differential, gear oil, friction modifier, RTV, pattern paint, shim kit. Most folks say it takes 3 to 4 hours if you have a lift and 4 to 5 hours on your stomach with your head tilted up :)

I decide to have the side gears modified instead of adjusting the thickness of the C clip. I called several "machine" shops around me, but only a couple will work on "automotive" anything. I dropped the gears off, discussed the goal and left them in their trusty hands. The hope is when the time comes to reinstall the axle shaft the end of the axle will go through the side gear far enough into the carrier to simply install the unmodified C clip 🤞

There are a couple of companies offering modified carriers for the Super 8 equipped straight shaft F-150s, but they cost a lot more. Yukon even offers a purpose built differential for the F-150 called a Dura Grip.

Potential hiccups:
- Backlash, before and after.
- Ring and pinion pattern before and after.
- Chiropractor.

Fun, fun, fun...
 
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I was able to buy the Ford Performance Mustang LSD and take it to my local ring and pinion shop. They modified as necessary to fit. Didn't seem like a big deal for them. I had bought extra C clips and ground them down but the shop didn't like that solution. It works great and wasn't very expensive to install. All in, it was installed for the same price as the yukon without installation.
 
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I was able to buy the Ford Performance Mustang LSD and take it to my local ring and pinion shop.
Yeah, the whole process is a no brainer if you want this setup.

I called a local driveline shop who built CV driveshafts for my Jeeps and does all sorts of driveline, differential service, they wouldn’t do it. I don’t know what the deal is, we’re talking about removing 0.010” 🙂

Elaborate on a “ring and pinion shop?” Transmission, off road, etc. places?
 
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Getting there and learning a lot!

Just about done gathering all the things needed to do this conversion. I have two things left:
-I dismantled the new Ford Performance TracLok differential to harvest the side gears. They need to have a little material removed so the axles will slide into the differential a bit more. I'm going with 0.015 for a little extra buffer for the axle splines.
-I'm not sure what to do about the drive modes that automatically engage the E-locker. I believe I will see a warning message if it's missing. I have a drive mode switch without the E-locker push button, but I bet there is something more I need to do.

FWIW: Be aware that Yukon offers a Ford TracLok Super 8.8 34 spline modified for the 2021+ F-150's. However, I have first hand experience you will get a Yukon Dura Grip instead. I'm sure the Dura Grip is a fine differential, but I wanted the Ford TracLok because it should be dimensionally equivalent to the OEM unit. Not that the Dura Grip won't be, just trying to reduce variables like shimming, pattern changes, bias, etc.
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