Open to Limited slip rear

OK schools out and my to do list is huge (new hubs and brake jobs for the DD ... yay wheel bearings), but some of that to do list is for my truck. Bed should be coming off and it will be time to get to work on the back end and frame.

According to my tags I should have a open diff. I would like a limited slip rear. Two questions would be is there any donor vehicles that would fit the truck? Its my understanding 1983-2014 all use the 8.8 rear, but a which ones could I use for a full rear end swap? It be nice to get one maybe rated for a higher weight.

IF that does not become a possibility how hard is the conversion? I see JBG has a bunch of 8.8 full carrier options  from OEM to Eaton.

Internet research is one thing, if one of the guru's here has direct experience its another.

With that said, there is a 8.8 LS on my van, the rear is not swapable, but I should be able to gut that over correct? Granted it may not be worth the hassle depending on how many miles are on it.

TheScatch wrote

Two questions would be is there any donor vehicles that would fit the truck? Its my understanding 1983-2014 all use the 8.8 rear, but a which ones could I use for a full rear end swap? It be nice to get one maybe rated for a higher weight.

IF that does not become a possibility how hard is the conversion? I see JBG has a bunch of 8.8 full carrier options  from OEM to Eaton.

Well, any 8.8 rear end from an F150 4x2 or 4x4 up to 1996 will definitely swap over. I can't answer on the 1997-up trucks. I thought they had different bolt patterns for the wheels...but that was just an assumption of mine, no experience.

There are some really good videos on Youtube regarding the gear/carrier swap. Just search on Mustang videos...they have the 8.8 as well. I've watched a couple of them and they're pretty good.

Do you have experience with TractionLok-type limited slips?  Do you know that's what you want?  Everyione has their own opinions on what they like.  Personally my opinion is that clutch-type limited slip diffs like the TractionLok are my second-to-last choice, significantly below an open diff but above a spool.  That's with snowy or icy roads in a Minnesota winter being a significant part of my driving.

If you want to look into other options, here's a thread I started on another forum talking about the different options.  Yes, I include my opinions, but I try to keep them separate from the facts so people can understand what the options are and can make their own choices.

Nothing Special wrote

Do you have experience with TractionLok-type limited slips?  Do you know that's what you want?  Everyione has their own opinions on what they like.  Personally my opinion is that clutch-type limited slip diffs like the TractionLok are my second-to-last choice, significantly below an open diff but above a spool.  That's with snowy or icy roads in a Minnesota winter being a significant part of my driving.

If you want to look into other options, here's a thread I started on another forum talking about the different options.  Yes, I include my opinions, but I try to keep them separate from the facts so people can understand what the options are and can make their own choices.

Here to learn, my understanding is LS diffs help better in low traction scenarios.

reading your post now. Are you more of a fan of manual lockers?

TheScatch wrote

reading your post now. Are you more of a fan of manual lockers?

well reading those posts I guess answered that.

Nothing Special wrote

Do you have experience with TractionLok-type limited slips?  Do you know that's what you want?  Everyione has their own opinions on what they like.  Personally my opinion is that clutch-type limited slip diffs like the TractionLok are my second-to-last choice, significantly below an open diff but above a spool.  That's with snowy or icy roads in a Minnesota winter being a significant part of my driving.

If you want to look into other options, here's a thread I started on another forum talking about the different options.  Yes, I include my opinions, but I try to keep them separate from the facts so people can understand what the options are and can make their own choices.

 mud, sand, and snow are my enemies where I will be taking this truck. Snow and Ice when I head up to NY, mud... so much mud in the south, then when I go west it sand can be an issue enroute to some of the ranges like when crossing a wash. So long as you can get good speed and traction most of the time 4wd is never needed.

TheScatch wrote

reading your post now. Are you more of a fan of manual lockers?

I wouldn't say so much that I'm a fan of anything in particular.  Horses for courses as they say, figure out what's best for what you want and go with that.

My thing against clutch-type limited slips is that there is no "sweet spot" for me.  The one in my current truck when I bought it at 161,000 miles was worn out to the point of being no help when needed (I'd spin one rear tire trying to start up the wet driveway at my parents cabin), but was still too "tight" for safe driving on snow (the back end would slide sideways when coasting around a curve).  For people who don't drive in snow I could imagine there's much less of a down-side, so a tight enough limited slip might be a good option.  But in my usage they are too tight long before they are tight enough.


You say that in much of your use with enough speed and traction 4WD isn't needed.  One thing I'd challenge you to consider is using 4WD sooner in those situations and maybe open diffs are right for you.  In many situations traction-aiding diffs aren't as much help as people think.  Or more to the point, open diffs aren't as bad as they think.  Open diffs give the same torque to both sides, limited to the torque required to spin the tire with the least traction.  But they do still send that amount of torque to the other tire, and just because it isn't spinning doesn't mean that it's not still pushing.  Adding a limited slip or locker at best will send enough more torque to that tire to make it spin too.  But if you are in snow, mud, sand or wet grass, chances are that isn't much more torque than the open diff is already sending to it.  So now you do spin both tires and you slide sideways.

Not saying that traction-aiding diffs don't help, but if you don't need them, nothing is as stable as an open diff.

If you do decide you want more traction than open diffs give you, you're not alone (I have lockers in both axles of my Bronco and a Truetrac in the rear of my pickup).  But it's important to know WHY you want and what you want it FOR to figure out WHAT you want.

A limited slip is a nice compromise between help when you need it and good on-road manners.  As I already noted I'm not a fan of the factory clutch-type limited slips.  But the Truetrac (and others like it) don't try to scrub your tires when you coast around corners.  They still will slide you sideways more than an open diff, and won't help as much in some situations.  But they are a simple, pretty good option.  (After having one in the rear of my truck for a couple years now I'd give a qualified recommendation to it for my kind of use.  It does help get started at the stop sign a couple blocks from my house where the right tire is always on ice and the left is on pavement.  But it's just barely good enough there.  And I do have to be a little more careful with the throttle than I did with the worn out factory limited slip to keep it from kicking sideways.  An automatic locker would be more effective and not a lot worse to drive, or an open diff would be not a lot less effective and significantly easier to drive.)

A selectable locker is the best of both worlds, a full spool when you need more traction and the stability of an open diff when you don't.  Or it's the worst of both worlds, a spool when you don't need it anymore and an open diff when you get stuck.  Obviously flipping the switch at the right time or not is what makes the difference there.  People that like them don't mind that inconvenience (and some even prefer the manual choice, like some of us prefer a stick over an auto trans).  I have one in the front of my Bronco and like it there, but I also like not having to switch the rear diffs in either my pickup or Bronco.  Other than that personal preference issue, they do tend to be the most expensive and some seem to have reliability issues (although I think most of those issues are due to bad electrical connections, so they can be addressed and prevented).

An automatic locker (like a Detroit, or any of the "lunchbox" lockers) is sort of a brutal option.  They are very effective, and for most usage are very reliable (anything can be broken if you try hard enough...).  But they also have the worst street manners.  I've driven a lot of miles with them in a rear axle, including in Minnesota winters, and I wouldn't hesitate to do it again.  But even for me the street manners are a significant negative, so I didn't put one in my pickup.  And I wouldn't really want my wife or one of my sons to be driving one in the winter.  They demand that you pay attention to them, which some people just won't be able (or willing) to do.  So while I definitely wouldn't recommend one to you for your usage, if you think it's what you want I won't tell you not to.

Well, I am really going to have to think on it now lol. I'm leaning towards manual lockers so I can run an open diff most of the time then if I need a bit more traction... say one wheel is spinning in a rut or mud then the other can drive. I live in SC, it's wet here, lots of mud but for the trucks I've driven here, so long as you  can get traction on one tire or get enough traction on both not to spin out you can pretty much crawl out of anything. I've seen 2wd and traction boards succeed where just 4wd has failed here. We were not mudding on purpose or doing anything crazy, just simply getting out to spots in the Francis Marion on trails/unimproved roads after a good rain here can be sketchy. Heck getting off the shoulder after a rain here can be sketchy its all wetlands and swamps. Snow and Ice for us is maybe a once a year thing, and I go up to the NE every other year. Like I said...I'm going to have to think on it now for sure.

When I was in Arizona we used to run a lot in the desert. Lots of drifting F-150s, old Toyotas and blazers around dirt roads and running those 50-60mph in 2wd then, off road 4h 40-50mph until you hit a river wash and had to gear down to 4 low. Fun story, seen one guy get lost in a dust cloud and when the convoy made a right, he kept straight, ramped off a burm and knocked three tires off. We had high jacks, shovels and compressors, but getting that straighten out in 120 degrees sucked. That sand is hot and gets into everything.

A lot of people really like selectable lockers in the rear.  The stability of an open diff most of the time, the dead simple positive action of a spool when you need it.

And in a rear axle, especially in a lighter loaded pickup, you can just keep it locked all of the time when you think you'll need it (although I wouldn't do it on snow or ice).  You'll get some instability on sidehills and it's easier to kick the back end out on corners.  But a spool isn't as awful as some people think, especially when it's not too hard to break a tire loose (and face it, it pretty much always is on an unloaded pickup).

The cost and the complexity to set it up originally are probably the biggest downsides.

ARB is the best known and has a good reputation.  The biggest downside is the need to have on-board air to run it (but that gives you the beneficial side-effect of having on-board air).

OX is my preference, and it's what Gary chose for Big Blue's front axle.  It's not available for 9" axles or TTB (it needs a removable diff cover).  The simplest installation for it uses a push-pull cable that you need to route carefully to avoid kinking (and find a place to mount the mechanical lever).  But they also offer electrical actuation (which Gary is using) or air actuation (my choice).

Eaton ELocker is an electrically actuated selectable locker.  One downside to at least some of these is that they disengage and reengage any time you reverse direction.  Not necessarily a deal-breaker, but for those of us that don't like automatic hubs, this is a negative.  From reading the Eaton owner's manual it appears that some of their ELockers do not work like this, but I don't know how to tell what you'd be getting.  And ELockers are the ones that I've heard about the most electrical connection problems (a lot of people end up cutting off Eaton's connectors and either installing their own or just soldering the wires).

There may be other selectable options, but those are the most common ones, and the ones I'm familiar with.

TheScatch wrote

.... Fun story, seen one guy get lost in a dust cloud and when the convoy made a right, he kept straight, ramped off a burm and knocked three tires off. We had high jacks, shovels and compressors, but getting that straighten out in 120 degrees sucked. That sand is hot and gets into everything.

I have a similar story from my dirt bike days.  A big group of us was riding through the northern Michigan woods on a two-track.  I wasn't liking the visibility with the dust that was being kicked up so I kept slowing down to get some distance.  The guys behind me kept passing, but eventually I was second-to-last in line, with the guy behind me doing the same thing I was.

All of a sudden I see bikes scattered everywhere start appearing out of the dust.  I get on the brakes, and the guy behind me does the same thing and we both stop safely.  Turns out the first guy tried to blast through a puddle on the trail, but apparently the ruts had been cut out by a truck with BIG tires!  His bike was standing upright in one of the ruts, completely submerged in muddy water except for the handlebars!  Bike number 2 is laying on its side just behind #1, with only one hand grip sticking out of the water.  There wasn't room in the puddle for anyone else, so all of the rest had to veer off the trail and had varying degrees of luck avoiding the trees.

It wasn't many of us that were able to simply keep riding.  And 5 or 6 of the guys needed to get their trucks in to haul out their bikes (including the two submerged bikes).  No one died, which overall is a good thing.  But Darwin missed an opportunity to improve the gene pool there.

Nothing Special wrote

ARB is the best known and has a good reputation.  The biggest downside is the need to have on-board air to run it (but that gives you the beneficial side-effect of having on-board air).

OX is my preference, and it's what Gary chose for Big Blue's front axle.  It's not available for 9" axles or TTB (it needs a removable diff cover).  The simplest installation for it uses a push-pull cable that you need to route carefully to avoid kinking (and find a place to mount the mechanical lever).  But they also offer electrical actuation (which Gary is using) or air actuation (my choice).

Onboard air is on the build plan. I like the idea of having a button to push vs a lever in the cab.