Ford 9" gear swap w/ LS/Locker Questions

[Nothing Special]

I wouldn't eliminate a good limited slip from your options.
Sure you'll need to add friction additive, and the clutches aren't totally maintenance free. But auto trannys use clutches too, and that hasn't kept anyone from using them.
Yukon makes a great limited slip unit. You can select from two different lock-up pressures.
The thing I like about an LS over the True Trac is the LS will still work if you get one wheel in the air. With the True Trac, you have to tap the brake to get it to lock up.

My reason for not thinking a limited slip (other than a gear-type like the TrueTrac) is an acceptable option doesn't necessarily apply to everyone. But when going around a corner, even if just coasting, if the tire traction isn't good enough to slip the diff, then the tires slip. So when coasting around a corner on ice or snow it can cause you to swap ends.

In my experience there's no acceptable "window" of performance for limited slips. Even the worn out one when I bought my F-250 with 161K miles was still too tight to feel safe in winter driving, but definitely too loose to be helpful when I needed it.

If driving on slippery surfaces isn't a factor, then maybe a limited slip can be a good choice for you. But i certainly don't recommend them.

 

[5001craig]

It's a common misconception, especially be people who own them, that automatic lockers (like the Grizzly, Detroit, or lunchbox lockers) lock when you get on the power. They know nothing about power, they work only on relative speed.

When you go around a corner they unlock. The outside tire wants to roll faster than the inside tire and the locker unlocks to allow that to happen. Like I said above, that means you only have one-wheel drive. And what's worse, it's the inside rear tire, the tire with the least weight on it (weight transfers out on a corner). So if you get on the gas too hard it's REALLY easy to spin that tire. So it's the fact that it UNLOCKS that gives the bad handling, not that it locks under power.

Of course, once the inside tire is spinning it quickly catches up with the speed of the outside tire. When that happens the locker relocks. It happens after you got on the power, but it's based on relative tire speed. When it relocks it kind of hammers against the outside tire because it has the inertia of the spinning inside tire and of the entire drivetrain hitting against it. So pretty often it will break the outside tire free too.

So the end result is the same, get on the power too much in a corner and it's easy to swap ends. And the fix is the same, don't get on the gas too hard in corners. But the misunderstanding can lead to other wrong assumptions, like you need to get off the throttle to unlock the locker. You do need to not spin the tires to get it to unlock, but as long as you aren't spinning tires it will unlock freely.

So is it a common misconception or are the end results the same? The tires only reach the same speed in a turn or coming out of a turn when you get back on the power. Look at it any way you want.

My rear end locks-up when I get on the gas coming out of a turn. And at that point things happen quickly depending on how hard you are into the gas and where you are in a turn. And like I said, my TC probably compounds things...

 

[Nothing Special]

.... My rear end locks-up when I get on the gas coming out of a turn....

No it doesn't. It no longer unlocks when the spinning inside tire speed catches up to the outside tire speed. The difference is subtle, but it's real.

.... And at that point things happen quickly depending on how hard you are into the gas and where you are in a turn. And like I said, my TC probably compounds things...

Yes to all of that. Automatic lockers aren't for everyone. And in my experience (with relatively low powered vehicles), automatic trannies are more forgiving than manuals when it comes to automatic lockers. (It makes a lot of sense that higher power engines and aggressive torque converters would exaggerate the lockers traits more than low power and mild torque converters, but I don't have personal experience there.)

 

[SteveL]

I preferred a spool to all that clunking and locking. At least with the spool I know what's gonna happen every time. This is on my non daily driver. Now that its gonna be on the road more it should be getting the arb soon. Just cleaned the garage so I can get to what I need for the swap.

 

[blubuckaroo]

My reason for not thinking a limited slip (other than a gear-type like the TrueTrac) is an acceptable option doesn't necessarily apply to everyone. But when going around a corner, even if just coasting, if the tire traction isn't good enough to slip the diff, then the tires slip. So when coasting around a corner on ice or snow it can cause you to swap ends.

In my experience there's no acceptable "window" of performance for limited slips. Even the worn out one when I bought my F-250 with 161K miles was still too tight to feel safe in winter driving, but definitely too loose to be helpful when I needed it.

If driving on slippery surfaces isn't a factor, then maybe a limited slip can be a good choice for you. But i certainly don't recommend them.

I'm in agreement with you about the LS being an issue in winter driving. I installed mine while living in SOCAL, then moved to WA. Other than trails, an open rear would be better. I've just learned to coast through turns rather than apply any throttle.
Trails though is a very different thing. On mud, deep snow, boulders, or deep sand, it works great.