Like the title says. I know what LSD's do. they typically limit slip to the unloaded wheel to aid in tracktion. Open diffs I'm quite familiar with. I know full spools basically are a 100% connection between the axles. So what are mini-spools and lockers? How do they work? How do they take street driving? turning in general?
Lockers use some sort of mechanical locking of the dif. Air, electric and just a manual cable are the 3 common types. A mini spool just replaces the spider gears and is cheaper than a regular spool. aka it is like a lincoln locker but not hack.
Some spools will not lock up immediately and are turning friendly most are not. A locker is either 100% locked or 100% open and you can choose when so turning and street driving is fine.
You can get away with running a spool in the front of a 4x4 if it has manual hubs since it wont have power most of the time and you can lock only 1 hub and it will act like an open dif.
A spool never unlocks, they all handle the same as a welded diff. Both wheels turn at exactly the same speed all the time.
A locker unlocks with a certain amount of turning force if it's an auto locker, or when selected if it's some kind of manual locker.
An LSD limits slip between the wheels somehow (generally without fully locking up, and sometimes without fully unlocking), there are many different kinds of LSDs.
Keep in mind:
Open diff = 50% of engine torque max to each axle.
Spool = 100% of engine torque max to each axle.
A spool can double the torque load on your axles.
This is in a 12-bolt gm truck axle. Short wheelbase and all that. One of those lockers just really looks like an easy button which makes me think I'm missing something
In reply to Bobzilla:
if its for a drag car a spool is fine. if you want to street drive it just get a mech locker or an lsd
In reply to Bobzilla:
That's what is commonly referred to as a "lunchbox locker." I've thought pretty hard about putting one in my XJ, but from what I understand they can be a bit unwieldy on the street. Pretty much any time you're putting torque through it, it's going to want to lock, so adaptations to your driving style, like coasting through turns, are required.
On the plus side, mini spools and lunchbox lockers can be installed without swapping the carrier, so install is much more diy friendly and cheaper.
I put a Detroit Tru-Trac in the 12-bolt in my C10. Mainly because I wanted a limited slip, but also because I thought it would be the least unpleasant in a Canadian winter.
I flat-out LOVE the thing, and would do it again in a heart beat (non-intended Chevy reference).
Anecdotally, lunchbox lockers are far easier to live with when installed in a stick-shift rig instead of an automatic. Reason being that you can just put the clutch in to coast into parking spots and such. I had one in my 87 Toyota 4x4 and didn't think it was that bad. It would make a racket around corners and occasionally bang and such but the truck was sorta a beater so I didn't mind.
Robbie wrote: Keep in mind: Open diff = 50% of engine torque max to each axle. Spool = 100% of engine torque max to each axle. A spool can double the torque load on your axles.
This is kind of incorrect... An open diff will always divide torque equally, so it will always be 50%. If one wheel is spinning, it isn't transmitting much torque, so the other wheel will also transmit that same minimal amount of torque.
A welded diff can transmit over 100% of the torque. Imagine being in a tight enough corner that the outside wheel is being dragged along. That force gets transmitted to the other wheel. So you may have negative 30% on the outside wheel and 130% on the inside wheel, for example. This is why spools/welded diffs like to break axles, you can very easily load the axles way harder than the engine ever could.
I want to do this to my Montero.
I pput an Eaton G80 locker in my Colorado and it works very well. It's not actually a locker, but a limited slip. They Don"t have the best reputation, but it's not deserved, there are millions of them out there that will never have problems
I've said it here before: I had a mini-spool in the Dana 44 in my XJ Cherokee for a lot of miles and didn't have a single issue with driving including several tight corners every day.
Didn't notice increased tire wear either. In the crazy snowstorms I drove it thorough it was amazingly easy. Snow-induced understeer was easily corrected with the gas pedal.
(Off road was night-and-day better)
The plus side is this thing will never see snow. But it will see a lot of autox and maybe a few track days down the road. LSD or mini spool better for that?
Tight turning in this is already atrocious. I swear our crew cab has a better turning radius and it's 4' longer.
That depends on chassis. The RX-7 didn't seem to make a difference with a leded diff or a limited slip. It has better turn-in with an open diff of course. Probably a Torsen would be the best of both worlds, an open diff that can put power down. Or a real Locker, which isn't a diff at all but a kind of spool that still allows one wheel to freewheel. Can't wait to try that out.
I tried autocrossing my VW with the center and rear diffs locked. That lasted about half a run before I disengaged them on a straightaway. Bad bad bad bad 
Bobzilla wrote: The plus side is this thing will never see snow. But it will see a lot of autox and maybe a few track days down the road. LSD or mini spool better for that? Tight turning in this is already atrocious. I swear our crew cab has a better turning radius and it's 4' longer.
You need an LSD. The truck on your wide tires isn't going to like turning with a spool.
I'm locked tight on the datsun and a little car with short wheelbase and 205's doesn't care and turns fine. You have a short wheelbase truck, with the same wheelbase as a car that's a land yacht. The eaton limited slip in my impala is nice. You're going to get sideways the first few dozen times you apply heavy throttle mid corner, but it'll make you smile then you will get used to it and only get sideways for fun
Doesn't the Roadkill Muscle Truck run a spool? They've autocrossed that thing before 
Seriously though, for what you can usually get a mini spool for and the effort to install one (or reverse it later), worth a try at least. If nothing else, I bet it would be a ton of fun.
Id want an lsd or a locker in your application. A good friend ran a mini spool on the street for 3 years in a 3800lb ext cab s10 and it never grenaded but it did manage to wear everything to pure slop and twist the axle ends. With more power and the desire to turn i dont think mini spool is the proper answer.
With a spool, you steer with the gas pedal.
If you have enough power you won't understeer!
If it's a GM truck you're building, you can probably do the Eaton for peanuts, and there are mods you can DIY to prevent them from unlocking at speed.
ebonyandivory wrote: With a spool, you steer with the gas pedal. If you have enough power you won't understeer!
It's the creepiest thing. It isn't "the back end slides out under power", it's "the front end dives to the inside of the corner like it was yanked by a cord, under power".
Just don't lift. Adding power is always your friend.
Knurled wrote:ebonyandivory wrote: With a spool, you steer with the gas pedal. If you have enough power you won't understeer!It's the creepiest thing. It isn't "the back end slides out under power", it's "the front end dives to the inside of the corner like it was yanked by a cord, under power". Just don't lift. Adding power is always your friend.
A 4 link in the rear that has some roll steer can cause the same effect even without sliding the rear end at all. Add power, weight shifts to the rear, suspension rolls outwards a bit more, car tightens its line. In that situation, it's actually helpful to grip but it feels kinda weird at first.
My basic impression of spool or welded diff on the street is, if you don't have a bunch of tire traction back there, it will mostly be ok. If you have a ton of tire traction back there it's going to wear stuff and break stuff and piss you off.
My Montero has 235s that are skinny and void-filled and SO ready for lockage.
I'm pretty opinionated on this subject; any series where the car builder has a choice they use a LSD. The only exception being Sprint Cars, Drag cars, Superspeedways.
There's a reason F1 cars have them (yes they are adjustable). When using lockers and spools and or welded diffs, you end up with set up compromises.
My F500 uses a Kart axle and if there is one rule change for the class I'd make it would be the allowance of a diff. Locked or locker diffs on autocross or road race cars suck. (Not that I have an opinion on this)
Very often a car is faster with a welded diff than an open one but they are still slower than if equipped with a proper LSD
Install a LSD and be done with it. Yes they can be rather expensive on some vehicles. All of this is my opinion of course but the choice to not use one always seems to be driven by price. Granted the type of LSD matters as well.
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