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crawlingno5
06-12-2002, 11:48 PM
pardon my ignorance..BUT

I am looking at my 4-wheeler magazine, and at Randy's Ring and Pinion ad, theres a ad for mini spools and full spools? whats the difference? and then theres positrac and lockers, again, whats the difference?

bburris
06-13-2002, 12:01 AM
mini spools go in your stock carrier, like a drop-in style locker

full spools are replacement carriers that your gears bolt to

crawlingno5
06-13-2002, 12:27 AM
so then i guess its safe to assume mini's are weaker..

Then whats the difference between a spool and a locker?

StevenAg03
06-13-2002, 12:50 AM
i wouldnt go so far as to say that a mini spool is weaker then a full spool. i personally dont see the point in buying a mini spool, unless you already paid to have the gears set and dont want to do it again.

to answer your second question....whats the difference between spools and lockers.

Spools, in effect, lock both axle shafts together. once a spool is installed the axle shafts will always spin in unison. this is why when you turn with a spool the inside tire shirps like a bird.

lockers on the other hand are supposed to allow one of the tires to spin faster then the other when not under power(this is in theory anyway). so if you wanted to make a turn with a locker, it would allow the inside tire to spin a little bit slower. that is why if you have a detroit or something of the like...the engage and dis engage in corners....also known as popping...

positracts and limited slip differentials(LSD's) are kind of querky(sp?) sometimes they hold good other times they dont. LSD's have clutches in the carrier and if one wheel is in a big bind then it will probably only send power to the free wheel. you can never rely on a posi or LSD to keep the tire locked together.

any more questions....:D

bburris
06-13-2002, 12:52 AM
yeah, everyone has told me minis are weaker and more prone to failure than a full spool

a spool always sends power to both tires, while a locker differentiates (theoretically) when your axle isn't under power

I'm sure there are better answers, and plenty of people can and will chime in, but that's the basics for ya

mark
06-13-2002, 06:55 AM
With a mini spool, the weak link is either the spool or the carrier. So if an axle has a carrier know to be weak, say a Dana 35, then a full spool would be stronger because it eliminates the weak link of the carrier. In an axle with a strong carrier, say a GM 14 bolt, the carrier is plenty strong, so there would be little difference in the ultimate strength between a full and mini spool.

I would chose between the two based on convenience, if strength is not an issue with your axle. The mini is a drop in and can be replaced with conventional spider gears if you ever want an open diff again. A full spool is obviously more permanent.

Other diffs:

An open diff infinitely divides power between the two wheels. The amount of torque varies directly with the wheel’s speed. So as one wheel speeds up faster than the other, more torque goes to that side. This happens when cornering or when the power to a wheel exceeds the traction available. The later happens off road frequently. That’s why open diff = bad.

A locker lets one wheel spin faster than the other, but never slower. So when you go around a corner, the outside wheel wants to spin faster than the inside wheel. The difference in torque between the two wheels unlocks the locker and allows the differential wheel speeds. The problem is that when this happens, all of the engine's power is delivered to the inside wheel causing handling quirks, especially at low speeds.

LSD’s (limited slip differentials) and posi’s (there is no difference between the two) act more like open diffs as power is divided between the wheels. But the amount of bias towards one side or the other is limited by gears or clutches. These types of diffs either sense the difference in speed or torque between the wheels and limit that difference within the parameters of their design. The more difference they allow, the more streetable they are but the worse they do off road. There are some that will fully lock up, but that requires a significant amount of wheel spinning. Most will never fully lock up, so if you lift a tire, you are out of luck. But its better than an open diff.

Selectable lockers are simply differentials that can be fully locked on command. They either allow differential action or they act as a spool. An ARB for example is an open diff than can be made to act as a spool. The Jeep Wrangler Rubicon has lockers that normally are limited slips but can be locked up like a spool as well. I’d like to see a selectable locker that is normally a limited slip, but when locked, acts like a Detroit locker rather than a spool.

Hope the explanation helps.

-Mark