Lincoln Locker and Fozzy Locker Lockers, Limited Slips, Differentials and the sport of Offroading. An Overview of Standard Carriers, Positraction & Limited Slips, Locking Differentials, Spools and Mini-Spools

Lincoln Lockers

A Lincoln Locker is a homemade spool created by welding the OEM carrier so that the spider gears no longer turn.  This is known as a "Lincoln Locker" by adopting the name of a popular brand of welding equipment made by Lincoln.  This method can vary anywhere from relatively strong to weak and brittle depending on the strength of the carrier being used and the quality of the welds and where the welds are placed.  In many cases welds thought to be strong are not and break under the stress.   Lincoln Lockers merely replace the minimal cost of a mini spool which has the same net results in traction but can be removed later and the spider gears put back in place.

Fozzy Locker

Fozzy locker is a twist to the standard Lincoln Locker.  Apparently made popular by a guy named Fozzy.  The Fozzy Locker is a cheap, removable version of the "Lincoln Locker" where the teeth of the side gears of the spider gear set are partially filled by welding material.

Some people who have created a Fozzy locker weld up the valley between 2 adjacent teeth on the side gears as pictured to the right.  Welds are done 180° apart. Both side gears are done this way.  The valley between the teeth are then fill until flush with the top of the teeth and ground flat.  Some people say there are a couple advantages to the fozzy Locker.  By only doing the two valleys it allows the side gears to still rotate partially before locking.  The gears that are being welded are the same gears that are replaced when a drop in a "lunch box locker" so if it doesn't work out as you hoped or if you damage a side gear, it can be replaced by one of several drop-in lockers such as a Lock Rite or a Detroit EZ Locker.  Ultimately this type of locker will not ratchet (disengage) around corners as a an automatic locker would would and can be hard on the stock open carrier especially when a wheel spins and hits the weld placing a large amount of shock on the stock carrier.

Differential Differences
Overview of Standard Carriers, Positraction & Limited Slips, Locking Differentials, Spools and Mini-Spools

Teralow Installation in a Dana 20 Transfercase
Installing Tera-Low gears for better crawling

Other Sources:

Jake's Take on the "Lincoln locker", named after the Lincoln Welding Co.

Fabbing a Fozzy Locker
A Fozzy Locker is a form of welded differential where a bead of metal is laid down between the two opposite teeth of each spider gear in a differential.

Fozzy Locker vs. The Welded Lincoln Locker Discussion

Fozzy Lockers are basically a Lincoln Locker (welded spider gears) with a twist.

Fozzy Locker in a Samari

Lincoln Lock or mini-spool discussion on Binder Bulletin Forums
I would recommend doing the fozzy locker. I have done a few now and they have worked good.