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Welding differential side gears is a method of creating a locker that allows for far greater traction than an open differential (common on stock vehicles) or even a limited slip differential (commonly known as a posi traction device).

Although welded diffs may not be the ultimate way to lock your differential, it can be the cheapest if you know how to the work yourself or know someone who can do it for you cheap or free.

There are different ways to weld differentials to create a locker. Some are created by welding the side gears to the spider gears. This eliminates the differentiation of the open differential as the spider gears and side gears no longer move independently but as a single unit. Another way, which may be considered stronger by some, is to weld the spider and side gears together, and then weld them to the differential case (some people even had pieces of metal to this process in order to make a more solid assembly weld). These two examples do not allow any differentiation at all between the two axle shafts, and consequently the wheels and tires.

In the example pictured here, you will see that only some of the valleys in the side gear teeth are filled in with filler metal from a MIG welder. This is to allow a small amount of differentiation between the two wheels on that axle assembly. This can make it a little easier to steer in tight situations on the trail. It also makes it easier to unlock manual lockout hubs. A fully welded diff will often bind up the drive-train making it difficult to unlock the hubs.

The procedure pictured here is being performed on an '87 Suzuki Samurai rear third member. First the third member is removed from the axle assembly housing (first removing the axle shafts to allow removal of the third member). Once the third member is on the bench, it is marked with a punch so that the parts go back in their original orientation (this is very important).

Once disassembled, the side gears are cleaned thoroughly in solvent. Now they are ready to be welded. The choice of welding process is primarily based on what is available at the time. Welded diffs are often referred to as Lincoln Lockers because they were commonly welded with Lincoln stick welders in the past. These days a lot of 4wheelers have MIG welders and they work just fine. You could even use TIG if you have that available and feel comfortable with that process.

Once the appropriate pattern and number of valleys to be welded have been determined for any particular application, the welding commences. In this case our secret tech monkey filled the gaps to the top of the teeth ridges, then ground the welds flush with an angle grinder. He reassembled the carrier and third member, then checked the ring and pinion backlash and contact pattern.

With the third reinstalled in the Samurai, I was able to traverse many new obstacles with the added traction. With the welded rear, I experienced wheel chirping on pavement, and accelerated tire wear. With an open diff I ran 20-22psi in the tires, but in order to minimize the chirping and tire wear effects of the locker I started running 30psi.

Ideally you would want to install a full carrier replacing locker such as a Detroit or ARB locker or even a spool to get the most strength out of the unit. On the other-hand, if you don't have a lot of money, and don't mind the possibility of breaking the carrier or related parts (nice to have spares) then this is a cheap way to go.

Note: The pattern welded on the Samurai side gears are in a double wing butterfly pattern because the Samurai differential uses four spider gears. Click here to see a single wing pattern for a Dana 30 which uses two spider gears.

Second side gear installed