Lockers are expensive and open diffs suck-a-duck off-road, so for chump-cheap traction, it’s hard to beat the age-old method of simply welding up your differential spider gears to create a mini spool. But is a welded diff for you? Well, in our best Jeff Foxworthy voice: If your welds are weaker than year-old bubblegum stuck under a table, a welded diff might not be for you. If you want your Jeep to have street manners rivaling a British butler, a welded diff might not be for you. If your axleshafts are as spindly as a steroid freak’s legs and your tires as huge as his biceps, a welded diff might not be for you. If you’re as good a mechanic as Tiger Woods is a faithful husband, a welded diff might not be for you.
There are a couple ways to...
There are a couple ways to weld up your spiders. You can tack-weld them inside the case and then remove them to be fully welded. However, there’s a slight chance the heat from welding could cause them to cock, making reassembly difficult. We normally just weld the gears together inside the case, making sure to get as much weld coverage as our MIG gun will allow. Don’t forget: If you’ve got C-clip axleshafts, don’t weld the cross pin to the gears. It may also be a good idea to protect the cross pin with some aluminum foil to keep any large weld boogers from sticking that would prevent the pin from being removed. Otherwise, you won’t be able to get your C-clips back on your axleshafts.
So with all that said, we think you can guess what we’re getting at. Welded diffs can offer cheap traction, but you should only take on the project if stuff like disassembling your axle and laying down some clean, well-penetrating welds is in your repertoire. Likewise, since you’ll be creating a spool, keep in mind your street driving will be compromised to some degree with chirping rear tires around corners and a slightly diminished turning radius. The welded diff will also put added strain on your axleshafts, so keep your tire size within limits if shaft survivability is important to you. Finally, we really don’t recommend welding your front diff. Keep the welded diffs out back and pop for a real auto or selectable locker up front.
While you can technically...
While you can technically weld up your spider gears with the diff still in the axlehousing, you’ll be able to achieve much better welds if you pull the differential out. Begin by draining the gear lube and removing the shafts. If your axle is a C-clip design, remove the cross pin, push the shafts inward, and remove the C-clips. Non-C-clip axles are held in place with retaining plates with four or six nuts per side.
Most C-clip axleshafts will...
Most C-clip axleshafts will come out of the housing easily. Non-C-clip axles usually require a bit of persuasion. You can use a slide hammer if you have one, but we usually just put the brake drum over the lug studs, thread on a couple lug nuts, and give it a few pulls to free the shaft. If you’re running older two-piece shafts on your Dana 41, 44, or Model 20 you may want to rethink welding your diff, as the shafts will almost always spin in the hub with any real off-road use once the diff is locked up or welded.
With the shafts removed, use...
With the shafts removed, use a centerpunch to mark the diff bearing caps so you can put them on the same way. It’s important they go back on not only on the same side (left or right) but in the same orientation (top-to-bottom). With the diff still in the housing, give it a good pre-spray with brake parts cleaner to get most of the gear lube off.
Yea, it’s a front axle, but...
Yea, it’s a front axle, but for illustrative purposes, unless your carrier bearings are completely worn you’ll need a couple large prybars to get the diff to come free. Be careful what you pry against—you don’t want to chip the ring gear, damage the carrier bearings, or gall the diff cover mating surface. You also want to be careful the diff doesn’t drop on the ground during the removal process.
With the carrier on the workbench,...
With the carrier on the workbench, remove the ring gear bolts and use a deadblow hammer or a brass drift to drive the ring gear off the carrier. You don’t want to get any weld splatter on the gear teeth, as it can quickly destroy your axle gears. Thoroughly clean the diff and spider gears of any and all grease in a parts washer if you have access to one. If not, plan on burning through at least two cans of brake cleaner to get the job done. Don’t forget to use red Loctite when reassembling the ring gear to the carrier.
All it takes is one molten...
All it takes is one molten dingle ball to ruin your carrier bearings. A couple heavy layers of aluminum foil will go a long way in protecting your bearings and minimize any cleanup. You can use a MIG, TIG, or arc welder. We’ve welded the spider gears to the case in the past, but we just did it butch-style with no pre-heating or cooling cycle on the cast steel. If you know how to properly weld to cast steel, you probably don’t need any information from us on this subject. Keep in mind that you can weaken the carrier by welding on it, so if you don’t know what you’re doing it may be best to keep your welds on the steel spider gears only.