Racefriv Fab: Welding Differentials

I've always loved fabricating things, it's one of my favorite things to do and its actually rare that I get to break out the welder but lately I've been trying to change that. When my good bud JJ asked me to weld his diff for his beast V8 S13 build I went by, picked it up and got to the melting.  While I was at it I took some pictures to share with everyone. So click read more to check out my welding setup and what it looks like to weld a diff.

 Full Disclosure: I am not a master welder by any means, nor do I claim to be an professional diff welder, this is how I do it, weld your drivetrain parts at your own risk.


Note: Drifters weld diffs as a cheap reliable way to keep the rear wheels locked and spinning at the same rate, yes it sucks at low speeds and yes its awesome to drift with. For any further info please refer to google.

OK. First let me show you guys what I'm working with here, so you know what you might need to get started on your own projects and maybe how much you would need to invest to get welding.

Right now my setup is sort of a mix of a couple different welders, one being my old Lincoln Electric handy-MIG that died on me and the second one being the pro-core 100 that my buds let me have for pretty much free. You can get a pro core welder for $300 right now but they only come in Flux welding capabilities which is why I said mine is a mix, as I used some parts from my old handy MIG to make this welder work with Gas. Most welders that run flux can be converted to use gas pretty easily you just need to find the right parts.  

The Pro-core 100 here runs off of a 110v plug and needs at least a 20amp breaker to work right. That last bit is pretty important. You need to run your welder of a plug that has a high breaker amperage and you need a extension cable that can handle it. Your typical run of the mill cheap orange cord is going to get hot and fail. I use a large gauge cable from Lowes and plug into my washing machine plug that I know has a dedicated 35 amp breaker.   Also yes 110v is high enough to weld most anything car related I've discovered, 220v would be great but they're pricey and you don't need one unless you're doing some major stuff.  

Like I said before I converted this one to Gas, to be a true MIG. Gas is a million times better to work with than flux, my honest opinion is, even if you're just starting to learn, go with gas as it lays down welds so much nicer and is much stronger.  In addition to the welder, the tank, and my sweet harbor freight cart you're going to need a few more things.



A lot of beginner welders come with this awful mask that you hold over your face while you weld, go ahead and throw that in the trash and get your self a decent auto-tinting helmet, there not that expensive and it makes life so much easier, also good welding gloves so you dont burn your self, and a good stainless brush to clean things with.



Also that new welder is going to come with a super weak ground clamp, go ahead and throw that in the trash as well and pick up a nice big ground clamp with copper teeth like this, your welds will improve significantly with a better ground. Everything else like tips, wire, etc.. you'll just have to google on your own and see what works best for your application.

Alright now off to some actual welding!

Heres the diff of choice, an S13 open diff, if your going to weld a diff start with an open one, there is way more space to work with compared to a VLSD and of course you'd be an idiot to weld a LSD.

You can weld a diff installed in the car sometimes but that's a giant pain in the ass, I only weld them taken out so I can really concentrate on the weld. I usually pick it up on a couple of jack stands like this and get in my office  garage chair and sit down to work on it. I need to note here that I cleaned the shit out of this diff before I started to weld on it, Don't use brake cleaner as it can vaporize under welding arc and give you nerve damage if you inhale it.  I usually use a mix of purple power and water.  So be very careful with fumes while doing this, I usually put a fan behind me so all the fumes are pushed away from my face. 

The object of all this is to weld those teeth on the inside of that box together so they don't rotate anymore, essentially locking the axles forever together.

Once Im all set up I go ahead and cut out these little plates with a cutting wheel. Today Im using 1/4 " plate steel, the good stuff. This is called "plating" When you hear people mention "was it plated?" this is what they're talking about.

The plates should fit inside the gears like so.... and we're going to weld them in later.

Ok so we know the plates fit lets get to some welding. I like to cover some of the diff with rags to keep the slag from sticking to important things like the ring gear. The down side to welding diffs in this position is that the slag tends to fall down to the ring a pinion gear and you have to turn the diff upside down every now and then to shake it out, make sure everything still turns smoothly and there is no slag binding the ring and pinion gear which could lead to the diff failing.

Once you feel ready to hit the diff, go for the corners firs,t welding at least two blades from every corner together.

Get down there all deep like.... get every corner on both the top and bottom, meaning weld all the corners then rotate it over to the other side and weld all those corners.

You should have something like this now, hopefully with a little less slag bits.

From above it should look this this now.

Then throw those plates you made in there and weld those in around every side.



Hopefully it came out like the photo below. Its a little tricky to do this right, your going to need some practice before it looks decent.

Now you have a diff that hopefully never slips or breaks ever again. With a 1/4" plate welded in there JJ should be breaking axles or wheel studs before this breaks.  When your done with welding her up, dont forget to clean it extremely well and get all the tiny bits of metal out of there as diffs and bits of metal dont get along. I always recommend that you change the diff fluid after 100 miles or one drift event after welding a diff to make sure everything that is going to knock loose is out and the diff is clean and happy.

So there you go, thats welding a diff. A simple process thats easy to do but hard to master. I can't wait to throw this on JJ's car to give it some hell. This is about the 5th diff I've welded and by far the strongest one, so hopefully it doesn't let him down. Also If any body out there is local to ATL and needs a diff welded hit us up and bring it by the racefriv house and I'll hook you up. 

Till next time everyone -Ish