You're making too much work for yourself for just a torn boot. If you're not wanting to spend the money to fix it why bother replacing a boot? You're still going to have to clean out and repack the joint with fresh grease or it's just a waste of time. Plus you need band clamping pliers. At that point you've already done more work than you would have just replacing the joint altogether.

Slap a split boot kit on there, drive it until the cv joint/axle or hub is worn out and then replace them both at the same time. You can get them both with better quality and cheaper at rockauto than the junk at the local parts store. $2 or $3 hundred at most.

If you're absolutely determined, just buy a heavy duty 1 inch drive impact. It'll come in handy for the rest of your life.

If you don't want to spend the money then:

In addition to all the bs everyone else has said (including knocking the stake out), torch, penetrant, etc., put a cheater pipe on the end of the biggest breaker bar you can find, lift the vehicle up about as far as the jack will go, set the bar so that the handle is against the ground and lower the vehicle until something busts.

Be sure to place a block under the lift point that's tall enough to keep anything from scraping the ground when the vehicle comes down.

And that's your litmus test. If the breaker bar pops before the nut then just buy a decent impact or the replacement parts.

Source: former mechanic.

Edit: Oh, if you can get a cutting tool in there, you can also cut a wedge out of the nut, use an air hammer with chisel tip. It works surprisingly well.

You already got all the good tips (big ol chunk of pipe as breaker bar extension being the best), just here to say I'm rooting for you lol. Keep us posted!

Medium weight atomic weaponry should take care of that.

You're not the first to turn to the internet when trying to bust a nut.

Paraffin wax can work surprisingly well if you heat the nut and melt the wax against it. Capillary action pulls it into the threads and has accomplished some amazing feats for me.

Heat again, and add an extension pipe to the 24" breaker bar for even more leverage.

And remember, you're heating to make the part expand, so don't heat the bolt, heat the nut/threaded socket

Just wait for no nut November

To start with, that is a stake nut. You can see on the bottom about 5oclock position the edge of the nut is dented in, that locks it to a keyway on the cv axle shaft. There's not much left of that ofc but it's still holding something in place and not helping. Usually have to grind that off or pry the staked part out using a screwdriver.

I borrow a 3/4" anvil high-flow pneumatic impact wrench for stuck axle nuts. On clean west coast cars I can use my normal impacts but anything with the slightest modicum of rust needs the most torque you can throw at it. Use a high quality black 6pt impact socket to have the highest chances of removal without rounding the nut.

Something else you can do is put a heavy duty breaker bar on it that is longer than your tire, then drive the car backwards/forwards to apply torque. This usually breaks most breaker bars though, unless you get a 3/4 or 1" anvil.

Honestly at this stage I am assuming the end of that CV axle is cooked. I have very little hope that the threads will be usable once it comes off- and seeing as the CV axle holds the wheel bearing together, its not something I would chance. You can get aftermarket cv axles that usually last maybe 50k for under $80 US, which they suck but it is no 500CAD that you probably got quoted for an OE axle.

If that isn't an option you could leave the outboard joint alone and disassemble it from the inside half by removing the knuckle from the car (disconnecting brake caliper, control arms, and the shock/strut) and sliding the axle out of the trans. Most CV axles can disassemble from one or both sides for a boot replacement.

If the nut totally fucks off and you are SOL on the axle, drilling out the axle center in progressively larger holes until the threads are gone and the outer piece falls off might be your best bet.

You need to clean the crud off the axle end, soak the nut in Aerocroil, then heat it cherry red. Then put a breaker bar on it.

Note that I'm going off the level of crud currently shown on the threads.

Maybe you can find some sort of cap on there? To hold in penetrating lube? Fill it up nd let it soak for a couple of days.

Ideally you have on oxyacetelene torch and a 1" impact that will separate and vibrate it into submission. Otherwise you could get a functional propane torch, heat up the outside of the nut, and hit it with the biggest wrench and cheater pipe you can find. Like 6+ ft. long cheater pipe (that thing is rusted to hell).

Soak it in Penetrant Blaster for like, at least two hours. Then try the breaker bar and impact again. If it still doesn't move, your could try using an air chisel on the edge, trying to spin it loose with the air chisel. The last resort air chisel has never failed me, but you do need to be careful not to damage threads or surrounding parts.

Also, double check the manual if the bolt is left hand thread or right hand thread. Don't want to tighten the bolt and snap it thinking you are loosening it.

At least half a dozen years? Like 6 years? I usually don't remove hubs in 6 years :)

Oxy-acetylene. It can't be tight if it's liquid.

I'd probably start by using a punch and a heavy hammer to hit the edges of the nut around its circumference in the hope of breaking up the rust enough that it turns with one of the methods you already have. If that doesn't work, escalate. A length pipe over the breaker bar handle to extend it is the cheapest escalation, though you increase the chances of breaking the socket or the bar.

A sufficiently powerful impact tool will almost certainly do it, but if you have to buy it new, you might end up 500 CAD on this job anyway.

Is it possible that the nut is reverse threaded? Ie, clockwise to undo it?

One of those induction heaters might work if the coil fits there but you probably would've already tried that if you had one. They're not exactly cheap either.

Personally I'd just drill the nut and split it.

The nut still looks like a nut, so all is not lost. It's just stuck.

Here's what you do:

1. Whip up a 50/50 mix of ATF and acetone. It will separate after a time, so shake it vigorously before you use it. It's the ultimate penetrant solution.
2. Take that mix and soak the axle stub and nut with it. Get the back of the nut, too, where it meets the hub. Don't worry about making a mess. You want this to come off, right?
3. Wait 24-48 hours. Reapply ATF/acetone mix multiple times while you wait, and periodically smack the stub with a hammer for good measure. You want the penetrant in every nook and cranny it can reach.
4. When you're ready to remove the axle again, make sure your air compressor is fully charged and hit it hard with the impact gun. Hold the trigger until the compressor kicks on again, then hold it some more. Repeat as needed.
5. If it still hasn't budged, bust out the torch again (or borrow one) and heat that fucker until it's cherry red. Hit it with the impact gun while it's still glowing.

Repeat this process until it comes off. Chances are it'll pop loose by step 4. But keep that torch handy. Yes, it's more-or-less what you've already done, and it will come off if you keep at it.

Add a 6' iron pipe to that breaker bar. Borrow a torch without fuel issues. Prey to the grease gods

Any chance you have a neighbor that might have a serious impact driver

A better impact. I recently had to remove the bolt from the end of a crankshaft. I borrowed an air impact from a neighbor (a mastercraft) and it did nothing. When I took it back he said "I've got another one do you want to try it?" The second one undid the bolt like it was only finger tight!

I think the mastercraft was rated for ~300ftlb, the 2nd one about 600.

I’ve heard that 50/50 acetone and ATF does wonderful things.

That and one of those Milwaukee impacts with enough torque to make the earth spin backwards.

Bunch of good suggestions in the comments. I'd also take a wire brush to any exposed threads and knock some of that junk off.

If all else fails, cut the nut (as mentioned by others, a cutting torch is useful here).

But these days they usually don't seize beyond the ability of a penetrant and a cheater bar.

Had a stuck nut once that wouldn't budge even with penetrating oil and a bigass 3/4 drive impact.
Ended up needing a 10ft pipe on the breaker bar and the weight of 2 grown ups at the end of it.
The 10ft bar doubles as a security feature because when it finally moved it sounded like a bomb went off and I was glad to be that far away. Good luck.

and this car isn’t really worth the $500 CAD for an axle replacement

Then I'd put a split boot on it and rock it till it clatters.

Looks wet. Presume you used PB blaster?

I would just PB and sit on the impact wrench until it comes loose. But I’m not a pro by any means.

What’s the year, make and model of the vehicle? Maybe it doesn’t come off like that?

Maybe it can already come off but the hub is rusted to the plate in which case you can drill a bolt into that hole on the right side in the picture and try to pry it off.