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I was cleaning up my rear diff today, and got about 4 pounds of dirt, mud, and sand off of it, along with most of the rust.

But I went to bench drain the fluid, and both bolts are stuck.

I sprayed the living shit out of them with WD40 and PB to no avail.

Any tips? Advice?

Take off the high heels and try again, Lucy.

Bite me, Ethel.

I used a breaker bar, and an impact wrench, and neither worked.

Oh, so you took it out of the car? Or haven't put it in, yet? Is it the new one or the old one?

It is going to be a pain trying to get it loose without it being on the car. See if you can rig something up to make sure it is held down TIGHT, then go at it again. Try a cheater bar on the breaker. And if you get it to move even a 1/8th of a turn, respray it with pb blaster - wait 5 mins, try to get some more rotation. I had to do this to get a nasty spark plug out of one of my wagons (cross-threaded with grit ).

It's the new LSD rear end, sitting on the bench. I wanted to try to get the fluid changed before I installed it, but I guess I'll wait. It's just such a pain to fill the diff with it on the car.

This diff had so much junk and so much shit on it, it was ridiculous. Did you know the diff cover is silver!? You couldn't tell with this thing.

I took off the Vicous LSD sticker though. It kinda got torn up with the wire wheel I was using to clean the thing.

Wait a day or so with the PB, respraying occasionally. Sometimes it takes a while. The other thing is to use a torch to heat it. A propane plumbing torch will do.

Steve

Is a torch going to be OK on aluminum?

Also, the plastic tab on the top of the diff. Is that just a breather tube?

Just gotta put a little man into it

Seriously though, I doubt you'll be able to do it with it sitting on the bench. When the diffs get as old as they are and have been loosened and tighted as much as they have it gets harder and harder to get the plugs out. I'm sure you had a heck of a time doing your current one while it was mounted to the car. Hell even brand new diffs are fairly snug. You're going to have to brace it to something and use force. When I say brace, I mean something as secure as the diff would be in the car. It'd probably just be easier to put it in the car and then put the oil in it.

and yes that's the breather.

Thanks Hardy!

Guess that's what I'll do. The breather thing scared me because I rolled the diff over to clean the bottom of it, and gear oil started leaking everywhere. Whoops.

Forgot the case is alloy. Probably some electrolitic corrosion keeping it in. What about using the breather to drain/refill? Could you rig a vacuum source to it to help it out?

Steve

If worse comes to worse, I'll just unbolt the diff cover and order a new one from the dealer. A stuck drain plug isn't gonna make me not get a rear LSD.

Vikash and I wrestled it out of the car in freezing temperatures, that's not going to waste because of the stupid rear diff cover.

you can still use the torch on aluminum, just be careful with it. The Al conducts heat so fast it is hard to overheat and melt. On the other hand you can mess up the gasket if you go off. Al expands so fast it probably won't take much heat.

a little anti-seize goes a long way for threads like this, too bad the last guy didn't use it.

Before buying a new cover I would install it onto the car and see if you can then get the plug out. The dealer will probably rape you for a new cover. Or pull a cover off another used diff at a JY or something. Anything but buying a new one.

I don't think you can use antiseize on these threads. I believe they're pipe threads that require thread sealant.

I agree with the suggestion to mount the differential to a 3000-lb car to help give you leverage.

Yea, I will have a cover sitting on my bench when I pull my stock diff, so I can swap that if necessary.

Speaking of which, I should drain my stock diff before pulling it. That's probably a contributing factor to the weight of the diff.

It's less than a quart of oil, so I don't think the weight will make too much of a difference. But it could certainly avoid making more of a mess than necessary.

BAC5.2 wrote:Speaking of which, I should drain my stock diff before pulling it. That's probably a contributing factor to the weight of the diff.

There's only .8L in there.

I had the same problem draining/filling my rear diff the 1st time, ended up buying a nice impact gun with 500+ ft*lbs of torque which finally got it loose.... try using a breaker bar and a BFH as well to break the rust.

I think Vikash is correct with the pipe threads, I use teflon tape on the threads of the plugs, and i don't tighten them to anywhere close to what they were originally

I had a hell of a time getting the drain one open on mine. Impact gun just kept spinning inside and the breaker bar "square" didn't seem to work as well as the ratchet.

I finally got it out, but it was a major pain in the arse.

If you've still got your old one, can't you just swap the covers? Or do you have a buyer for it already?

Edit: NM... Missed the middle of the thread...

I think I'm going to tear into my old one, and see about phantom gripping it or something. I don't think an open 3.9 diff would be worth a whole lot.