Grrrr....ran into another challenge last night when trying to remove the carrier assembly out of my '90 Miata. Yet another nut issue. But this time I didn't strip it. I got some great help from Keith (thanks dude!) and someone on the Miata board, but I also want to see if anyone has encountered a situation like this and had a GRM solution.
The Miata's diff is attached to a powerplant frame (PPF). It's got two long bolts going through it. I was trying to remove the long bolts last night. One started coming out fine. But the other has a smooth round nut on the top. I guess the nut is supposed to stay in place when you turn the bolt. But in my case, it broke loose. So the nut is spinning with the bolt, and I'm getting nowhere. It's a very tight fit where the nut is, so I can't get anything in there right now. If I drop the whole PPF down, I'll be able to get better access to it. Keith suggested vice grips, which I'll definitely try (by the way Keith, my feeble brain will eventually figure out where the spacer and sleeves are 
), but not sure I'll be able to get a hard enough grip on it to turn the bolt, the nut is really smooth. Do you think I could hammer on a nut extracting socket to hold it if the vice grips won't work? Here's a picture of the area. It's not my car, but it looks the same. You can see the bolt head at the very far right of the picture. The nut is all the way on top. 
Experience has taught that for big/under car/corroded stuff like this, spending a little extra time on the front end beats a metric sh1t ton of working around and problem solving on the back end.
If there's a reasonable chance something may put up resistance I'll get it hot with a MAPP torch and apply KROIL. If I'm doing other stuff I may heat and apply more than once. The first force I'll apply will be w/ as much overkill as I can muster. Always a good fitting 6 point impact socket, and either a 1/2" impact gun w/ the compressor just having cycled, or a big-ass breaker bar.
I've had the PPF off my Miata once and found it to be both counterintuitive and a huge pain in the ass. The re-use of a bolt as an extractor and baffling mechanical concept we the issue.
And I'm a really good mechanic, and design and build complex mechanisms for a living.
There's a load of DIY pictorials about how to do this.
PPF removal for example
I've been looking around for good write ups, that one is pretty good. Most of what I found were about swapping the guts inside or going to a different rear, not much about actually pulling the carrier out.
I sprayed it with PB before I tried turning it. I don't have a torch, or impact wrench, just a breaker bar. That's stuff I want to add to my tool collection as I get more skill (and money). So now I've got the sleeve (nut) spinning with the bolt. I'll head to HF at lunch to get a good set of vice grips, as the one I have is junk. If that doesn't work...
Don49
Reader
3/1/12 11:44 a.m.
Before you put the vise grips on take a file and put opposing flats on the round nut.
This will allow you better grip and a higher chance of success.
