Hey ya’ll, I hope you can help. I’m new to fixing my own vehicle and I recently bought a van that is giving me a crash course.
You see, it has a bad rear U-Joint. It shudders at high speeds, squeaks at low speeds, and clanks whenever I put it into gear. I’ve also crawled underneath and confirmed this by shaking the dickens out of it while it was in neutral. I bought a Chilton’s and I’ve also read pages upon pages on the internet on U-Joints and driveshafts. I bought a set of new U-Joints, I can see exactly where they go, and know exactly what I have to do to get to them. I’m all ready.
Except I can not, for the life of me, get two of the 4 bolts off to remove the drive shaft. This van’s pretty old (1993 Ford Econoline) so they’re rusted up pretty badly. One came off with the wrench, another with the help of vice grips and a hammer after I stripped the head, but #3 (which has, along with #4, a stripped head) is becoming soft and misshapen with the vice grips and becoming impossible to work with.
So, I need tips on getting those suckers off. I would really like to avoid a mechanic.
A bit more info:
1)I’ve tried WD-40 to no avail
2)I bought a propane torch based on someone’s advice, but I’m a bit hesitant to heat it too much because I’m afraid some of the residual grease will ignite or perhaps the heat will work back into that big things in the middle of the rear axle that I know is full of some sort of lube oil (I warned you I’m new to this!) Am I being too paranoid?
3)I only have a basic socket wrench kit. Picture a $75 Craftsman set. I am willing to buy a few specialty tools if they’re not exorbitantly expensive.
Sure hope you guys can help me. That way when I get it fixed I can come back to ask about a drain in my electrical system. 
Thanks tons!
Angle grinder with a cutting blade. Cut just off the base of the bolt or nut head to ensure you don’t damage the propshaft yolk.
A cold chisel and hammer will finish the job.
Don’t be afraid to use the heat. Sure! There’s going to be smoke and maybe a small fire? But be prepared for that. Welcome to the world of vehicle repair!
Take the torch and heat the head of what’s left of the bolts. Get them good and hot, and then let them cool back down for a half hour. What you’re trying to do is get the heat to move down the shank of the bolt into the threads, causing them to expand and then shrink. This sometimes will break the bond that prevents the bolt from turning out.
Once you get the bolts out, and if you need advice on how to swap out the U-joint, let us know.
Tester
Concentrate the heat right on the bolt head until it turns dull red…Let it cool a little and try to work it out. Sometimes tightening it a little first will help it to break loose…
Next time, use only six-point tools on these small fasteners to avoid rounding off the corners.
When you replace the bolts, use only Grade 8 on these critical fasteners. They will have six little radial lines on the head. They usually are fine thread…
Despite it’s reputation in popular culture, WD-40 isn’t a do-everything spray. All it’s actually designed to do is repels water (hence WD-- Water Displacement). It can be useful in keeping some stuff from rusting, but it’s not actually that great of a penetrant. I’m partial to the PB blaster brand, but all you need a good foaming penetrating spray. And then let it soak and re-respray it for days if necessary. This will make things much easier, assuming the bolt hasn’t become one with the U-joint.
WD-40 is flammable, Liquid Wrench is not. WD-40 is also sticky when it dries. You don’t want to use it as penetrating oil. Sears will sell you some sockets that remove rounded bolt heads. The sockets have to be hammered on. If the bolts break; cut the threads off and file them flush and drill them out with the right size drill and chase the threads out. It’s not that hard to get it done straight but it isn’t a “best way” either. It’s OK for exhaust studs because there isn’t any stress there. There is plenty on a u-joint yoke. When changing U-joints, you might have to melt the plastic that holds them in. Most times, you also have to hit them hard to get them out too. At least a 24 oz. ball peen hammer.
For Newbies!!!
If you can avoid it, DO NOT!!! get carried away and round off the head of a bolt. Once you’ve done that, it becomes doubly difficult!!
PB Blaster, 6 sided sockets, impact wrienches should all be tried BEFORE you put on a lot of torque.
If you are tempted to pull out the vise grips - SHOOT YOURSELF IN THE FOOT FIRST!!! Vise grips should not be used until you absolutely have no other choice - they should be used to grip it when all else fails, not before.
I second the grinder . . cut it off and buy & use new bolts. You wouldn’t want to use the old ones (ronded and beat up as they are) on the re-istallation anyway. A grinder with a cutting blade is a great tool . . just be careful, they cut with conscience . . . other parts may be damaged if you’re not careful. Rocketman
…and keep an eye on the spark shower direction and your gas tank…otherwise you to will become a rocketman…
:0)
Vice grips are even further down my list than that. A small pipe wrench would be a better tool as it actually grips harder as you apply torque. They do require a bit more headroom but preferred if it fits.