So I bought a pretty beat up 91 4runner and I've deemed it my project. I'm fairly new to mechanic work, but figuring it out is part of the process. These threads have been great.

So my Drive shaft was hanging on by one bolt when I pulled it into the garage. It didn't have any damage to it and luckily I didn't have to pole vault the thing off the road to find out. We put new nuts and bolts in with some loctite but I noticed they had locking bolts originally and those obviously weren't enough to keep them on there. Any suggestions for making sure they stay in place? I'll be sure to check them regularly, that could have been really bad.

 

.""......Locking bolts........and those obviously weren't enough to keep them on there.""

Whoa buddy. You are jumping to a big conclusion.

You don't have any idea what your 'pretty beat up' truck has endured, and how tightly the last 'mechanic' tightened them.

The original bolts and lock washers are more than sufficient.

 

The drive shafts are held on with just that, bolts nuts and lock washers. The torque spec is 54 ft lbs, if you torque them correctly you won't have any issues

 

True. It will probably be something I'll just check regularly then. That's the down side to an old truck like this one, I have no idea how badly they beat it up. Guess I'll find out one piece at a time.

 

When you grease the u-joints, and double Cardan joints, it's easy to check all the torques on the nuts all up and down the drive line.
You should grease all the u-joints etc, every 15,000 Miles, or 18 months, whichever comes first.
Unless it gets rough usage, IE: operating on dusty, muddy, or salt-spread roads. Then you should re-grease them every 10,000 miles, or 12 months.

That's according to the FSM, and it matters for the lifespan of the u-joints, etc. In fact, it makes a BIG difference
I do mine at least once a year, and then again if they get submerged. A deep puddle, stream, etc. Check the FSM for all the grease points. They do not come with the grease-zerts every one uses these days. The just have a small bolt in the holes. I replaced the bolts with zerts. ALL of them. It makes life SO much easier to just plug the grease gun in, and pump it a couple times. Once the grease comes out of the needle bearings, and so on, that's enough.

Good luck!
Pat☺

 

I’m fairly new to cars as well but ChrisFix on YouTube is a massive help. One thing he does is mark a line straight across the bolt heads and onto the driveshaft flange with a paint marker. If the bolts loosen up on you the lines won’t line up and you’ll be able to tell that you need to re-torque them.

 

I've been looking a bit and can't quite tell, what size zerks should be used? I know there's 1/4"-28 and there's M6x1.0. I'm pretty sure we need the metrics but I can't find a difinitive answer

 

Welcome
Let me know how the restore goes, I have a lot of parts for it. My parts truck is a 94 but I'm sure the parts will interchange. You should post some pics
Hump

 

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Actually I have a parts truck too. Just pulled the engine out of it, the rest is mostly intact. It's a 91 4runner v6 4x4. It's kind of a junker but there's a few good parts. Let me know too if there's something youre looking for

 

I am pretty sure I used the metric ones. If you can buy one, compare the threads with one of the little bolts. I have a couple of pretty extensive tap and die sets, and that's what I used to check the threads. Found the die that fit the little bolt, and bought whatever number it was.
Worst case, buy a set of each, the standard and metric ones. They're not all that expensive, and see what fits into the holes

Some of the holes are pretty hard to get to, so make sure you've got the right zerts before you go to put them in. There are a few out in the open and easy to get to, so you can finger tighten at first to be sure they go in properly. A real shallow, 1/4 drive socket on an 4 or 6 inch extension will, at least, start the ones that are hard to get to.
You can put some wadded up paper, or small piece of rubber into the socket to make it shallow enough to install the zerts. I made mine shallow enough that the "bolt head" part of the zert was just down in the socket a little bit, and the threads were sticking out almost all the way.
This picture, from the FSM, shows them already installed, but when I bought my 4Runner, there were just bolts in the holes. Note that they show 90° zerts in the spiders. I used 45° ones and they are much easier to get to. Just my experience though. By the way, I am still on the first set of u-joints, and Double Cardans. 177,000 miles so far and still in good shape!

One of the easy to get to, out in the open, ones.

But I am pretty sure it was the metrics I used. This was over 25 years ago, though, and I've slept since then. Once or twice, anyway
Pat☺