Help! (another driveline vibration thread)

[scottm]

Hi guys, haven't been here in a while. My remaining 80 has been reliable and needed little but oil and gas. But I recently made the mistake of pulling the running boards and trailer hitch to sandblast and bedliner them, and apparently upset the delicate feng shui of my truck. Details:

-'97 base-model FZJ80, 159k, no lockers or mods, original most everything.
-Fairly new Michelin SUV tires all at good pressure.
-No recent mods, heavy maintenance, or hard use.
-Birf job done a few years ago by me, birfs looked worn, swapped them left-right. They're mostly quiet, sometimes I can hear them slightly.
-Vibration under accelleration from 30 to 50 or so, getting heavier and beginning at lower speeds.
-Found one front wheel bearing loose, adjusted it.
-Lubed the driveshafts, they haven't been done in many years.
-Fluids are all full, front diff fluid is green as usual.
-No noticeable slop in the input or output bearings, but I haven't dropped the driveshafts yet. I'll mark them and drop them when I get this info.
-Long trip coming up the 2nd, we need the cruiser, even if 2wd.

Question: What fuse do I pull to keep the center diff locked when I switch from lo to hi range? I have a CDL switch salvaged from the wreckage of the 40th, but don't really want to tear up the new wood trim to put it in. I've done this before.

There's lots of info on this subject when I search, and I'm following the many great suggestions, but I haven't seen what fuse to pull, and it isn't obvious when I look at my fuse panels. I called IdahoBro, but he's on the road in Texas and his cell isn't getting good reception. There's been much talk of replacing the 80 in my household, this isn't helping. Advice appreciated, thanks.

 

[scottm]

Found it, "DIFF", ok that was pretty stupid. I'll go drop my driveshafts now, one at a time of course.

 

[Montana Cruiser]

...... have you reinstalled the hitch and running boards and the "vibe" is still there?

 

[scottm]

I threw the parts in the back, hoping that would be close enough to help, but the vibe is getting worse.

Any trick to separate the front drive shaft from the drive plate on the transfer case? I've got the nuts off, tried prying and hammering, it won't budge. This is going slowly...

 

[scottm]

Has my truck ever felt this smooth before??? The front driveshaft is out, and I think I've narrowed it down. The rear U-joint is a bit notchy, the front has one axis frozen and the other has a cracked bearing. Perhaps I should've lubed it more often. I'm tempted to take out the rear driveshaft and check it's health, but not right away. I'm happily 2WD with no ABS, and no vibration, and I can drive it this way on our family vacation. I guess I need to locate a good driveline shop, this isn't a big 4WD area, but I have time.

 

[scottm]

Question: I paint marked the drive plates and yokes to put them together the same, but do I care about that if I get the driveshaft rebuilt and balanced? I don't trust the paint marker to hold up, I should mark with a chisel or punch if this will be important.

I'd like to use good bearings, probably CDan for a bunch of kits the rebuilder can use?

 

[-Spike-]

The only alignment that should matter is the slip yoke on the driveshaft, and not even that if you're having it balanced. Just make sure it goes back together with the u-joints oriented the way they came out- I never can remember if they're in-phase or out, but I do know the front is oposite from the rear drive shaft.

If you're having it done somewhere and you ever intend to wheel it, might be a good time to have it re-tubed with thicker tube. Not critical by any means, especially if you intend to go with a higher than 3" lift as you'll probably change out the driveshaft in that case. Just something to consider.

-Spike

 

[scottm]

Nope, it'll never be wheeled, I'd find one with lockers if so. I'm very familiar with the phase-cancelling of U-joints, wrote my senior paper on it, so I understand why they did it this way on the 80.

 

[Tools R Us]

Probably doesn't make much difference but, I have always marked marked everything and reassembled the same way it came apart. I use a center punch to make the match marks.

 

[KliersLC]

You can change out those joints with napa joints in about an hour, reinstall, and have a fully functional rig for your vacation. OEM joints are the best, but I have had great success with napa joints in several other rigs. If you don't have the tools available, maybe throw the shaft in the back and stop by a mudder's place along the way. All you really need is a hammer, screwdriver, pliers and a couple of sockets you don't ever want to use again....

Good luck,
Dan

 

[scottm]

NAPA? My search here found indications that this is a super-critical measuring and balancing thing, only to be done by a specialty shop. Of course, that was my brother's post, when have I ever listened to him . I have a machine shop handy, where I can make tools and use the 20-ton press. I've never messed with a spider, not sure how to go about it, maybe there's info in the shop manual?

 

[landtank]

NAPA? My search here found indications that this is a super-critical measuring and balancing thing, only to be done by a specialty shop.

You have to be kidding, I've been swapping u-joints since the mid 70s. Pull the clips, hammer them apart and use a big C-clamp to press the new cups in. Both ends in about an hour.

Just watch the slip yoke alignment and which way the zerks face.

 

[Tools R Us]

... I have a machine shop handy, where I can make tools and use the 20-ton press...

A press and a set of sockets for spacers, will make short work of it. It's an easy job.

 

[KliersLC]

Well,
The FSM probly has the procedure, but here is the skinny:
First step is to spray down with penetrating oil,

Then remove the clips on the inside of the yokes(see your previous pic with the chipped cap, the end of the clip is just to the left and down from the chip) Remove these with a screwdriver or punch, a hammer and needle nose pliers. OR any combination of the threee.

Then use a big punch or a socket to drive downward on one axis until the center piece hits the yoke. Then use pliers to work the cap free if it doesn't fall off.

Side note: A big vise or press works fine if you use a socket that has a larger inside diameter than the OD of the u joint cap. A vise is handy anyway to hold the shaft while you are pounding.

Then invert the yoke and repeat with the other side. You now have removed the caps from the Y axis and can separate the yokes. Repeat with the yoke that has the caps and joint still attached. Pay no mind to the needle bearings flying everywhere.

You now have two joint free yokes. Install with a vise, being sure not to get caught on the needle bearings. I like to do this by seating one cap in place with the joint loosely in the yoke but pushed into the cap as far as possible. Then put the assembly in a vise and press till the cap is flush. Repeat X4

Once you have the one end back together, repeat on the other side and reinstall the shaft.

I hope this helps and anybody else, please feel free to add or correct anything that I left out.

Dan

 

[KliersLC]

Oh, and Napa joints are VERY good

And I type slow...

 

[landtank]

I personally hate the vise idea, too hard to manage the shaft. Get down on the floor with a good c-clamp, especially if you're by yourself.

 

[scottm]

It's starting to sound like this is something at my skill level. I hosed it down with PB Blaster, put it in a garbage bag, and it's in the back of the truck. I've got a full set of tools at the shop, and plenty of big tools if I need them. I could probably do it at home, but the guys at the shop are usually amused to see an engineer wrenching on stuff like this. Pity, engineers should do more of this, maybe they'd know how to design cars like they once did.

NAPA has standard joints, performance joints, and super-strength joints. The performance are the cheapest, super-strength isn't much more, I'll see how fast they can get them here.

 

[landtank]

be sure to smack your thumb with the hammer, always a crowd favorite!

 

[Tools R Us]

be sure to smack your thumb with the hammer, always a crowd favorite!

Be sure to bleed a little, that always gets them going!

 

[-Spike-]

Blunt-trauma bleeding is impressive!

-Spike