Help! (another driveline vibration thread)

[concretejungle]

Are you sure your reading your brother's posts? .................You're way over thinking this job.

That's exactly the problem. He is Doug's brother so that has some merit.

 

[scottm]

That's exactly the problem. He is Doug's brother so that has some merit.

Overthinking Doug's thinking? Not enough brain cells! I didn't do this nearly as thoughtfully as he would've. Usually I end up re-accomplishing a few things, but so far so good. I wish I'd gotten the joints from cDan, but I thought I'd be getting this back together that weekend. I ended up having to swap the grease fittings, not too painful. Now that it's together, I'm going to take a good look at the rear ds bearings.

 

[Jacques Villeneuve]

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.

Is it necessary to lock the the diff to remove or work on the U-Joints? I have the same vibration symptoms described above that started after hitting a large speed bump at Home Depot (sort of mall cruising).

Thanks in advance.

 

[scottm]

Is it necessary to lock the the diff to remove or work on the U-Joints? I have the same vibration symptoms described above that started after hitting a large speed bump at Home Depot (sort of mall cruising).

Thanks in advance.

No, but it's necessary to lock it to drive around with one driveshaft removed. The all-wheel-drive mode will send torque to the driveshaft giving least resistance, in this case the driveshaft that isn't there. There's a sort of clutch pack that makes it kind of a limited-slip center differential, and it will wear out if you don't lock the diff. That'd be expensive and a PITA.

 

[96r50]

Add to that the fact that your truck can/will roll if it is parked on even a slight slope with one driveshaft out and the centre diff unlocked. Make sure you set the parking brake and chock a few wheels. Or if you have a flat driveway and four big jackstands, put the truck up on the stands. Then you can put the centre diff in neutral which will make it a lot easier to get at all 8 bolts/nuts on the driveshaft.

 

[Bear80]

Also NAPA has droped the better GMB joints for some lesser MOOG joints. I don't like MOOG personaly and NAPA also went up on the price.

 

[Jacques Villeneuve]

Vibrations occur under acceleration and start at 30mph and taper off at 55mph then resume at 65mph.

Update:

Replaced all U-joints. Both driveshafts were balanced. Using the CDL, I drove with the just rear driveshaft, just the front driveshaft and both in .

No vibrations with just the rear driveshaft.
Mild vibrations with just the front driveshaft.
Largest vibrations with both driveshafts in (same pattern as with just the front driveshaft in) (slightly less when CDL engaged).

Rotated and balanced the tires. Checked all four brakes (no issues).
I do not think it is a wheel bearing (turning left or right has no effect on the vibration).

Ideas?

I will be taking into a shop in two days that uses electronic ears to listen with.

 

[Jacques Villeneuve]

After reading many threads on vibrations related to lifts and driveshaft angles, a thought came to mind. Since my problem started after I hit a speed bump at 10mph, perhaps some mounting bolt broke and the angle the driveshafts make with the pinion and t-case change under acceleration (i.e. under load) causing the vibration same as when a truck is lifted.
Another thing I noticed (and I don't think this was happening before the speed bump hit) is that sometimes with the gas on, the automatic gear shift lever seems to move forward and/or backward in its enclosure, like the undersides are moving around. Is this normal?

Thanks in advance.

 

[Atticus]

Vibrations occur under acceleration and start at 30mph and taper off at 55mph then resume at 65mph.

Update:

Replaced all U-joints. Both driveshafts were balanced. Using the CDL, I drove with the just rear driveshaft, just the front driveshaft and both in .

No vibrations with just the rear driveshaft.
Mild vibrations with just the front driveshaft.
Largest vibrations with both driveshafts in (same pattern as with just the front driveshaft in) (slightly less when CDL engaged).

Rotated and balanced the tires. Checked all four brakes (no issues).
I do not think it is a wheel bearing (turning left or right has no effect on the vibration).

Ideas?

I will be taking into a shop in two days that uses electronic ears to listen with.

Is the phasing correct on your front drive shaft?

 

[Jacques Villeneuve]

Is the phasing correct on your front drive shaft?

Yes it is. Originally, the previous owner must have had the front shaft out because it was in phase. I had the shop that balanced it place it 90 degrees out of phase before balancing. Of course they gave the usual "nothing on this planet has a driveshaft out of phase".

I'm going to crawl under it again to see if I can poke around for any loose mounts, parts,etc.

 

[scottm]

Is the rear driveshaft IN-phase?

Had you lubed your driveshaft recently before the speedbump incident?

The PO had the front driveshaft out, that's odd. Maybe there was a related problem then, seems like it would have had to have been vibration for most POs to do anything like that. Maybe it had new U-joint bearings? IdahoDoug had a detailed posting about official Toyota procedure for carefully shimming each bearing. Not doing so could leave the U-joints slightly off-center, maybe.

 

[Jacques Villeneuve]

Is the rear driveshaft IN-phase?

Had you lubed your driveshaft recently before the speedbump incident?

The PO had the front driveshaft out, that's odd. Maybe there was a related problem then, seems like it would have had to have been vibration for most POs to do anything like that. Maybe it had new U-joint bearings? IdahoDoug had a detailed posting about official Toyota procedure for carefully shimming each bearing. Not doing so could leave the U-joints slightly off-center, maybe.

Yes the rear driveshaft was and is in phase. I lubed the u-joints several months ago. The old u-joints that I removed last week were a bit sticky but they were lubed.

I've had the rig for three years now with no driveline issues until this. The PO may have had the u-joints replaced and that is why the front driveshaft was in phase incorrectly.

I'll look for IdahoDoug's post on shimming the beraings (but as you know, there is a mountain of info here to sift through).
Thanks.

 

[scottm]

Oops, purely terminology here, but technically the rear driveshaft is 90-degrees out-of-phase, like most rear-drive vehicles. The front is also out-of-phase once installed at normal suspension height, because of the angles, but it would be in-phase in a standard rear drive setup.

My question about lubing was concern that you over-lubed the slip-joint, maybe damaged the t-case when you went over a bump. It's happened before. Did you lube before the parking lot bump? IdahoDoug is again the guru of this stuff.

 

[Atticus]

Oops, purely terminology here, but technically the rear driveshaft is 90-degrees out-of-phase, like most rear-drive vehicles. The front is also out-of-phase once installed at normal suspension height, because of the angles, but it would be in-phase in a standard rear drive setup.

Come again?

 

[scottm]

When a U-joint is rotating at an angle, the output rotation accelerates and decelerates twice per revolution. It gets more pronounced at more angle. A second U-joint at that same angle can cancel the accel/decel effect if it's 90-degrees out of phase. It's output will decelerate when the driveshaft is accelerated by the first U-joint, and vice-versa, for a smooth output. That's a double cardan joint.

If you have a U-joint in your socket set you can spin shafts and see the accel/decel in action.

 

[Jacques Villeneuve]

Oops, purely terminology here, but technically the rear driveshaft is 90-degrees out-of-phase, like most rear-drive vehicles. The front is also out-of-phase once installed at normal suspension height, because of the angles, but it would be in-phase in a standard rear drive setup.

My question about lubing was concern that you over-lubed the slip-joint, maybe damaged the t-case when you went over a bump. It's happened before. Did you lube before the parking lot bump? IdahoDoug is again the guru of this stuff.

The slip joint is fine and not over lubed but I do understand the concern. The dirveshafts are as per the Factory Service Manual so that is not the issue at this point. There is no lift in the vehicle's suspension at all.

 

[scottm]

If the driveshafts are perfect there's still some vibration in them, held by the bearings at each end. Any slop there? I still wonder about the PO having the drive shaft out. Do you know the mileage when that happened? I've heard of 80s running over 100k without a lube job and no problems.

 

[Jacques Villeneuve]

If the driveshafts are perfect there's still some vibration in them, held by the bearings at each end. Any slop there? I still wonder about the PO having the drive shaft out. Do you know the mileage when that happened? I've heard of 80s running over 100k without a lube job and no problems.

I bought it with 94k miles on it and it now has 155k on it so the driveshaft was out before the 94k mark.

 

[scottm]

The overlubing situation:

Rick,

Overgreasing the slip yokes will not cause vibration. But if you persist, one day you will be unlucky and hit a bump leaving the spot where you greased it and crack the wall of the center diffy. You're basically turning the shaft into a hydraulic ram, and when 2000lbs of 80 rear end comes down on it expecting it to shorten (plus the leverage ratio of the angled shaft), there's going to be a force spike measured in several tons. Take my advice, cease doing this. I pump enough times by hand so that the shaft *begins* to move. Then I let the truck sit for a while to let the grease squeeze down the shaft before moving it. I also get the smell of grease on the exhaust letting me know the grease quantity is sufficient to lube the splines all the way to the ends.

IdahoDoug

Still looking for his U-joint centering info...

 

[Jacques Villeneuve]

I have done a lot more searching and reading. Most indicators are that it is a damaged front spindle bushing (front because there is no noise/vibration when I remove the front driveshaft).
However, the tech who has my truck now has not finished using his electronic ears to pinpoint any unusual driveline noises so I am not sure.
Also, from what I have read, when a front spindle bushing goes there is a rumbling noise like driving over a washboard BUT not a vibration like I'm experiencing (between 30 and 55mph) or am I wrong?
Thanks in advance.