Vibration in driveline (somewhere)- '80 Hilux

[tomcolins]

So... Drove to Flagstaff to pick up some split rims (excuse for a much needed trip) (or the other way around?). Came down out of the mts north of the Gila Wilderness (NM) and noticed a slight shimmy at hwy speed, say, 70?

Figured I dropped a wheel weight or something. Kept eyes peeled for a shop. Didn't fret much. Got to Flagstaff two days later, shimmy was worse. Now happening at like 60 mph. Also less like a shimmy and more of a vibration under load. Got all five wheels balanced, swapped in the spare as tire shop guy suspected a bulge in one tire ( I saw no bulge, but whatever. Worth a shot)

Vibration continued to worsen. Traveling a lot on secondary and county roads, NF Roads as well. Speed not much of an issue but now beginning to be a problem.

I had a flex disc go out on an old station wagon once and it felt very much like this did. Wobbly sort of vibration with gas applied. Deceleration smoothes out the wobble. Riding in neutral with engine at idle, not much if any vibration.

Got to where 40 mph was painful. I pulled out the rear driveshaft when I couldn't stand it anymore, about 300 miles from home and drove home with the front axle. Should have done that 300 miles sooner. Could now drive 65. But still could feel a shimmy.

Driveshaft is suspect. Didn't see any dents. U Joints look old, but don't "clunk" and aren't loose when twisted by hand. The rear is def a problem. The current vibrations are probably taking me off the right track... I guess a lot of things could be happening at once. I'm starting to get unfocused.


Thoughts?


DB

 

[inkpot]

Howdy! Did you try greasing the ujoints and slipjoints? If not, then start there. Not better, then replace ujoints. Not better, take to driveshaft shop. Could be a slight bend or worn out slipjoint, neither of which you will find without a shop. John

 

[tomcolins]

Thanks John-

I didn't grease it at the time, though I'd rebuilt the front axle a month or so ago and had changed the oil in the diffs, checked the tranny and transfer case and lubed everything then...

It's out now, so I'll probably replace the U-joints for good measure... Though I still get a bad feeling about the whole thing.

Can an ungreased fitting really cause that much of a wobble in the driveline?

 

[liljlandon]

heres how i think of it,

the grease lubricates and 'cushions' the metal on metal contact, remove the cushion and lubrication and you have a coarse surface being pushed against a coarse surface. It doesnt only add to the wear created by friction, but now is out of its original alignment. Which is pretty crucial when you are spinning at 3000 rpm!

But, someone may know better than me. just my opinion!

 

[EVILSPOTTER]

Does the spline of your rear shaft have any slack in it?

 

[tomcolins]

Slack in which direction? Rotational? I can't twist it any, but it moves freely in and out of the shaft

 

[EVILSPOTTER]

How about radial movement? Secure the flanges & attempt to move the spline in a direction perpendicular to the axis of the shaft. It does not take much of this type of movement to cause substantial vibration. I noticed that you live in God's country, do you have a driveshaft shop that can replace your splines?

 

[Dedtruk]

If the vibration dropped when you pulled rear driveshaft, did you check tightness of rear pinion nut? Tightness of transfer case output nut/bearings? Condition of rear pinion bearings? Gear lube in rear diff (since you just lubed, maybe developed a leak or underfilled)? Sure, check the u-joints (bet they fail at a faster rate than the slip joint splines, but check splines too) but it seems logical that when you took the torque load off the rear driveline and the vibration dropped, that it's somewhere in that area ... I've been chasing a similar vibration, so just adding my $0.02 ... HTH ... Geez, your rig is 1980? First Toy 4WD I owned was 1980, great rig ... but have you ever checked rear wheel bearings? 31 years is a long time! : )

 

[tomcolins]

dedtruck/evilspotter

Thanks for the input... I have been absolutely slammed with work the last few weeks and off of here. I haven't snooped around too much in the pilot bearing/pinion etc... I do live in god's country, AKA BFE. I sent the shaft off to a shop via USPS and expect it back with updates and a refresh if needed. We can't even get inspection stickers in this town, much less machine work.... I'm kinda hoping, even if irresponsibly so, that the shop will sort it out. Really don't want to have to dig around in the rear end. I don't think it's the rear bearings, but worth a look. Just need a day to get it up on the stands and look her over. I'll keep you posted...

Thanks again-

DB

 

[tomcolins]

If the vibration dropped when you pulled rear driveshaft, did you check tightness of rear pinion nut? Tightness of transfer case output nut/bearings? Condition of rear pinion bearings? Gear lube in rear diff (since you just lubed, maybe developed a leak or underfilled)?

I would think if the pinion bearings went that the seal would burn up pretty quick, leaking oil out and making itself known. Can the bearing get wonky and still leave the seal intact?

There is plenty of oil in the rear...

 

[EVILSPOTTER]

Grab the companion flange of your pinion shaft & check for movement. A thirty year old differential ought to have a little slack in it, but if you watch the gap between the casting & dust seal as you try to move the pinion radially anything more than a few thousandths should be cause for concern. Give the companion flange of your tailshaft the same quick check. The way that you describe your vibration ramping up on your trip could be a bearing failure, but if it is it will be pretty obvious. Natural wear happens so slowly that we don't notice it so much, but it sounds like this trip put some metal shavings in some gear lube somewhere. If you are looking at suspects other than the driveshaft you might want to drain some gear lube & look for glitter.

 

[tomcolins]

Grab the companion flange of your pinion shaft & check for movement. A thirty year old differential ought to have a little slack in it, but if you watch the gap between the casting & dust seal as you try to move the pinion radially anything more than a few thousandths should be cause for concern. Give the companion flange of your tailshaft the same quick check. The way that you describe your vibration ramping up on your trip could be a bearing failure, but if it is it will be pretty obvious. Natural wear happens so slowly that we don't notice it so much, but it sounds like this trip put some metal shavings in some gear lube somewhere. If you are looking at suspects other than the driveshaft you might want to drain some gear lube & look for glitter.

Well it's taken a few days for me to get back to the truck, but I checked for play at the companion flanges (transfer and rear pumpkin) there is some rotational slack in the transfer end, say 3/16ths of rotation before it takes up? the Differential end is tighter but there is a bit of slop inside the diff itself. This would be backlash, yes? Not sure how much is accaptable... I guess I could look it up but I don't think that's where the vibration would be coming from.

I didn't feel any movement when pushing the flanges side to side, nor pulling/pushing in and out. The nuts themselves are loose save for the key holding them in place. Is it a good or bad idea to try to put another turn on them?

I sent my driveshaft off to a shop last week and it should arrive tomorrow with new u-joints. Everything else checked out. So I'll put that on and see what happens... Maybe I'll drain the oil to inspect as well....

 

[tomcolins]

U Joints

So, after all of that the u joints were to blame. Kinda not worth all the hubub. I have never had them go bad without feeling it klunk before vibrating like that. but the shaft was balanced a bit and lubed up and now all is well. Front gets attention next. I'll still get into the gear oil to inspect but I'm way happy about her handling as of today. Especially now that she is riding on some Australian split rims (not cause of vibration, though you should see the weights on those things)! Kind of a rubber overdrive... cruises right on down the road!


Thanks for all y'all's help!

DB