yotafreakshow

Hey Toy lovers, I have a stock 89 4x4 pickup, 5 speed, 22re, just turned 200,000 miles. I have owned the truck for about 65,000 of those miles(3.5 years), and have had a slight vibration that's getting worse. It occurs most intensely between about 40-50 mph- while accerating or decelerating, but is starting to show up at almost any speed. If I match the engine and drivetrain speeds so there is no tension on the driveline or push in the clutch, it goes away. There is a kind of whine that rythmically mimics the vibration. I have gotten new tires/balanced, suspension alignment ect. Barring the possibility of a bent axle/driveshaft (because of it getting worse over time, and the fact that I deal out a mild amount of punishment), could my differential bearings be worn, sending the 3rd member out of balance, or could the gears be so worn that they kind of "bounce" because of excessive play? It feels like a springy sort of low freqency vibration, coffee gets splattered out of the cup, mirrors are tough to see out of, ect. Really annoying always.
The 30mm nut of the tcase flange is tight, ujoints are new and in phase, pinion and tcase output bearings have no play or seal leaks. Rear axle bearings have no play. Rear engine mount has a slight crack in rubber, not even close to seperating though.
Anyone got any ideas?
Thanks

yotafreakshow

It also makes my cheeks jiggle, and I'm skinny.

Anyone?

flecker

unlock your front hubs! Winters over

Seriously though, you have tried everything I would have... The bearings can and will fail but they ussually make a sound like a jet taking off
It's very possible to have an out of balance driveshaft, or maybe bad rear shocks? Worn or broken spring pack? Does the third have gear oil in it?
How about the tranny mounts? Are they busted or rotted? Whats the clutch like? And the flywheel? Just a few things off the top of my head... the front shaft will spin a bit too even on 2 hi, is that worn or bad ujoints?

934rnr

Put it up on jack stands spin the rear tire that will tell you if you have a bent shaft. Also it may be a loose pinion nut on the 3rd. Mine was quite loose even though everything felt tight. I am glad I did a lockright install that day. I torqued it down with the wheels on the ground and someone on the brake it is torqued to something like 130-145 ft lbs. Remember to steak the nut when you are done. The other thing that comes to mind have you checked your t-case fluid? If it is extremely low it can cause a vibration for some reason I have no clue why but mines done it.
Another idea is check the rear suspension U-bolts if those have loosened up or your axle shifted on the leaf springs at all it will cause some vibrations.

mtnfreak

I've got a nearly identical problem. I know it's not the u-joints - they were just replaced and the vibration is still there. Any help is appreciated.

yotafreakshow

[QUOTE=flecker]unlock your front hubs! Winters over

I can drive 75 w/hubs locked and not even feel it! (I've only forgotten to unlock a couple of times, winter's never over in the mountains.) I think the front end is in awesome shape. There is definately a whine coming out of the rear end though, kind of like a low pitched squeal, it's always been there and hasn't gotten worse. My 85 4runner has the whine as well, only 90,000 miles on it. I am wondering if I can pop off the diff cover to access the third. Maybe pry gently between the third member and diff housing to see if there is any play in those bearings.
About the only thing I haven't gotten into on this truck are the diffs, so I'm curious if that method would work to diagnose a worn bearing issue.

934rnr

[QUOTE=yotafreakshow]You won't know till you pull the diff out you are not gonna be able to pry the diff open to look at it save yourself the headache and jack the rear up drain the differental disconnect the 4 bolts holding the axle shaft per side on disconnect the brake line holders and pull your axles out enough so you can get your diff out.

With the diff out check the center section for side to side play there should be none.. If there is loosen the locks and turn the adjusters until there is none tighten to spec take over to a shop have them check the backlash on it.

yotafreakshow

I have a few things to check first, pinion nut, bent axle, driveshaft, but my gut tells me the third has to come out. Sounds relatively simple, barring any frozen bolts, ect. Thanks for the input.