Vibration at my wits end!!! HELP ME!

[CJM]

Ok I have a 96 T100 SR5 x-cab, 3.4L V6 4x4, 197K on truck/trans and 50k on newer engine. If I cant figure this out im just gonna have to dump it off on someone..

It has a CONSTANT vibration, it vibrates the floor, seats and the steering wheel-infact the whole truck pretty much. It can be felt in any gear fwd or reverse, at any rpm range, take off, when on gas, strangely off gas its smoother but still there. Give it less gas and its not as noticable-still there tho. I just drove in fwd (4x4 with no rear driveshaft) and its still there

What I have done:
-REAR 2pc Driveshaft balanced, propeller shaft replaced, carrier bearing (2x), tailshaft replaced, u joints all seemed fine to them, I just pulled the shaft and they seem fine to me. They have NO play whatsoever.. done march 08

-All new brakes all the way around, calipers, rotors, discs, shoes, drums, wheel cylinders. No issues at all with brakes. done this past year.

-Tranny mount replaced, was worn. done over this past summer

-Motor mounts checked, all fine done this past summer

-Rear passenger side axle shaft, you replaced the bearing in there as well. T100s are known to have these go bad, I had it replaced this past summer and the vibration got much better. Before I had wheel hop severally-its gone now entirely. Could the drivers side be bad??? No way to tell without pulling it and bearing is 1x use, all parts are superseded by tundra parts so they all need to be replaced

-About the only thing I havent done is give it a tuneup, I got it with 50k on a new engine and I have only put on 15k so yea.

-The tires arent the greatest and cannot be balanced better than they are (trust me i been to 3 places). But even so off the gas truck is smooth. But, even so I traded YotaFun for his one day, still vibrates.


Whats left:
-Bad motor mounts. I checked these and so did a mechanic friend and my own mechanic-all said fine. Motor does not move around in engine bay when on gas powerbraking, all rubbers seem intact.

-One of the bodymounts on the cab isnt snug looking, I dunno but the rubber isnt against the mounts to well imho.

-Bearings, front, rear what have you..

-Trans has worn gears?

-Cant be the rear, thats disconnected right now and i changed the fluid 2x thinking that. 1st time no metal in there, 2nd time same. Fluid looked perfectly fine, no whine from the rear

I just dont know what to do anymore, YotaFun states it could be bad wheel bearings in the front and or rear. He drove my truck this past saturday and things after eliminating the rear driveshaft it could be the front ones as the steering wheel vibrates-but would the floors and seats vibrate too? He states that perhaps when I am on the gas they have more force on them and off less force means less vibration?

I just dunno anymore, this is becoming a headache as I cant drive the truck this way, its drives me crazy. What the heck else is there that could cause it to vibrate? I mean I replaced/checked nearly everything that is related to the drivetrain that one can service. about the only thing I can think of its the trans.. I did hear about problems surging with worn out plugs and wires not firing right and causing surges due to them not having a powerfull enough spark-but thats way out there imho.

So can anyone help me, throw some kinda ideas out? Im open to just about anything at this point.

[slosurfer]

Carrier bearing for your two piece driveshaft?

My other thought would be front or rear bearings

[CJM]

Carrier bearing for your two piece driveshaft?

My other thought would be front or rear bearings

Replaced the carrier bearing 2x just to be sure. It was previously bad as it had alot of play. Checked the front wheel bearing play-doesnt seem to be any and no hum or whine, but who knows. Rear, no idea..cant check unless its pulled..

Thank you..

[L33T35T Tacoma]

Has the front drive shaft been removed recently? It could have been installed out of time...

Have you tried putting the rear drive shaft back on and taking off the front drive shaft? This would eliminate that possibility if it still shakes with the front drive shaft out

[CJM]

Ill see about putting in into neutral on some stands and see where it goes. The last time we diagnosed the bad axleshaft by putting it on a lift and it still vibed.

Front driveshaft has NEVER been removed in the time I owned the truck. I am gonna remove it and check the u joints tommorow if I dont freeze to death outside.

[Cabin2N]

Is the frequency of the vibration change with engine rpm? dose it have aad?

[Robinhood4x4]

Having now worked for a vibration laboratory for a while now, I can say if you have the right kind of data, you can diagnose where the vibration is coming from based on the frequency.

You said it's a constant vibration, but I assume you mean that if it's not moving it's not vibrating. Therefore it's somewhere in the drivetrain but not including the engine.

Is it vibrating fast or slow? Fast meaning at about the same RPM as a driveshaft or Slow meaning about the same RPM as the tires? If it's fast then it could be originating anywhere along the path from your front diff to your rear diff. If it's slow, then it could be anywhere along the path from your left tire to your right tire.

[YotaFun]

I am going to add to this since i have test driven this truck myself and gave my own diagnosis.

The vibration starts right as the truck gains speed and your into the throttle, but it does not increase with engine RPM, the min you let the truck coast, the vibe is gone and teh truck rides smooth.

At first I thought possible u-joint issue, but I could feel the vibe strongly through the steering wheel then through the floor or seat of the truck, which leads me to believe that the front wheel bearing could possibly be going.

[CJM]

As with what Avy said, basically if your on the gas it can be felt-coast and its not there. It also changes and lessens when it shifts, you hit the gas it vibes-shifts into the next gear and the point it shifts it lessens, shifts back into next gear and bingo. Could the trans be going??

Now, I had a big issue with this where on take off with any gas or rolling it would vibe (not as bad just rolling). Turned out the pass axleshaft was bent, after it was replaced it was WAY better but still there. Again on take off it hops a bit but not nearly as bad anymore. I do wonder-did I screw up by leaving the messed up bent wheel/tire combo on that new axleshaft side? I only drove the truck maybe 500 miles this way period and I swapped the spare there.

Also, if you give it light gas the vibes there but isnt as badly felt, anytime you push the gas about 1/4 in it becomes really noticeable, higher RPM more vibe-speically once its up to like 3k or better.. It vibrates in any gear including reverse too.

What is truly noticable is the transfercase shifter flops around when you get on it, like I mean you can see it jiggle back and forth-its better since I replaced the one shaft but still jiggles. Also you let off the gas and get back on you can feel the drivetrain slack and the vibe worsens to a degree.

I dunno, i pulled the d/s last night and thanks to the last person the nuts are all stripped so I need to go to toyota and get new ones, which will take a few days so I wont be playing much for now.

What baffles me is when a wheel bearing goes, you get a very annoying hum-none of that.

Basically it boils down like this:
The only thing I can recall that could have caused this was going to paragon ORVP (doubt it), or I went to some local trails and there was hardpacked sand and some whoops. It was night and none of us that went saw them and we all bounced like crazy till we managed to crawl along. When I say bounce the entire truck was bouncing around like you bounce on a quad on whoops. It could be that time and thats what I think...

What I plan to do is replace the front bearings first, see if they matter-they probably havent ever been done anyways. If nothing changes then its the other axleshaft, what else can I do realy. I cant sell the thing like this, aint no one gonna buy it for more than 1500 bucks, and im getting sick of playing with it..

[CJM]

Also with the rear driveshaft disconnected it vibrates just the same. I can clearly see the x-case shifter jiggle around and feel the vibration in the floor right over the drivers side very well. No rear driveshaft so no rear axleshafts to mess with it? Its like i never removed the rear driveshaft at all.

If the truck is in 2wd, and the hubs are unlocked does the front shaft still spin?