The rear diff makes no noise... The other axle was checked for runout and nada. We didnt pull it, but the dial indicator said it was fine (as per the FSM test).

The truck is an automatic, does it has a flex plate? Where would it be if it does?

Where is the harmonic balancer?

The truck still turns the front driveshaft even with manual hubs b/c AFAIK it still has add components in there, just warn manual hubs on the end. Locked or unlocked hubs it

Im waiting to get the bolts/nuts for the rear shaft right now as the originals were hell to remove. Then Im going to pull the front shaft and see how it goes.

Like I said, as soon as you take off the vibe begins and you can watch the x-case shifter wiggle-with the rear shaft on or off. More gas you give the worse the vibe gets-if your easy on the gas you can barely feel it. When it shifts the vibe lessens then the slack gets taken back up in the drivetrain and it goes vibrating again. more rpm, more vibe.

What really left if you think about it?
-Bearings front and 1 rear (the axle shaft I didnt replace)
-Front shaft, the vibe begins in the front and its right under my seat-where the front driveshaft is kinda.
-Or engine/trans? Harmonic balancer someone suggested, what is that, where is it? what does it do?

Im going to remove the front shaft and see what happens, will report back then.

Flex plate is what connects the engine to the transmission.

Harmonic balancer is on the front of the engine driveshaft. You can see it if you look on the front of the engine.

As I mentioned in an earlier thread- it should be pretty easy to tell which end of the drivetrain the vibe is coming from because everything prior to the differential turns at least 4 times faster than after it, so the frequency is higher.
Same with fore/aft of the transmission, depending on what gear you are in.

You can eliminate a whole lot of things right off the bat that way, but its all pretty tough to do over the internet...

Yea, sounds kinda hard to play around with tbh...

I Just checked the front driveshaft while it was on the truck, its greased up well, has no play and seems to be fine.

My front diff seems to have a small leak where it seals, on the lower part near the pass side, its deff gear oil. How does one even get to it to check the levels, I looked and see no check plug like the rear only a drain plug.

Also, noticeable jump into gear if I go from P to R or P to D. If I go from N to either gear it doesnt do that. Could be related to the fact that the shifter mechanism wears out on these since its a column shift and thus you need to slam it home into park to make sure it latches.

Put the truck into N and just hit the gas..seems to melike the engine has an awful lot of roughness to it and possibly the cause? Its not smooth feeling tbh..i dunno

As for the front shaft and being engaged or not, truck in any gear and I could turn the shaft by hand with hubs on or off (in 2wd only). It doesnt appear to have any missing weights either or be bent.

Checked the motor mounts as best as possible, while they look old they dont seem to have movement at all-I pried the hell out of them and nothing.

I went and ordered the new driveshaft bolts/nuts/washers, freaking things are 1-3 bucks each..68 dollars and by next week i will have them.

This whole situation tbh by now is beyond my level in mechanics, I have an idea if what you guys speak of but cant really check them to well. I tried a few shops, at this point maybe ill give the stealer (they will probably rape me for a grand) a try and forgo the thought of the cost and just be happy if they can fix it. I mean, its getting to the point where my personal mechanic hasnt a clue and is sick of seeing me. They can at least diagnose it for maybe 100-200 bucks, then maybe I can at least start on the right track.. What do you think?

btw, i appreciate all the help still. It bothers me that 3 independent shops cannot solve this though.

I really feel the issue has to be somewhere in the engine, everything else has been eliminated besides the flex plate and harmonic balancer-the drivetrain itself (shafts and all) seems to be fine.

How could I check the harmonic balancer, this truck had a new shortblock installed by toyota about 2 years before I got it. How would I check the flexplate?

I think the flexplate would have to be checked after you pull the engine. Not sure if there is a way to inspect it otherwise.

This (I believe) is the harmonic balancer on the the 3.0L. It's gonna be the same position as the 3.4L. On my 1985 Celica, the timing ring was rotating freely on it's own... <img src="/forums/images/graemlins/frown.gif" alt="" /> The harmonic balancer is metal and rubber. If the ring has separated from the rubber, you should be able to either see it or feel it. <img src="/forums/images/graemlins/wink.gif" alt="" />

Thanks Bam, im gonna see about someone looking over it again. Like I said as a last resort its the stealer or bust, if they could at least figure it out I can repair it somehow.

Thanks again to everyone btw..I soo hope i can fix it and I dont have to sell the truck for parts or something..

Put the rear driveshaft back on since I got some new bolts-seems a bit smoother b/c of this-I know the old bolts although tight werent in the best shape. Could just be me..

I put the truck on some stands and put it into gear and just revved it up a bit.In gear, with the rear just going it shakes a bit, if i lock the front in 4wd it shakes incredibly bad.

In N and in the air it has a roughness in the engine imho...

Took off the rear drums, checked both rear shafts, both seem absolutely fine.. Put truck into gear and watched-if they have run out (I dont have a dial indicator) then its news to me, they looked
straight and true.

Then I took it down the road, it may just be the fact it was warmed up but it didnt vibrate as much as I thought it was doing.

At this point im at a crossroads, axle shaft seems fine, driveshafts F/R seem fine, maybe it is the tires, but why it rolls smoothly when not in gear or on the skinny pedal is beyond me.

I really think the vibration is in the front somewhere, its really felt in the cab of the truck ever since i replaced the axle shaft.. I think im gonna take it to the stealer and see if they will at least diagnose it and if they can we'll take it from there. Like I said a whole bunch of friends who are mechs and my own personal mech is stumped by now.

Any other ideas here? Wheel bearings up front maybe (I did have it apart to change brakes/rotors, all seemed fine)

Wheel bearings would have to be fragged to do what you are describing. One more note on the harmonic balancer. They can shift on the rubber w/o looking bad or rotating under force. Ask anyone with a boat prop that runs fine until you apply full power. Balancers are meant to make up for harmonic vibrations in the crank assembly, basically a rotational shock absorber. If it is not up to spec, the vibrations you will get can be anything from minor to absolutely horrible. And it will be dependent on how much force (torque) is being applied. I had a race buddy that thought the motor was coming right out of the car on him. Know anyone with a motor sitting around? Swap out the balancer and see what happens. You have been through just about everything else......Some of the guys on these threads probably have one you could try...

I just rounded the corner on 153K, and hoping that my son's growth spurt slows up so I can keep it... I am wondering, can you put it on a dyno in a shop and start looking around at the heavy vibration speed? Nothing has the ground clearance of a stock T100...



jeff