1999 Xtra Cab 4x4 5th gear/driveline vibrations

I'm at the end of my rope with this problem. I've searched forums high and low for over 2 years and can't seem to find any definitive answer on this.
I have a 99 Tacoma Xtra cab, all stock, no lift, that I have been plagued with a vibration with for a couple years now. There's 166k miles on the truck.
The vibration feels like it is in the driveline. It ONLY happens in 5th gear. The minute you go to 4th its gone. I've tried different pedal pressures and speeds and can't get it to occur in any other gear. The vibration is significant enough that it buzzes the whole cab, causing the dash to buzz and vibrate and my sunglasses on the dash to buzz against the windshield. The vibration generally goes away as I get up over 60 or heavy on the gas. But light pedal and 2k RPMS or less and it's buzz buzz buzz and shake shake.
I just finished having the whole driveline rebuilt by Driveline services of Portland. New OEM carrier bearing, new flange, new yoke, new U-joints and I honestly couldn't even find anything wrong with the driveshaft when I removed it. Looked perfect. Driveline services said the double cardagon (CV joint) was fine and spun it up to over 3000RPM and no vibration. However, while I had the driveshaft off I drove the truck around in 4 wheel drive and in 5th gear and no noise and no vibration.
I've read posts all over the web about this problem, people rebuilding drivelines and rear ends and still having the issue. At this point I am beginning to suspect that 5th gear may be the issue but of course that is a ton of work and I would love to have someone experienced with this issue chime in before I drop transfer case and transmission.

 

bump

 

Sounds like something in 5th gear inside the transmission to me...

 

My 96 has the same problem. I've had it for a few months and when I first got it the vibration would rattle your teeth at around 50 mph. What I have found through researching forums is that it is caused by drive line misalignment. I suspect the misalignment is caused by the rear springs breaking down. They are known for being weak and settling, even to the point of being flat or having negative arch (arching up instead of down in the middle). The only "fix" I've found is to shim the carrier bearing down. Get a bunch of washers that will fit over the 10mm bearing mount bolts. Remove the bolts and shim the bearing housing down about 1/4 inch. 3 washers per bolt is about 1/4 inch. Take it for a drive and see if it cures the vibration. If not, try a 4th washer on each side and drive it again. If you need more than 4 washers you will need longer bolts. I have 3 washers on mine and though it still vibrates, it isn't nearly as bad. I haven't had the chance to play with it to see if I can find the sweet spot yet.

 

From the OP,s description , I am going with an engine related issue . When was your last tune up and throttle body cleaning ? spark plugs and wires, fuel filter etc etc ?
Judging by your description , you have a manual transmission .
It doesnt take much to feel an engine missfire when you are in overdrive .
I would suggest dropping by a reputable transmission shop for a " FREE " road test . Those guys diagnose this stuff day in and day out every day and they dont charge for a road test .


lets look at some Vibration diagnostics .
I beleive there are at minimum at least 12 different vibration issues associated with the Tacoma and all the vibrations / shudders get mixed into the same pot leaving members scratching their heads .
Have you greased your driveline ?http://www.tacomaworld.com/forum/tec...rks-total.html
Do you know how to grease your driveline properly http://aftermarket.federalmogul.com/...%20FAQ%27s.pdf
Have you checked your carrier bearing https://www.tacomaworld.com/threads/how-to-replacing-carrier-bearing.260283/
Does the truck vibrate in park or neutral and does the vibration change with accelarator pedal ?
Does the truck vibrate while holding the brakes and hitting the gas - Automatic ?
Does the truck vibrate in neutral at a stand still ?or coasting in neutral ?
Does the truck vibrate in 4x4 ?
Does the truck " Only vibrate " from 1st to 2nd gear ? https://www.tacomaworld.com/threads/vibration-when-accelerating-from-stop-anyone-fixed-it.300155/
Does the truck only vibrate in 2 wheel drive ?https://www.tacomaworld.com/threads...differential-bearing-vibration-thread.152173/
Does the truck vibrate with the serpentine belt removed ?
Does the truck vibrate cold or hot ?
Does the truck vibrate if you select neutral and coast to a slow roll without using the brakes ?
Does the truck vibrate as you are braking ?
Does the truck vibrate with weight in the truck or empty ?
Does the truck vibrate while upshifting ? Have you checked your trans fluid ?
Does the truck vibrate while downshifting ? Have you checked your trans fluid ?
When was your last transmission fluid service ?
Now that you have a lift kit installed the truck vibrates . Did you cancel your drive line angles ?
Have you looked at the condition of your tires ? Toyota says to rotate every 5000 miles .Tacoma tires must be road forced balanced using the Haweka adapter on the tire machine tsu00296.pdf
When was the last time you rotated your tires ? Are you using LUG centric aftermarket wheels ? have you considered " HUB centric rings " http://www.amazon.ca/s/?ie=UTF8&key...vptwo=&hvqmt=e&hvdev=c&ref=pd_sl_7ybe1f1pby_e
Have the balance weights fallen off the tires ?
The proper and only way to test for bad universal joints is with the driveshaft removed . You cant tell if the universal joints are seized or tight spots with the driveshaft on the truck . You may see play in the universal joints , but you wont be able to properly check the u-joints without removing the driveshaft .All it takes to create a vibration is one seized universal cup and there are 4 cups within each joint .
With this said , you cant tell if that cup is seized with the driveshaft connected .
Removing the driveshaft and manipulate each universal joint by hand from side to side feeling for tight spots as you go is the only way to check for bad u joints
If you beleive its bad motor mounts or transmission mounts , grab a big pry bar and pry at the mounts to see if the rubber is torn or weak .

CANCEL DRIVELINE ANGLES http://www.tacomaworld.com/forum/2nd...tion-free.html

 

May not be the problem, but it's cheap to try and just may work for him... sure helped my 96.

 

He said no issues driving in front wheel drive so that would rule out engine and transmission for the most part. I vote on the harmonics related to driveshaft angle as pofarm stated. What I don't see about the shimming of the carrier bearing is if it was caused by weak springs, shimming would seem to cause the off-set to be greater NOT less.

 

Dunno. I do know that my springs are in real need of replacement (de-arched) and shimming the bearing helped.

 

Sorry it took so long to respond. Haven't been on the forum much. However, pofarm appears to have nailed it. And thanks gearcrusher for the very long and detailed post. I described in detail in my original post the parameters of the vibration and what I had done so far and nothing fixed it.

However, after reading pofarm's post, I realized I could easily investigate his theory with nothing more than a little compressed air. I installed airbags in the rear of my truck back when it was new and it only took a dirtbike and a small box of tools to make it sag. Lately, the airbags have just been flat and unused but I thought hey I'll just air those back up and get the ass end up a few inches. Sure enough, the vibration is gone.

The problem with my airbags is the suspension is pretty stiff when they are aired up and bounces around a lot. So now I'm wondering, should I replace leaf springs and are there any recommendations on that? I will certain check out the links that gearcrusher provided as well.

 

so your driveline was just binding at the u-joints? but you said this only happened in 5th gear. im not doubting you or anything, in fact it makes perfect sense because that's the very reason CV shafts were made. u-joints would bind at extreme angles. front axle 4x4s with u-joints will vibrate insanely at high speeds and sharp turns. I just want to make sure you're not forgetting something and have another issue happen down the way, ya know?

I heard someone fixed their axle wrap issue by putting some u-bolts on the rear half of the leaf springs. I wonder if that wouldn't fix your situation as well. if im not mistaken, it would prevent the pinion from tilting down, causing the bad angle and vibration.

 

My Tacoma suspension is pretty much stock except for helper airbags on the rear axle. The driveline isn't binding and if anything, the rear end sagging would decrease the driveline angles and raising it with the airbags is making the angles more extreme. But the angles aren't anything much at all, maybe like 5-10 degrees? The driveline is all rebuilt with all new parts except the CV which they said checked out fine to 3000RPM like I mentioned above.

As far as axle wrap, I thought axle wrap caused a popping sound on take off. Are people suggesting the axle wrap causes driveline vibrations?

I honestly don't understand what's going on at all and why raising the rear with airbags is making the problem go away. It's only increasing the driveline angles. I also don't understand profarms fix for his if it's caused by sagging suspension in the rear. If the axle is sagging and now closer to the frame, then you'd think you'd want the carrier bearing higher, not shimmed lower, to get the angles back to original. None of it makes sense to me

All I know is it's stopped my vibrations pretty much. I may let the air out of the bags again and see if it immediately comes back.