Drive Shaft Vibrations Solved Step-by-Step

Huh. Only with Dakars evidently? I've attached snapshots of my AllPro expedition leafs, that I have loosely "pinned" through the leaf hanger with nyloc nuts rather than torqued all to heck. That in theory should allow more side to side movement than your cranked down Dakars, yet, I don't see much evidence of movement on mine. The type of side to side movement you are showing looks like the leaf wrap sliding out of place on its bushing, a manufacturing issue, more than a leaf bolt torque issue. UNLESS, on those Dakars, the type of bushing they are using needs to be compressed laterally and thus expanded, uh, in the "get fatter and fit tighter" dimension. Perhaps crank down those leaf bolts, the hangers are surprisingly flexible.

 

You are correct. Just gotta figure out if this is my cause of vibration and if it is, how to fix it.

 

So try this. Jack up your taco and set it on jack stands under the frame, just forward of the front leaf hanger. Get if far enough off the ground so that the rear wheels are hanging free (on my Taco, that's waaaay the heck in the air, but I don't have a vehicle lift so I use blocks of wood and jack stands and my hi-lift). BEWARE: really sucks when truck falls off hi-lift that far off the ground, ask me and my dented tailgate how I know..... With everything in the rear hanging free, get behind the truck and look closely at how things are hanging. Specifically, is anything tweaked to one side or another? Are the wheels and entire axle wanting to swing to the left or right? Pull a string along your axle to see if there's any deflection to one side or another. We usually mess with driveline angles in the up/down orientation, and trust the nuts and bolts to align things left/right for us. I feel you're sliding to one side or another, and in my experience messing so much with my truck, I've found that letting everything hang free, loosening the u-bolts and leaf hanger bolts, and retightening in a pattern (like wheel lug nuts) really helped everything "settle" into its intended place. Credit goes to my local lift shop on this one, by the way. They've learned from install experience that a "hanging torque" as they call it lets everything fall into place. Typical driveway mechanics (uh... that would be me ) don't have entire vehicle lifts and thus just do one side, then the other, and tend to contort the vehicle as we torque. Worth a try?

 

Thanks man, really good advice. I just hope I don't have to press a new bushing in. Hopefully I can try to pry the leaf back over the bushing to straighten it up, then go back and loosen and retorque.

 

If prying doesn't work, usual method of replacing / moving a bushing is using washers on fat side and a piece of pipe on other side, with bolt compressing the mess. Concept: remove leaf bolt, let hang on floor; using leaf bolt, stack washers against bushing side sticking out; on bushing "short side", use small section of pipe larger than diameter of bushing but smaller than mil wrap leaf spring; place pipe between leaf and stack of washers on far end of bolt, then thread nut. Tighten nut using two wrenches (one on either side of bolt), and pressure against stacked washers will force bushing "through" open leaf and pipe toward other side. Loosen and inspect as required to center bushing. Very old Baja trick, works great.

That said, a huge ass pry bar and cold beer also work.

 

Thanks for the advice man, much appreciated. Gonna get it done this weekend. And I'll update if it was the problem.

 

I have a 2011 2.7L AC prerunner and have been fighting the vibes like many here. Using the info from this forum I decided to build a DIY replacement CV joint shaft for the truck. I bought a drive shaft from Ebay off a wreck that fits my vehicle, purchased new U-joints, CV joint components, and had the rear drive shaft rotated and shortened 3 inches to accommodate the CV joint. I spent about $1K but that included all the tools (Press, Torque wrenches, angle gauge etc) and a lot of time to make it happen. After assembly I took the completed shaft to the driveline shop to straighten, balance, and install the shaft. The truck runs great with the replacement shaft, but I do have some small vibes with decel from higher speeds. The fabricated shaft was approx. .040 out of round after completion, the drive shaft shop corrected before install. For me this was worth the effort as I have a fully serviceable drive shaft and I can grease or easily replace the Ujoints, CV joints or carrier bearing if necessary. I really enjoy this truck and plan to buy it off and drive for many years. For grins the shop tech threw my original drive shaft from Toyota on his machine to check how straight it was. The stock shaft was out-of-round slightly more than my fabricated shaft. One piece of advice - if you have vibes and also have a local driveline shop, spend the $100-200 first to check your existing drive shaft for an out of round condition. The shop tech told me that he corrects many factory shafts that are out of round. Cheers.

 

Well crud. Thanks for the info bmrfm. Never considered the factory shaft to be at fault, unless there's physical and obvious damage (signs of candy cane scratches, obvious dents from impacts, etc). So many variables, so many potential causes. Thank you for your insight!

With your decel vibe, especially from higher speed (75mph down to 50mph) have some one check your front rotors for warping. Even while not braking, front rotor warp can shimmy under decel front end weight loading.

 

Very interesting

I am going through a similar issue with a truck that is essentially the same lift configuration

I'm puzzled though how your final angles show a 2.4 angle for the first shaft as compared to the zeroed TC , how is that acheived when at rest that relationship seems to be around 3 degrees ( 2.7 on my truck ) ? It seems to me that the CB end would need to be lifted higher than the stock mounting

Am I misunderstanding your results ?

Here is my angles currently for comparison


OK ,

had a chance to get some more accurate driveline angles today

This is parked on a level concrete slab

Front pinion



Rear is 4.50 degrees UP



Front section of driveshaft it 2.70 degrees off of square to the front pinion



Rear section of driveshaft is 0.30 degrees off of front section

 

Well that sure was an easy fix !
started getting vibes under acceleration from stop
figured the center bearing looked a bit sloppy but the U joints are still tight
got to this thread from a search on "center bearing" to get tips on changing it under the shadetree and read the Spicer Driveshaft Installation Instructions posted
problem solved
took all of five minutes

no vibes whatsoever

just put it back to stock
I put on overload springs to haul a trailer
it angled the pinion up
I figure as the center bearing wore, after a few thousand miles the vibes started becoming more noticeable
I removed the helper springs and could tell the difference right away
the axle is pointed back level now within 3* and in sync with the front half of the driveshaft

learned something new
a two piece driveshaft needs to have the axle pinion and front driveshaft at the same angle or it will be unbalanced
a one piece drivshaft can take any conbination of angles

learned that the purpose of a two piece driveshaft is to reduce the effect of rotational flex, critical speed they call it . the shorter the shaft the higher RPM it can do before it reaches critical speed and starts to flex and wobble

I probably could have just changed the center bearing and masked the problem for a while as wear would start transmitting through the driveline

now I will change the center bearing and check the U joints closer with the driveshaft out

thanks for posting that Spicer link !
saved me from blowing a driveline

 

thanks for that good info just what I needed to solve the mystery
evidently Spicer knows their business

 

Honestly I think you are best off using only a 0.5 degree shim, and then it should be no more than a few washers down to get you in line. Did you have the bed normally loaded in those measurements? Your angles come back almost 1.5 inches lower than mine, which is making your calcs a little tricky.

To test, before having to buy anything, you could pull those shims, flip the cb, and shim the cb down till your first shaft is between 2.0 and 2.6. From what I've calced that should be your sweet spot and tell you if we are on the right track. From there, we can tell whether the 0.5 or 1.0 shims will work best (the 1.0s may invert your first to second shaft angle).

I can't recommend running the stock cb flipped for long periods of time (5000+ miles) anymore, it seems to have chewed mine up, I now have over 1 degree of play in my cb. I have 3/8 (I think) rubber tubing shoved in the cb to firm things up, but my next move will be replacing that.

 

subdddddddddddddd

 

Just a quick question. I quickly scanned and didn't see it brought up, but if it has, smack me on the back of the head.

In the first post and in numerous others I see references to setting the center angle to near zero and trying to cancel the output and pinion u-joints, in effect trying to mimic a 1-piece. With my CB slop by doing the flip with an added washer I can do this. However, that makes vibes over 60 mph so I went back to stock. I noticed something when flipping it back.

These end joint yokes are 90 degrees to each other on my truck. That'll never cancel!

Wouldn't that instead mean the transmission and rear shaft should be parallel, and the angle from rear shaft to front shaft vs rear shaft to pinion be the same, so each section of driveshaft cancels vibration independently of each other?

Again, if I'm barking up the wrong tree, smack me in the head.

+1 to recommending against the CB flip. After I flipped it back it howled long enough to raise my blood pressure but has been silent ever since.

 

Quick questions, Have you done any measurements? Do you have shims on the axle? Any lift on your truck? How much cb slop do you currently have? This will help us get started.

To be clear the solution you are referring to seems to work on some dcsb 4x4s and ac 4x4s, but it is worthless on most prerunners and dclb 4x4s. You may be best off with the cb in the stock location, and shimming the rear axle to 0.5 to 1.5 degrees down of the first shaft, that was the way most of these trucks (maybe all) were set up from the factory. If you let us know your measurements and what kind of lift, if any you are running, we can try to point you in the right direction.

If you want the textbook on theory, I'm sure we can provide that too, although toyota's stock unopposed first shaft angle doesn't necessarily follow logic either (voodoo).

 

No measurements, as I have a fair amount of slop in the support bearing and know I should probably change it; no lift, no shims, stock 3-leaf springs gone flat. I don't really have much in the way of vibes - sometimes I can feel a little something, like a vrmm vrmm at 52 mph, or the signature 4cyl vibe going up a steep hill under cruise at 100% throttle in 5th at 60 mph, but it's not like my '09 that would shake the passenger seat at certain speeds. I did a CB flip to try to diagnose a sound that turned out to be the tires. I had wondered whether there was enough sag in the bearing rubber to give weird harmonics but as soon as I rotated tires the sound moved to the rear where it's more isolated.

When funds become available I plan on changing out tires (they're old), the center bearing, and all 3 u-joints (if I can find spicers that aren't $80 a pop) as preventative maintenance. That's when I'll measure angles. There's a mild intermittent shudder in the shifter in 5th gear that might be driveline but hasn't changed in 10k miles, although I read some other Toyota 5-speeds are known to have that particular quirk, as if the bass ackwards way they slide the shift hub away from 5th gear into the synchro magnifies small machining imperfections into perceptible vibration.

I suppose that kind of answers my question. I was just wondering why mine seemed to like something different.

Think Toyota really uses voodoo? I can just imagine some sunburned dude in a straw hat chewing on a piece of crabgrass holding high a $5.99 house broom decorated in glittered colored wood glue and magic marker guarding the exit door of the plant hollering at the top of his lungs at every truck passing by, "Keep thy passengers from shudders and shakes, thou accursed pickup!" Maybe the trucks with vibes left when he was on break.