*UPDATE* - It's Definitely a Drive Shaft Vibration...

Following this thread makes me wonder why after market parts companies couldn't go one step further and offer their lifts, especially the high end kits, with complete engineering that takes into account driveline issues like this. Its part of the reason that I chose a TRD Pro suspension for my truck, but I feel the pain in some of these posts. Trying to solve problems like this using random experimentation is just an exercise in frustration.

 

Yes true, but a fully engineered system that accounts for driveline angles should be possible. A Tacoma is a Tacoma

 

Good lifts do engineer and try to take the angles into account. That's why OME provides a CB drop kit, for example. But they have to make some assumptions. Lift up front, plate bumpers, sliders, load in the bed etc. all will change the driveline angle to some extent. They do the best they can.

 

That would take the "fun" out of it.

 

After experimenting with various intervals of CB drop using one M10 fender washer at a time I found that 5/16" drop gave me the best results. I actually switched out the 8mm OME CB drop spacer in favor of three of the fender washers as this combo was dead on 5/16" whereas the 8mm spacer is just a bit over 5/16". I didn't have enough washers to try anything over 5/8" so I wasn't able to test the drop up to 3/4" but I don't know if that would help me anyway. At just over 5/8" (the OME CB spacer plus three fender washers) I experienced vibrations at higher speeds (60 mph+) which I had never experienced before. I settled on using three fender washers as the 5/16" spacing eliminated all of my deceleration vibes and greatly reduced my takeoff vibrations. Right now I only feel a "shudder" on slow takeoffs between about 5 and 7 mph. If I accelerate hard I don't feel anything and overall the truck feels the most like it did on the factory suspension with this setup. For now I'm going to leave it alone for a few weeks and see how it feels. If I can get used to it I'll leave it alone. If not, I'll likely spring for a custom one piece driveshaft sometime later this summer. I don't plan on getting rid of this truck for a long time and I'm starting to think a new driveshaft is the best option for eliminating vibrations long term.

Another thing to keep in mind about drive line vibrations is that Toyota currently has somewhere around 3 or even 4 different rear leaf spring combos available on these second gen Tacomas. I was riding on the original 2+1 rear leaf packs for the first two years I owned my truck. I never once felt a driveline vibration (that I noticed) on those spring packs and the same can be said for the new recall 3+1 leaf packs I had installed in early May. However, once I added the Icon 3 leaf progressive AAL to my recall spring pack (with the overload spring installed) I noticed a slight vibration at takeoff. And while Icon states on their install instructions the 3 leaf AAL can be installed with or without the overload spring I have to imagine that the pinion angle will be different with 7 leafs versus the 6 I'd have if I had left it out. This is the reason some companies might recommend installing axle shims while others might like the CB drop kit. Every truck is going to react differently to a lift and other factors (like the age and condition of the U joints and the CB) are going to impact the drive line angles after the install. Who knows, if I had a brand new CB and U joints installed, maybe I wouldn't be experiencing vibrations? But like others have said, there are way too many variables for a suspension company to be able to recommend or even sell a one size fits all solution. If they did though, I'd gladly sign up for it!

 

However, Toyota gets it right when the truck leaves the factory. All I'm saying is that any given lift will produce a given drive line angle. The driveline angles need to be maintained, and the shims etc to do it along with the instructions could be provided. Maybe even a video. It's not as specific as some think it is. My understanding is that driveline balance is science, not art.

 

Bit the bullet and installed the 3° axle shims last night and removed the 3/8" CB drop. As of right now the shudder at slow take off between 7-10 mph is still there (more pronounced on an incline) but most of the other noticeable vibrations have diminished. I'm going to crawl under the truck tonight after work to measure my new drive shaft angles and decide if raising or lowering the CB will help. I'm hopeful that the shims plus an undetermined combination of CB spacers will get my measurements in that "perfect range" where the vibrations disappear but we shall see. I'll probably take measurements for a new one piece drive shaft while I'm under there as well, just in case.

One more thing I'd like to point out. The amount of noticeable vibration varies greatly from a full tank of gas to empty. The extra weight in the rear really does reduce the overall vibration I can feel. Makes me wonder if I shouldn't just load up the bed with ~200 pounds of sand bags and call it a day...

Anyway, stay tuned for another update tonight.

 

Yeah, it makes me still wonder if what you're feeling isn't just a little bit of tire bounce from the stiffer suspension. That's why a bit of weight helps. If at the end of the day, after measuring the angles and getting it perfect, either with shims or CB drop or both you still have the issue, I guess you'll know the answer to that question.

 

Ok, so I seriously can't make this stuff up...

As previously mentioned in post 68, I installed the 3° axle shims with the skinny side facing forward (as recommended by pretty much everyone) the other night. Well, last night I crawled back under the truck to measure my angles since I was still experiencing the take off shudder and some low speed vibrations. I was expecting to see the TC output angle and the pinion angle within .5° of each other and was fully expecting the two shafts to be off by more than 1°. And man do I wish that's what I found... Instead, here are my new angles:

TC Output: 0.0° (I calibrated my angle finder on this angle)
First Shaft Angle: 5.5° down
Second Shaft Angle: 4.2° down
Pinion Angle: 6° down

So yeah... as you can see, installing the 3° axle shims with the skinny side forward just doubled the difference between my TC output angle and the pinion angle.

At this point I'm not even going to mess with the CB drop but hopefully I can find the time to turn the shims around sometime this weekend. Based on what I've done and seen thus far, logic tells me that reversing the shims should result in a near 0° difference between the TC output angle and the pinion angle (ideal scenario) and that from there I can shim the CB to get the two shafts within 1° of each other. I'm not going to hold my breath but we shall see what happens.

In the meantime, if anyone wants to try to explain the math and physics going on with my truck, I'm all ears. I'm beyond confused right now and just about ready to say f*(k it and buy a Tom Woods one piece axle and be done with it...

 

Hang in there. You're solving the problem. This is totally fixable. When the numbers work, you will have no vibration.

 

I'm trying to remain positive, but man this whole thing is frustrating...

And for anyone who is late to this shit show (or noticed a change to the thread title), I updated the title of the thread and the first post in hopes to bring in more people who have experience chasing down drive shaft vibrations. I will continue to post replies as well as add updates to the first post for any newcomers.

Thanks again for all the help TW

 

OK, one more time with the diagram. Study carefully OP, it really is the key to figuring this stuff out:



By installing the axle shims "skinny side forward" you pivoted the differential downwards (rotated "counterclockwise" with respect to the diagram above) - wrong direction as you have correctly noted. Note the diagram shows the differential rotated up (clockwise) to match the angle at the jackshaft (true angle). Here's how to do it with only two angle measurements:

1) Zero out on the transfer case. Measure and record the "true angle" above at the jackshaft. Always use the transfer case as your reference/zero point.
2) Recheck/zero on the transfer case again. Now measure at the differential on a flat surface perpendicular to the driveshaft. Record the angle.

Note that you do not need to measure the angle at the rear shaft at all - only at the jackshaft and the diff.

The difference in the two angles is the amount in degrees you will need to shim the differential. Alternatively, or in combination, you can drop the carrier bearing to increase the "true angle" to match the angle at the differential. Note that by lowering the CB you will increase the angle at the jackshaft. But the angle at the diff will remain unchanged if you don't shim.

As the diagram notes once you get those two angles to match, the other angles at the rear shaft will be automatically be equal, the sky will open, unicorns will shower your Tacoma with rainbows and the ride will be vibe free (or at least driveline vibe free).


Just curious - have you tried a 3/4" spacer at the CB yet?

 

Have you replaced the carrier bearing already? Doesn't matter what your angles are, if your bearing needs to be replaced you're going to get driveline vibrations.

Edit** - Check out this thread https://www.tacomaworld.com/threads...uy-iedls-polyurethane-carrier-bearing.421410/

 

I feel your pain. Been there and done all that. I'll post from what I wrote from another thread.

The driveshaft I got back from Oceanside Driveline is still going strong and smooth as ever.

_____________________________________________________________________

https://www.tacomaworld.com/threads...ved-step-by-step.244535/page-29#post-11411428

"I gave up. Feels like over the past few weeks I've spent more time under the truck then driving it. In addition, my frustration levels have skyrocketed with each and every drive, finally reaching a point where the overall experience was testing my sanity.

• Brand new drive shaft made (previous owner had it modified with a disconnect for towing and wanted to remove it and replace the worn slip yoke at the same time). Helped a lot, but take off vibration was still there.

• Modified the rear trans mount achieving a 1.2* front joint operation angle, then shimming and rear end and moving the carrier bearing until both rear u-joints were within' .2~* of each other. Still had take off vibration, as well as highway vibration.

• Matched transfer case and rear diff flange angles, dropped carrier bearing until both shafts where the same angle, then fine tuned from there. Nope. Still vibration.

• Shot the pinion angle up to match the front shaft, made the 1st and 2nd u-joint operating angles the same. Negative.
• Silicone in the carrier bearing. This made a noticeable change, but also made vibrations much more pronounce when something wasn't right.

• At this point, something should have worked. Move one component to fix something, it compromised another. Constant battle between low end vibrations, or high speed vibrations. I can see on a stock vehicle making it work because angles are less, but once the rear pinion and transfer case flanges are pushed further away from each other, the stock driveshaft can't deal with the drastic changes.
• As far as some people experiencing vibrations and some not, I think it's not so much the vehicle, but rather the persons perception of what vibration is. My g/f and friends have driven and rode in my truck and didn't notice a thing. I'm not convinced that identical trucks with identical suspension setups will show different vibration characteristics.

None of my previous vehicles have EVER had driveline problems like this Tacoma has. Thinking back, all of them had double cardan joints at the rear shaft. So this morning, Oceanside Driveline is picking mine up and making it a proper 4 joint shaft.

Thanks to everyone for sharing all their knowledge. I learned a lot and it helped me understand exactly what's going on and creative ways to try and tackle it. I'll report back, hopefully tomorrow when vibrations are a thing of the past and I can enjoy driving the truck once again."

 

I have not, and with the shims installed it's likely I never will. That and when I had no shims installed and 5/8" of CB drop the vibration was terrible on the highway. I can't imagine additional drop magically making the vibrations disappear, especially with the 3° difference between the differential and the transfer case output...

Nope, and I'm not inclined to do so. I didn't have any vibrations before the lift so the CB should be more than capable of doing it's job if I can get these angles within spec. Besides, if I can't solve the vibration with shims and a CB drop kit, I'm going to ditch the CB all together when I buy a custom one piece rear drive shaft. I'd rather put all of my money into a new double cardan one piece shaft than a new CB or a replacement poly CB bushing.

I hear you man. And if reversing these shims doesn't get my TC output and pinon angle near 0° you better believe I'll be researching replacement drive shafts!

 

Alright, I give up...

Tonight a friend of mine helped me reverse the 3° axle shims. After we were done and the truck was back on the ground I took some new measurements.

TC Output: 0.0° (I calibrated my angle finder on this angle)
First Shaft Angle: 5.7° down
Second Shaft Angle: 6.2° down
Pinion Angle: 0.7° down

As you can see with the shims reversed I got the TC output angle and the pinion angle below 1° and the first and second drive shafts are within .5° of each other. I was really hoping for the difference between the TC output and pinion angle to be much closer to 0° but it is what it is... Anyway, with this new setup my takeoff vibration is still there and now I have a truck shaking vibration at 30 mph both when accelerating and decelerating. This combo might have resulted in the worst vibrations I've experiences thus far and it was incredibly disappointing. I even tried to add the 8mm OME CB drop kit and when that didn't help I took it as far as I could with my fender washers (5/8") and the truck still shook horribly around 30 mph. At this point the 3° axle shims are coming out first thing tomorrow and I'll be going back to the 8mm CB drop for the time being. That combo gave me the best results I've had thus far but it's still far from ideal.

In the meantime I'm going to reach out to two different local drive line shops to get estimates on a custom one piece double cardan shaft. I hope to have a new 4 joint drive shaft installed within the next week so that I can put these awful vibrations behind me and get back to enjoying my lifted truck.

Thanks to all that have tried to help me with this issue and while I know this whole drive shaft thing is a science and that if I messed with enough combinations of shims and CB spacers I could eventually cure the vibes but with my OEM drive shaft and CB being 7 years old and having 65K miles on it, it's just not worth the time and effort for me to continue down that road.

 

I too have been battling this vibration since I lifted my truck with 3" procomp and aal. I have tried adjusting the center support bearing up, down, flipped all still leaving a different vibe each time. I went and bought a degree finder just like badger said in his first example and installed 2.5 degree axle shims. That took the 20mph vibe away and reduced the take off but it's still there. I am really thinking axle wrap is the cause and considered putting on some traction bars. Another detail that points toward axle wrap is when I brake hard and the truck stops I feel a clunk in the rear end as if the suspension has settled back down. I haven't found a lot of information on what traction bar setup is the best.

 

Has anyone else noticed that the 2016 4 runners come from the factory with traction bars?

 

I did not get a new drive shaft. The vibration is all but gone with nothing more than a 5/16" CB drop installed. The only time I notice it is from a slow start on an incline. I don't have any vibrations at speed and on level ground I rarely feel the takeoff vibration anymore. At this point, it's good enough for me to live with, especially since I'll likely be selling or trading my truck in within the next month or so (going to order a 2017 when they become available).

 

Glad to hear you got this figured out. Did you by any chance take note of your DS angles in the final set up (5/16" CB drop)? Interested to see what they are.