Drive Shaft Vibrations Solved Step-by-Step

I might be barking up the wrong tree here, but that sounds like it could be the front diff needle bearing going bad. Assuming you have 4WD, do you know if you have an ECGS bushing installed in the front differential?

 

It probably doesn't, but when I put it in 4WD it doesn't go away.

So drove to work this morning 40+ minutes and vibes we're pretty bad. Felt like a constant vibration under my seat CB location. I'm just going to flip the CB back to how it should be without the OME drop kit, see how that works. About ready to trade this POS in. Should of kept my 2016 Mustang GT

 

I seem to remember that there should be a slight angle at the first u joint out of the transfer case? My memory says .8 or slightly less, but never 0? Maybe that's where the vibe is. Looks like everything else is good. I do remember that vibe hunting is a SOB! Good luck and hope this helps.

 

Taking your numbers and plugging them into my calc sheet:

... here's what I'm getting. Correct me if I'm wrong.

theta_1 - transfer case flange
- 0.0 degrees (zeroed on TC)

theta_2 - forward half of driveshaft
- 1.9 degrees

theta_3 - rear half of driveshaft
- 5.6 degrees

theta_4 - rear diff flange
- 2.0 degrees

Using these measurements, you get the following u-joint working angle values.

delta_1 = | theta_1 - theta_2 | (transfer case u-joint working angle)
- Acceptable value: =< 0.5 degrees
- | 0.0 - 1.9 | = 1.9 degrees
- delta_1 on my truck, for reference = 1.9 degrees

delta_2 = | theta_2 - theta_3 | (center u-joint working angle)
- Acceptable value: delta_3 +/- 0.5 degrees, and no greater than 3.0 degrees
- | 1.9 - 5.6 | = 3.7 degrees
- delta_2 on my truck, for reference = 2.0 degrees

delta_3 = | theta_3 - theta_4 | (rear diff u-joint working angle)
- Acceptable value: delta_2 +/- 0.5 degrees, and no greater than 3.0 degrees
- | 5.6 - 2.0 | = 3.6 degrees
- delta_3 on my truck, for reference = 2.3 degrees

delta_dev = | theta_2 - theta_4 | (difference between forward half of driveshaft and rear diff flange alignment)
- Acceptable value: ~ 0 degrees
- | 1.9 - 2.0 | = 0.1 degrees
- delta_dev on my truck, for reference = 0.3 degrees

The only issue I can see is that the center and rear diff u-joints (delta_2 and delta_3) are slightly exceeding their maximum operating angle of 3.0 degrees. Not by a huge amount, just by ~20% or so. Also, the transfer case u-joint working angle (delta_1) is a little high. These deviations are pretty minor, so I don't think they are the cause of your problems.

The numbers you posted make me think something other than driveshaft angles are responsible for causing your vibes. Do you think one of your driveshaft bolts may have worked loose, or maybe the driveshaft itself is out of balance?

 

When I get home I will double check the hardware. I really appreciate the help though. Hopefully I can figure it out or something. About to just bite the bullet and get a Tom woods. Lol

 

Keep us posted. If you don't have any loose bolts on your driveshaft, and don't want to pull it out to have the balance professionally checked, then I think the Tom Woods single piece is your only option.

 

Hardware re-torqued. Flipped the carrier bearing back to OEM with out OME drop kit. And it's some what manageable and not too annoying so yeah I'm not putting any more effort into this drive shaft. I really do appreciate helping me with the calculations and what not. Just Gunna pull the trigger on a Tom woods probably after the New year.

 

Reviving this thread in search of some help.

I did my measurements following the procedure and my results are:

theta_1 - transfer case flange
- 0.0 degrees (zeroed on TC)

theta_2 - forward half of driveshaft
- 2.7 degrees

theta_3 - rear half of driveshaft
- 3.7 degrees

theta_4 - rear diff flange
- 2.0 degrees

Using these measurements, I get the following u-joint working angle values.

delta_1 = | theta_1 - theta_2 | (transfer case u-joint working angle)
- Acceptable value: =< 0.5 degrees
- | 0.0 - 2.7 | = 2.7 degrees

delta_2 = | theta_2 - theta_3 | (center u-joint working angle)
- Acceptable value: delta_3 +/- 0.5 degrees, and no greater than 3.0 degrees
- | 2.7 - 3.7 | = 1 degrees

delta_3 = | theta_3 - theta_4 | (rear diff u-joint working angle)
- Acceptable value: delta_2 +/- 0.5 degrees, and no greater than 3.0 degrees
- | 3.7 - 2.0 | = 1.7 degrees

delta_dev = | theta_2 - theta_4 | (difference between forward half of driveshaft and rear diff flange alignment)
- Acceptable value: ~ 0 degrees
- | 2.7 - 2.0 | = 0.7 degrees

Can someone you help me understand if I'm within the parameters?

 

Sure thing.

Delta_1 looks a little high, but may not cause any problems. Removing a CB drop kit or flipping the CB upside down should get this closer to 0.5 degrees, but this will affect delta_2 and delta_3.

Delta_2 and delta_3 are pretty close, which is good.

Delta_dev looks pretty close to zero, which is also good.

Are you getting any vibrations with these angles?

 

Not sure if vibrations are coming from wheels out of balance or the driveshaft. I do notice vibrations when pulling my travel trailer out of a complete stop on slightly aggressive acceleration. I believe this is a sign that there are indeed vibrations coming from the driveline correct?

I don’t have a CB drop. Everything is OEM on the rear except for ICON RXT set in option 1 and longer shocks.

I know that Tacomas are prone to vibrations and are not the smoothest so not sure if I’m expecting something that isn’t possible.

Thank you for your reply btw!

 

If that's the only time the vibrations are super noticeable, then I'd bet axle wrap is the cause. If the vibrations are present in varying degrees at all times, then I'd say your at-rest/unloaded driveshaft angles are out of whack.

 

Wanted to share as this might help someone out there. I did some more reading and learned about the old school string method to make sure my CB was centered.

Basically consists of running a nylon string from the center points on each end of the driveshaft to show where the center should be located (side to side not angles).

Found out it was off center and proceeded to center it. By just doing that slight adjustment my in cabin vibrations from just driving around normally virtually disappeared. It’s crazy how sensitive the system is and how something that seems that simple influences the overall driving experience of the truck.

I think I’m finally pleased with how everything feels now.

 

Question, just for clarity. To get the rear pinion angle, are you zeroing on the transfer case and measuring the rear differential/pinion flange or are you zeroing on the 2nd shaft and then measuring the differential/pinion flange?

 

Zeroing on the 2nd shaft then measuring differential/pinion flange.

 

With this thread starting nearly 10 years ago, where should I start to get my head wrapped around this. Trying not to reinvent the wheel, but want to be knowledgeable enough to fix the angles on my own. Been having the same issues ever since lifting 2.5” on my 2022.

 

Not to toot my own horn here, but I think my procedure is pretty thorough.

 

What specs would you use if you never took measurements prior to lifting?

 

These are the values I pulled from the Spicer site, but it seems my truck was outside the acceptable range when stock.

 

I have a helper spring in the rear with some 2 degree axle shims. Last night I measured all of my angles (relative to horizontal) and found the following: TC = 2.9 down, 1st shaft = 5.1 down, 2nd shaft = 5.0 down, Pinion = 3.8 down. From these measurements I have the working angles of 2.2 , 0.1 , 1.2. At this point it looks like I have two options. 1. Rotate the pinion up another degree to be match the first and third working angles. 2. Rotate the pinion down to match the second and third working angles. Is one or the other preferable?

 

Following up on this thread with my own experience, for what its worth:

After installing a roughly 2" lift for the front and 4" lift for the rear, a carrier bearing space (~.5"), and a 3 degree pinion angle shim, there was a takeoff vibration from about 5-15mph. Relatively minor, so I tried to ignore it.

Now that its warming up outside I decided to tackle this problem.

From reading on the topic, it seems like there's two schools of thought (feel free to correct me if this is wrong):

1) Try to align the two driveshafts and pinion as close as possible, so they are all in a straight line.
2) Try to align the pinion, front drive shaft, and front diff. The angle between the front diff and front driveshaft should be less than 1 degree.

I went under the truck yesterday and measured everything according to OP's direction and I was very close to option 1. After throwing everything into a CAD model, I determined that adding about 1/8"-3/16" of spacers under the carrier bearing will nearly put the two driveshafts in alignment, and the pinion will be off from those by about 0.5 degrees.

So, I added a pair of 1/8" washers under the carrier bearing and tested it out. Those takeoff vibrations are almost gone, only noticeable between 5-10mph and very minor. Today I tried adding a second set of washers and it appears to have made the vibrations slightly worse, so I'll be removing those and calling it good enough for now.