Vibration after 3" lift - Carrier bearings? Where to start?

Hey guys.

200k miles on the truck. No noise or vibration before the lift. Put on the full 3" OME lift using the add-a-leafs in the rear. Did the diff-drop in the front. New 33x12.50x15 tires as well that had been balanced. Slowly drove the truck to the alignment shop.

I'm getting significant vibration from 7-22mph and then noise 55-65mph. It's only under normal acceleration, so I don't think it's a tire balance issue. Clutch seems fine. Don't think it's axle wrap. I crawl under and wiggle everything and nothing noticeable. I get some movement around the center carrier, but not slop. Just resistance movement around the bushing.

I finally got a chance to look at it deeper yesterday and after taking it on a quick drive including a few miles on the freeway, I pulled off and crawled under the truck looking for heat. All of the driveline, u-joint, axle components including the diff were cool to the touch except the axle carrier was hot. This is the part I'm talking about:

It was hot to the touch and made me wonder of course about the new driveline angles. I just drained the fluid and the diff was full. It's mud colored fluid, but seems fine. Wasn't stinky.

After research it sounds like a center carrier drop is a good idea. Do I need to worry about shimming or adjust the pinion angle on the axle for only a 3" lift? Right now I'm most concerned about whether I have a component like the ring & pinion about to grenade if I don't do something immediately.

Any suggestions on how to pinpoint the issue? I'll probably jack-up the rear end and put it in gear and try to replicate while watching the drivetrain.

 

I'm not a tech by any means, but after adding my 3" lift I did the ECGS needle bearing swap. The whining noise and "hot smell" went away. I do also have the carrier-bearing drop, so I know I'm not answering your question directly....

Interested in the responses here from those more knowledgeable than me.

 

Not sure if it matters, but I also replaced the steering rack when I did the lift due to slop on the driver side.

 

Ah yes, the wonderful driveline vibrations. First off, you're not going to grenade your rear diff - the rear u joint will go out first if anything.
Some people have good luck with the carrier bearing drop, I found it helped some but the higher speed (60-65) vibrations are still there. I still have the Streetacos carrier bearing drop bracket (1-1/4") from @BeefedTacos. If you are interested I will sell it to you, they are hard to get due to fabrication time.
I had good luck with a 3* axle shim, to aim the pinion of the rear diff up towards the carrier bearing.

 

Thanks for the quick reply drr. I agree that it must involve the driveline angle, so drops and shims make a lot of sense. I can't imagine something being worn out, so it must be angle related. I'll take you up on the drop bracket. I'd like to hear more about your shim solution as well. PM on it's way to you.

I'm going to refill the pumpkin and let my kid keep driving it to school and work since it's only about 5 miles away and no freeway. I can get the drop installed and maybe shim the axles next week.

 

I'll put this up here, as this question comes up fairly often and it may help others out.
Driveline vibrations are caused (in part) by unequal u joint angles. Generally you want to have a minimum of 1 to 1.5* in a u joint so that it will lubricate itself as it goes through its full range of motion, and no more than about 7* of angle in any single u joint (not a problem with our trucks and ~3" of lift). The angle of the u joint on one end of the drive shaft must be cancelled out by an equal angle at the other end of the driveshaft (this is for a single piece driveline, but the rule applies to all u joint applications).
For a two-piece driveshaft like on the Tacoma, there is a double cardan joint just behind the center carrier bearing that is basically two u joints in one. Because of this arrangement, we have a relatively low-angle driveshaft between the transfer case and carrier bearing, and a higher angle shaft between the carrier bearing and the rear differential.
There are two schools of thought for "cancelling" the u joint angles for a setup like the Tacoma. The first is what Dana Spicer (the driveline manufacturer) recommends for their applications, which is that the pinion should be at the same angle as the front half of the driveshaft, like this:

To achieve this arrangement, you can either adjust the pinion rotation with axle shims to match the front propshaft, or you can lower the carrier bearing so the front propshaft matches the pinion angle (this is what the Streetacos drop bracket does). However, this general case does not include a double cardan joint.
The other way people do it is leave the carrier bearing along and shim the rear axle to point the pinion at the carrier bearing (or close to it). This puts all the angle in your driveshaft into the double cardan joint, which is self-cancelling because it is two u joints rotating around a center ball. Here's the basic idea (obviously a little different for our trucks):

(C.V. means double cardan joint)
Personally, I don't really like having shims under my leaf packs, they tend to rotate around and they can increase axle wrap. There are also many other issues that could cause driveshaft vibrations, including worn out u joints, worn double cardan (rarely happens), tires out of balance/out of round, worn out motor/transmission mounts, etc. I would go through and check as many of those things as possible before playing around with driveshaft angles. Also, buy one of those cheap digital magnetic angle finders and get under your truck and measure all the angles. Draw a picture and write down what all the angles are, that was you can tell if any changes you make are going in the right direction.
When you check the u joints on the driveshaft for wear, you have to remove the driveshaft from the truck to actually check them. You won't feel any movement in the u joints if you just get under the truck and jack the driveshaft up and down (unless they are so bad they're about to fail). Take the driveshaft all the way off the truck (careful the slip yoke doesn't fall out) and move the u joints through their entire range of motion. Any wobble, clicking, crunchy spots, noises, or anything other than super smooth movement and you should replace them. If you don't feel like springing for OEM, get the Napa heavy duty greasable ones ($20). All the u joints for the front and rear driveshafts on Tacomas (except the double cardan) are the exact same part.

Here is some additional information if you really want to get into it:
http://www.4xshaft.com/driveline101.asp

 

Vibes after lifting (2" & up) in rear is common because the relation of rear diff. pinion to drive shaft changed, mine was a solid 3" lift & corrected vibes by dropping CB 3/4" & it all went away...

 

Thanks for the confirmation. That's what I'm going to do.

 

Dont worry about your rear diff being hot after a long drive, its totally normal. The ring and pinion create alot of heat!

 

One thing I always do before removing a drive shaft is to mark the location with a white paint pen.

If the rear slip joint happens to come apart on you, don't panic.
Just reinstall it , with all joints lined up (in phase).
Some times , you can eliminate ate a vibration, by turning the drive shaft in 1/4 turn increments.

Unbolt the shaft at the flange after marking it's present location, and turn it one bolt hole , remember there are 4 bolts, each represents 1/4 turn.

 

Slip joint has a boss spline so it will only go on one way.

 

Had same prob. after mine. Played with dropped C.B. and rotating shaft in case I had gotten out of phase.......angled shims made it all go away. 100K miles ago and all is fine but I don't bounce off rocks.

 

Fixed my vibrations by dropping carrier bearing 1/2" by the way.

 

Devinzz , thanks for that bit of info, not all are this way, and it never hurts to err on the safe side.
Thanks again.

 

Thank you DRR! I'm drafting off the rear bumper of GR8Dane and appreciate him raising the issue.
My slight remaining vibration goes away when fully geared (I have AllPro Expo springs), but reappears when running light.
I'm off to the garage....

 

Axle shims are the solution. A carrier bearing drop will reduce vibration but your pinion angle needs to be adjusted or you'll have premature u-joint failures at that flange.

 

Shims are ONE way to fix vibes & dropping CB is another...Some have even flipped the CB with good results....

( Tho' more work, personally I'd do shims but figured I'd try dropping CB first & got lucky with a 3/4" drop, no vibes thruout vehicle range of speed...

 

http://youtu.be/f1m-Fh5kiRU

 

Nice vid but the environment for testing is too "sterile"...

In this vid (skip the first 50 sec. ) although you can't see Ujoints but you CAN see all that is happening with rear susp. & driveline with flexing & gyrations ...

https://youtu.be/uCeK7Sb0poQ?t=2