Driveshaft Angles

One thing that I've learned from reading is that before torquing the bolts of the center support bearing (CSB), it's important to make sure it's dead center. If not, then a compound angle will be introduced into the driveline potentially causing unwanted vibrations. My CSB could move about 3/8" left or right.

One solution is to measure using a string.

I tied a string around the zerk at the rear axle.


Then pull the end of the string so it's dead center with the zerk at the transfer case.


Now observing the CSB, use the hole in the bottom as a guide to find centerline, and finally torque bolts proper.

 

That rotation between Ujoints Will cause lot of vibration. Correct that firts of all

 

The carrier bearing is not centered vertically in it's housing, it's offset to one side. Toyota reinstalled my carrier bearing after the frame swap upside down, and there were all kinds of vibrations. The shaft would flop around on hard acceleration and almost hit the gas tank. The bearing assembly has one side with 2 holes and the other side has 1 hole. My carrier bearing is now installed with the single hole facing down.

 

I will have to check this out and see how mine is installed. Mine is aftermarket. I replaced it almost a year ago thinking it might fix the vibrations. That was before I had looked into anything like angles lol

Thanks for the post about the string test too. That's a great idea. I'm gonna try and do it tomorrow and see how it looks. As for the phasing being lined up, I'm not quite sure how to fix that. I'll check with my mechanic friend I guess I'm sure he'll know

 

Okay. I'm not 100% certain but from what I remember, if you pull the yoke off the shaft, I think it has a master spline. Despite that, I think it can only go in one of two ways. There is a reason for this which is discussed in one of the Dana DS manuals. That said, I agree from your picture that yours looks a little off, not sure why.

I reviewed some photos of mine when I had it out and the first shaft indeed has the yoke in phase.

Kind of a crappy picture, but you can see it. It's also very good practice to index and mark with a paint pen before performing DS maintenance, so that you can put it back in exactly like the factory had it.


@Sandman614 's comment about the center support bearing is very good. I know you said yours is aftermarket. From your photo it does look like yours may be upside down, if it was a factory clone.

In this photo, you can see how the mounting ears are not centered on the CSB bracket, which is why installing upside down would change the angle of the first shaft.


Again, from the photos, yours may be inverted. It's very easy to fix too, unbolt, flip and bolt back in, make sure CSB is centered using string method.

When the CSB is in it's proper orientation, it has an arrows imprinted on the bottom of the bracket.

Those arrows should point to the front of the truck as illustrated here:



Another thing to check for is balance weights, usually two one at each end of the shaft, AFAIK. They are flat and rectangular, and can be seen if the first picture of this post. One of mine was almost ripped off. I had the DS shop tack weld it back on for me.

 

Thanks for the great post crom. I can clearly see that your phasing is perfectly lined up, mine is slightly off. I also need to check to see that the CSB arrow is pointing the right direction. I flipped the CSB last night (now the two holed side is facing up) and the vibes seem different...But they are still very much present. So I'm sure that helped but I likely have other issues that are the main source of the vibes. Also, I need to check if I have weights...I don't recall seeing any but then again I wasn't really looking for any. I will check when I get off work today and post my findings!

I appreciate the help and advice from all so far.

 

Has anyone measured the factory angles? If so, can someone post or link them?


I used this as a simple guide to determine operating angles. Below are the angles based on my measurements using an electronic protractor.

There seems to be some misinformation in that video and it may be because its referencing a Tundra. The first operating is no way going to be close to < 1* for a Tacoma ( I think this was pointed out in an earlier post). Mine is around 4.6* and this is a factory measurement.


http://spicerparts.com/calculators/driveline-operating-angle-calculator


The other issue mentioned above is the rear pinion angle needs to match the coupler shaft angle. To do this on mine as an example, the rear pinion angle would need to increase 2.5* or in other words, the pinion shim would go in backwards and to move the pinion down. This may actually need to be done, but by doing so, you might be surpassing the MOA, maximum operating angle for the ujoint.

I am going to re-measure with a different inclometer to see if the protractor has similar results.

 

@Crom nailed it with the first post. Get the pinion output and first shaft parallel, and you're golden. Either shim the axle or drop the carrier bearing - or both.

Yes you can - by adjusting at the carrier bearing.

I'm at work and don't have my measurements handy but a 3/4" spacer at the carrier bearing got my angles within a degree - parallel enough Dakar springs and no axle shims. Every truck is going to be different - that's why you gotta measure the angles. And it will change at the pinion angle over time as the springs bed down.

 

Thanks for the reply. However, when you increase the angle of the coupling shaft by shimming the carrier bearing, you are going backwards and getting farther away from parallel. One would have to raise the carrier bearing to lower the coupling shaft angle and increase the rear driveshaft angle.

I ran some Solver scenarios in Excel. You cannot get to a parallel scenario by shimming the carrier bearing. Only if you could raise the bearing would it be possible.

To get to a parallel scenario on my setup, I would need a 3.9* axle shim. This 7.9* angle would place the ujoint beyond the maximum operating angle.

 

Adjusting the carrier bearing does not affect the angle at the pinion, only the angles of the shafts. That is why CB drops work - for some of us anyway.

 

Yes, when you drop the carrier, it increases the angle of the front shaft and gets you farther away from being parallel with the rear pinion angle.

You have no vibrations?

Can you post your angle measurements?

 

I can't speak to your solver calculations. You bring up an important detail the relationship between RPM and operating angle.

Shimming the CSB down makes the u joint OA nearest the transfer case worse.

Based on my experience, I seriously question whether Tacoma's rolling off the dealer lots have their OA in spec for u joint nearest transfer case. Mine is almost 5° on a fresh rebuilt shaft using factory spec parts.

 

Ok guys tell me if I'm wrong but doesn't he @dpi need to take his CB up to match pinion?? Can't he flip CB bracket since it doesnt sit in bracket centered and then shim down, if he needs too
Wouldn't that get him closer to pinion angle??

 

I'll post up when I get home and find my notes - but no angle was greater than 5 degrees AFAIR.

Again - each setup is different. My Dakars may not have the same pinion angle as an AAL - my pinion was already pointing up ~ 5 degs, so dropping the CB brought the angles in line.

No vibes whatsoever with a 3/4 spacer.

 

Yes. This isn't rocket science. It's barely even trigonometry.

 

The comment by 303tacoma is news to me (thanks 303). Did you flip your carrier bearing bracket TaterHarry?

 

Both these post in this thread are very helpful

 

Mine wasn't flipped just dropped.

Again - Each and Every Truck Is Different. It's apples and oranges unless you have two identical trucks with exactly the same tires, load in the back, suspension setup etc.

In fact I bet if you took two brand new trucks off the lot you'd probably find some variance in the angles just from manufacturing tolerances.

 

Missed your post until now. Good. Post back your future findings. Gotta get the phasing issue solved too.

Agree 1000% gotta measure, only way to be sure. It's true each install is different.

 

Also when chasing vibe gremlins - get a road-force balance of your tires first, and check your front diff needle bearing for wear.