Driveshaft Angle Help?

Hey guys,

Hope everyone is well. Recently installed an Icon RXT leaf pack at option 2, so 2.25”. Then installed a 3 degree toytec aluminum shim along with it, so probably 2.25” plus shim thickness, so probably a total of 2.5”. Made the mistake of not measuring angles the first time, toytec said 3 degree shims were good for 2-3 inches of lift so I went with that. The Front is at about 3 inches (OME nitrocharger with 0.5 inch top spacer). I think I’m getting a vibe mostly noticeable at highway speeds, 50 or 55+. Also, I’m getting a noticeable shudder taking off from a stop at about 5-10 mph. Feeling some decel vibes as well from what I can tell, mostly slowing down at lower speeds to a stop. Doesn’t feel like warped rotors or drums because I didn’t have that issue beforehand.

I got a little angle cube, and went under the truck and measured some angles:

Transfer Case yoke machined surface: 2.5 degrees

Front Driveshaft Slope: 6.2 degrees

Rear Driveshaft Slope: 8.3 degrees

Pinion yoke machined surface: 6.2 degrees


Calculating angles I get:

1st working angle: 3.7 deg (6.2-2.5)

2nd working angle: 2.1 deg (8.3-6.2)

3rd working angle: 2.1 deg (8.3-6.2)


2nd and 3rd angles are equal, which should be the case so I’m hearing…

watching the Toyota technical video the guy says that first two angles sloping down need to add to the pinion angle sloping up, so:

5.8 down and 2.1 up?

This doesn’t make sense because without the 3 degree shim wouldn’t I be at 5.8 and 5.1, so still out of spec technically, correct?


I do not currently have a carrier bearing drop installed, though I have the kit. I took it off before I measured angles. Should I put it back on and re measure? Some were saying not to use them because then the first working angle gets put closer to 5. Maybe not too much of an issue, I don’t know.


I’ve read pretty much every forum post there is to see and I’ve heard a couple different things regarding which angles need to cancel with what, regarding a two piece, 3 joint shaft that our 3rd gen’s have.

Any insight?

thanks!

 

Operating angles should be less than three degrees and cancelation angles less than one degree.
Without seeing your math I think your calculations are the cancelation angles.

 

See if this helps you.

 

Hmm. Let me add that, I’ll show how I arrived at that

 

Thanks, let me take a look!

 

Hmm, 3 degrees should have done it for you unless you put it on backwards, but your measurements appear to be good. Without a CB drop, your front angles are still stock, so you shouldn't have to worry about those. The rear 2 are the ones that need to be close.

 

Yeah, it seemed like on paper it should be good. Skinny part should be facing toward the front and thick part toward the back. I wonder if the pinion’s tilting up enough to cause an angle discrepancy?

 

I'm surprised at a few things here. 3.7 degrees on the first half of the driveshaft seems steep since it's supposed to be considered an extension of the transfer case. Maybe I'm misremembering, but I thought mine was only like 1.5 degrees. the way I understand it, it should be just enough angle to keep the ujoint moving so that it doesn't create weird vibes by being unloaded (working perfectly straight).

It sounds though like your angles are as they should be...although typically I believe the pinion angle is actually supposed to be a bit lower than the center joint angle, due to axle wrap.

The video you watched about angles and adding the first two together, I'm pretty sure is incorrect. I believe the first half is supposed to be an extension of the transfer case and then you treat the rear half like a normal 2-joint driveshaft.

If you removed the shims, then you'd be at 6.2 at the center and back to 3.2 stock, so that might actually work when torque pulls the pinion up. Hard to say without experimenting though.

My first step would probably be to try without the shims. Unless you did that briefly before installing them and had problems then also?

 

I’ve heard so many things, a lot of people were saying that working angle is set from the factory at 0.5-1 degrees, which obvious put isn’t the case here. I’ve heard people having their pinion angle 0.5 degrees less because of axle wrap, so I wonder if a 2 or 3 degree shim would help with this. I think I more installed the shims as a preventative measure so I didn’t have any vibes.

maybe I can take them off, but I have a hard time believing I wouldn’t have any vibrations doing that, because I wouldn’t think the pinion would rise like 3 degrees under torque, though I could be wrong. I don’t think I had axle wrap issues before the shims, though I can’t recall.

Is the best thing to try just taking them off? And run no shims as of now?

 

Would anyone advise a 2.5 degree shim to bring the pinion angle half a degree lower? Would that compensate for axle wrap?

 

If your rear measurements are accurate, your angles look good right now. Axle wrap goes both ways -- if you fix it for acceleration, you may get vibes when slowing down to a stop. These trucks aren't drag racers. I personally would explore other possible issues, but the only ones I can think of are a carrier bearing that has tired rubber, or a bad u-joint.

 

I didn't think about the carrier bearing. On a 2018, it could be sagging and could be why there is 3.7 degrees at the first half. Like I said, I was pretty sure mine was like 1.5 degrees max.

The lift could be exacerbating problems experienced. So actually I probably would look at that first. I'd be more surprised at a bad u-joint, but also possible. My carrier bearing went bad at about 45K, although the rubber was fine. But on a truck multiple years older, totally possible.

 

Take the shims out, torque ubolts and all other leafspring bolts/nuts to 85ft#’s. Drive around and try and replicate vibration. Park on even level surface and take measurements again.

 

The 3 working angles s/b. 1st is 0.5° (no greater than 0.8° and the last 2 s/b equal to ea. other and >< 1-3°

A general rule of thumb for shims is 1°/1" of lift.

 

That’s exactly what I went with originally. I just didn’t measure originally. Had the OEM leaf pack on with a 1.5 inch add a leaf and had no issues whatsoever prior. So that makes me feel like mechanically, I don’t have a ujoint or carrier bearing that’s bad, even if the lift would exacerbate it.

 

I’m really confused as to why people are saying first working angle should be less than one, I didn’t think that first joint even moved except for the small bit of play in the CB. For working angles I’ve heard less than 3 is ideal and definitely shouldn’t be over 5, unless you want your unjoints to wear out quickly.

 

I guess I can probably start by taking the shims out. Maybe I’ll measure too. I’d have a hard time believing angles would equalize under driveshaft torque given the large discrepancy after the lift. Very interesting. I wonder how much of a difference a 2 or 2.5 deg shim would make. I’ll try taking the three’s out before I throw more parts at it, however.

 

When I put the ubolts back on....after I had them all finger tight....I tightened the front 2 more than the back 2 bolts.
The ubolts aren't going to be even with a shim in there. I wanted to be sure I was tightening up the front to insure the yolk was pulling up.

I put chocks in front of the rear tires so the truck wouldn't roll forward any when tightening the ubolts, too.

Have you retorqued the ubolts?
center pins?

Also, after your new leaves settle the shutter might go away. Ride around with some weight in the back and see if anything changes.
Careful not to change to much at once.

 

Thanks for your input. That’s what I did, I at least ran the nuts down at the front of the shim as to pull the axle against the shim and once it contacted evenly on both sides I tightened the bolts evenly. I may start by taking the shims out and seeing what I should do. If I don’t have to, I didn’t want to take everything apart again, but it really isn’t a ton of work to take the shims off. Pretty much just let the axle drip under the jack then pop the pin out.

I’ll see if anyone else chimes in with some good input. Maybe the first thing I will do is take the shims off. Maybe then I’ll get a baseline measurement.

 

Here's what I did:

1. Downloaded a Level app to my phone.
2. Used the level app to measure the angle of the front half of the driveshaft and the back half of the driveshaft. The difference between those 2 is the front angle.
3. Used an L-square against the face of the pinion flange and measured the angle of the pinion. The difference between that and the back half of the driveshaft is the rear angle.
4. Ordered 3 degree shims to get the rear angle closer to the front angle. Angles were near dead-on the same after that, and no more vibrations.

I'm running Deaver Expedition Stage 2, and according to Accutune they give about 2" of lift. I was sagging a bit due to weight, and so my before and after measurements were more than 2", but maybe 2" is for a stock, empty truck.

If you truly raised 3 inches, you may need MORE than a 3 degree shim to get the angles to match. If the angles are the same or under 1 degree difference, I find it doubtful that the vibration you are feeling is due to the driveshaft angles. Either way, you want the angles the same or close to protect your u-joints from premature wear, whether you feel a vibration or not.