Help with Pinion Angle

I took some measurements along my driveline to try and diagnose the deceleration vibration. Can anyone take a look and tell me what I need to do to bring them into spec? 2018 TRD OR 3/1” level lift kit

 

I'm confused by all the numbers, here's a vid that explains it all.
https://www.youtube.com/embed/41CGhZvm-Qc

 

https://spicerparts.com/calculators/driveshaft-safe-operating-rpm-calculator

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

https://spicerparts.com/calculators/torsional-analysis-calculator

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

 

You're closer to the alternate method of setting up a 2 piece drive shaft.
Basically, you want the middle w.a. at 0 and the others equal.
A bearing drop will get your middle w.a. to 0. You'll have to figure out how much.
Doing this will increase the first w.a. and lessen the third w.a.
So say, after the bearing drop your first w.a. goes to 3.8 and the third w.a. goes to 0.9, you'd need a 3 degree pinion shim.

 

You likely need the Famous ECGS bushing to replace the driver CV Needle bearing. Try not to use the CB spacer as that is a LAST resort.
Your front shaft should be straight and bolted to the factory mount with NO spacer.

This diagram may help with shims though.
Zero your angle finder on the back flat part of your TCase then take measurements.

I had to do both shins and ECGS on my rig. After leafs start to sag you may need to decrease or take shims out as a new vibe may occur from too much shim angle (very rare)


y-x is working angle one
y-z is working angle two

Difference of those should be less than 1 degree

 

So based on my numbers shown I need a 3 degree shim?

 

The vibration does not go away in 4wd so that rules out the needle bearing. I’m not really following your diagram. I’ve already tried a cb drop and it did nothing to reduce the vibration.

 

No, not necessarily. That's what I estimated after a bearing drop to zero your middle w.a.
2 equal working angles cancel each other. What cancels the third working angle. Nothing; that's why it needs to be 0.

 

Zero your angle finder on the flat part of the TCase where there is that hole on the bottom.

Measure x,y,z

Z is the flat part of your diff facing the front of the truck

y-x you get working angle 1
y-z is working angle 2

The difference of those angles should be 1 degree or less.

Let’s say the difference is 3.5 degrees.
3 degree shims will put you at 0.5 degree working angle which is great

 

Based on the numbers I measured already shown in the picture I posted the difference between those angles is 0.9 degrees.

 

If it is during deceleration I would hesitate to guess it is not the drive shaft which usually shows up under load of acceleration. Have you double checked alignment, wheel balance all which will load more under braking?

 

When I had worn tie rods it was magnified with lift and larger wheels the play was more aggressive on braking when the weight shigpftbtransferred forward more vibration. Just some additional thoughts.

 

Yes the dealership checked everything and said the driveline angles are out because of the lift. The truck only has 5k miles on it so no parts are worn. Just driving me insane trying to figure out what to do

 

I’m so ready to just put the truck back to stock and be done with it

 

Only if you zeroed your scale on your TCase

 

Lol been there

 

You could always get a custom driveshaft made by a nearby shop.

 

Where do you feel the vibes?
Is this deceleration during braking or coasting?
If under braking, can the amount of vibration be controlled by how soft/hard you brake?
1" rear lift block?
Tell me about your wheel/tire setup.
Do you have an alignment sheet?

 

I feel the vibration in the steering wheel mostly but it’s so faint the wheel doesn’t shake. It seems the harder I brake the more it vibrates however it only starts at exactly 25mph and stops by 20. It doesn’t vibrate at any other speed during braking. I’ve tried switching to neutral and 4wd hi and it still does it. I do have a flat 1” rear block. Wheels are 17x9 -12 offset method 312s with 285/70/17 Nitto terra grappler tires. I do not have a copy of the alignment

 

Okay...
What I think might be happening is your wheels/tires are going toe out during braking.
Do you have any unusual wear on the inside of your front tires?
An alignment sheet would really help.
If you have a dealership nearby with an express check, they'll measure it for you for free...at least mine does.