Drive Shaft Vibrations Solved Step-by-Step

I took the carrier bearing drop spacers off. I think they’re more for 2-4 inch lifts. If anyone wants them I’ll be glad to mail them to you if you’ll pay the shipping. I have $25 in them.

Don’t remember who said it but smaller square shims is all I needed and it seemed to make it much smoother.

 

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Just installed my LT rear. Guess I know what I'm doing next weekend

 

Thanks Scot ! Great post!
I will get the wixey gauge, shims and washers soon! but first I want to be sure if (having no lift kits installed) should I fix leaf springs or replace shock absorber first? check pics and video and let me know....by the way I bought the act 2 months ago!
Thanks


https://www.youtube.com/watch?v=In7-l7FvR7I

 

I haven't lifted my truck yet, but is it worth measuring my current angles on there before I lift?

Would the stock angles benefit anyone?

 

Yes, measure angles before. Also measure your before lift heights.

If you have no vibes now and can get the same angles back after lift you should be vibe free post lift.

 

So I finished up the install of the new IEDS bearing and U-joints last night. Assembly went together well and I used the mounting design @MonkeyProof came up with in an attempt to create the proper drive line angles.

It was an attempt though, I now have a vibration at 15-20 mph and 35 +\- a few mph that fades away and a slight hum at anything over. The way I understand it, I need to add spacing for the carrier bearing to get better angles.

I measured the driveline the best I could using the technique @TscotR214 wrote up in this thread and found my angle to be 1.9 degrees at the flange for the transfer case and 8.3 degrees at the differential. So a difference of 6.4 degrees. I believe these are supposed to be < 3 degrees but wanted to confirm?

When I started this project, I had 2.2 degrees at the transfer case flange and 7.7 degrees at the diff. I found this interesting due to starting the spacer at 1 3/8” as @MonkeyProof did expecting this to be a decent starting point. I added a 1/8” washer after in an attempt to fix the vibration but ran out of threads for the bolt.

 

Looks like you measured wrong the angles. Need more info to calculate.

 

Was that directed towards me?

 

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Yes. Your values are off the chart which means you measured wrong or you jumped the truck in the Grand Canyon. You missed to measure the middle U-join angles and calculate.

 

I fail to see where I’m supposed to measure at the U-joint in the OP. I’ll retake measurements with the new shims and post them up. What am I calculating exactly?

 

This is awesome information. Thanks O P and all how added to it!

 

I was talking with a tech with Spc alignment, he said with a carrier bearing ( i have a double cab long bed), your angle in back of the carrier bearing should be equal but opposite of the angle of the differential. He said no need to measure from transfer case to carrier bearing.

 

Then how you going to find the working angle of the U-joint at CB?

 

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I asked him, he said that’s not needed, because the angle from the transfer case to the carrier bearing does not ever change it’s fixed, And you need to cancel out the angles that you created by lifting or lowering

 

The tech SPC also said a good rule of thumb is 1° Of shim for every inch of lift. My long bed seems like it’s lower in the rear by about an inch than the short beds at the dealership, and the Leaf springs are flat or almost in a negative arch already with 112 Miles

 

OK so after reading throw this thread and meny like it over and over and over again is it safe to conclude that the take off shutter is coming from the carrier bearing angel not being right ? I don't have any vibration. Just the take off shutter at 5 hmp. It is smooth as glass the rest of the time. I only have a 1in lift in the rear plus an half inch do to the thickness of my 8 leave spring. I just want to correct the take off shutter. I did do a 1/4in spacer on the carrier bearing and didn't really do much. Let me add that taking the lift out made the take off shutter alot better but still there ever so slite at times. Any advice on correcting that ?

 

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So I installed an OME 3" lift and LR UCAs. I also have a CB drop kit installed. Post lift I have a constant small vibration. I only feel it through the pedal and no where else. Here's my driveline angles. I assume the angles are relative to 90 degrees so I listed what my angle finder said and the difference between that and 90 degrees.




Should I shim the rear axle or doing anything at all with shimming? Or is my vibration coming from something else and all these numbers look fine? Thank you.