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Discussion Starter #1
I recently added new Deaver leaf springs to give me 1.5" of lift and now I have a grinding that feels like I'm driving over rumble strips at 22-32 MPH. It does this in neutral and drive. It gets worse when I accelerate in this MPH range. It has been doing this for over a month now and is progressively getting worse. At one point, my truck bed was loaded with at least a couple hundred pounds of gear and I drove it over 150 miles and I never experienced the grinding. I've shot more grease into the driveshaft and that will quiet it for a little bit. I've noticed that the grease from the driveshaft has been thrown around where the two pieces meet. This is new with the install of the rear lift. I suspect that the grinding is coming from the driveline since it now is being stressed from the rear lift. Thoughts?
 

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Did you happen to drop the carrier bearing when you did the lift? With the rear diff sitting lower now the drive shaft is at an angle and you need to drop it at the carrier bearing to re-align it. When you had weight it dropped the rear end to align it, which is why you didn’t experience it then.
 

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Discussion Starter #3
Did you happen to drop the carrier bearing when you did the lift? With the rear diff sitting lower now the drive shaft is at an angle and you need to drop it at the carrier bearing to re-align it. When you had weight it dropped the rear end to align it, which is why you didn’t experience it then.
No, I didn't drop the carrier bearing. Great advice! I have found a kit from 4wheelparts here: https://www.4wheelparts.com/p/tuff-country-carrier-bearing-drop-kit/24754

I'll be ordering it when I get home.
 

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2015 Toyota Tundra DC SR5 5.7L
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Inserting a drop spacer on the carrier bearing assembly isn't going to properly re-align the drive shaft subsequent to a simple 1.5" rear lift via new leaf pack(s). Given your symptoms (grease spatters from the u-joints) and observations (re-greasing causing the vibration to diminish), the vibration seems to be coming from a failed/failing u-joint in the drive shaft itself. I urge you to verify that before dropping $$$ on parts that might solve your issue.
 

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Discussion Starter #5
I will double check the U-joint to see if it is showing any wear or play.

I expect the carrier bearing drop kit to have a positive affect on the grinding because when the truck bed is loaded with a couple hundred pounds of stuff, the grinding disappears. I believe that when the bed is loaded and sitting lower, the second part of the driveshaft where the grease zerk is located, is pushed back in towards normal operating range. Where as when the truck bed is empty and now lifted, it pulls the two piece driveshaft away from itself causing stress. I believe dropping the carrier bearing will realign the driveshaft, but I'm also curious if it will place that stress elsewhere in front of the carrier bearing.
 

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Discussion Starter #6
Update: I received the carrier bearing drop kit from 4Wheel Parts. The new bolts included in the kit are bigger than factory and the threads don't match. I called 4Wheel Parts and they gave me a refund and let me keep the kit. My next step is to get to Fastenal to find a bolt that will fit.
 

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Discussion Starter #7
Solved! The carrier bearing drop cured my grinding! I used the spacers from 4wheelparts, measured the bolts holding the carrier bearing and bought longer ones. It was an easy install.

Tip: Take out one bolt, unscrew the other side partially, replace the bolt already removed and add the spacer. This way you're not trying to wrestle the driveshaft back in line.
 
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